diff --git a/package-lock.json b/package-lock.json
index 8ceb8ac694..9a28161a8d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -121,7 +121,7 @@
         "react-window": "1.8.6",
         "react-youtube": "7.13.1",
         "redux": "4.0.4",
-        "redux-thunk": "2.2.0",
+        "redux-thunk": "2.4.1",
         "resemblejs": "4.0.0",
         "seamless-scroll-polyfill": "2.1.8",
         "styled-components": "3.4.9",
@@ -16941,9 +16941,12 @@
       }
     },
     "node_modules/redux-thunk": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/redux-thunk/-/redux-thunk-2.2.0.tgz",
-      "integrity": "sha1-5hWhbha0ehmlFXZhM9Hj6Zt4UuU="
+      "version": "2.4.1",
+      "resolved": "https://registry.npmjs.org/redux-thunk/-/redux-thunk-2.4.1.tgz",
+      "integrity": "sha512-OOYGNY5Jy2TWvTL1KgAlVy6dcx3siPJ1wTq741EPyUKfn6W6nChdICjZwCd0p8AZBs5kWpZlbkXW2nE/zjUa+Q==",
+      "peerDependencies": {
+        "redux": "^4"
+      }
     },
     "node_modules/regenerate": {
       "version": "1.4.2",
@@ -33153,9 +33156,9 @@
       }
     },
     "redux-thunk": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/redux-thunk/-/redux-thunk-2.2.0.tgz",
-      "integrity": "sha1-5hWhbha0ehmlFXZhM9Hj6Zt4UuU="
+      "version": "2.4.1",
+      "resolved": "https://registry.npmjs.org/redux-thunk/-/redux-thunk-2.4.1.tgz",
+      "integrity": "sha512-OOYGNY5Jy2TWvTL1KgAlVy6dcx3siPJ1wTq741EPyUKfn6W6nChdICjZwCd0p8AZBs5kWpZlbkXW2nE/zjUa+Q=="
     },
     "regenerate": {
       "version": "1.4.2",
diff --git a/package.json b/package.json
index a1f51fed63..6ce5c0fcea 100644
--- a/package.json
+++ b/package.json
@@ -126,7 +126,7 @@
     "react-window": "1.8.6",
     "react-youtube": "7.13.1",
     "redux": "4.0.4",
-    "redux-thunk": "2.2.0",
+    "redux-thunk": "2.4.1",
     "resemblejs": "4.0.0",
     "seamless-scroll-polyfill": "2.1.8",
     "styled-components": "3.4.9",
diff --git a/react/features/app/types.ts b/react/features/app/types.ts
index a63baac3e1..e518c6748a 100644
--- a/react/features/app/types.ts
+++ b/react/features/app/types.ts
@@ -1,4 +1,5 @@
-import { AnyAction, Dispatch } from 'redux';
+import { AnyAction } from 'redux';
+import { ThunkDispatch } from 'redux-thunk';
 
 import { IAnalyticsState } from '../analytics/reducer';
 import { IAuthenticationState } from '../authentication/reducer';
@@ -75,7 +76,7 @@ import { IVideoSipGW } from '../videosipgw/reducer';
 import { IVirtualBackground } from '../virtual-background/reducer';
 
 export interface IStore {
-    dispatch: Dispatch<AnyAction>;
+    dispatch: ThunkDispatch<IState, void, AnyAction>;
     getState: () => IState;
 }
 
diff --git a/react/features/authentication/components/web/LoginDialog.tsx b/react/features/authentication/components/web/LoginDialog.tsx
index cef839c6a0..e0d9b8c28e 100644
--- a/react/features/authentication/components/web/LoginDialog.tsx
+++ b/react/features/authentication/components/web/LoginDialog.tsx
@@ -145,7 +145,10 @@ class LoginDialog extends Component<Props, State> {
             dispatch
         } = this.props;
         const { password, username } = this.state;
-        const jid = toJid(username, configHosts);
+        const jid = toJid(username, configHosts ?? {
+            authdomain: '',
+            domain: ''
+        });
 
         if (conference) {
             dispatch(authenticateAndUpgradeRole(jid, password, conference));
@@ -217,7 +220,8 @@ class LoginDialog extends Component<Props, State> {
                 const { credentials } = error;
 
                 if (credentials
-                    && credentials.jid === toJid(username, configHosts)
+                    && credentials.jid === toJid(username, configHosts ?? { authdomain: '',
+                        domain: '' })
                     && credentials.password === password) {
                     messageKey = t('dialog.incorrectPassword');
                 }
diff --git a/react/features/base/conference/reducer.ts b/react/features/base/conference/reducer.ts
index c955c0af4d..42d71308f0 100644
--- a/react/features/base/conference/reducer.ts
+++ b/react/features/base/conference/reducer.ts
@@ -60,7 +60,7 @@ export interface IConferenceState {
     password?: string;
     passwordRequired?: Object;
     pendingSubjectChange?: string;
-    room?: Object;
+    room?: string;
     startAudioMutedPolicy?: boolean;
     startReactionsMuted?: boolean;
     startVideoMutedPolicy?: boolean;
diff --git a/react/features/base/config/actions.js b/react/features/base/config/actions.ts
similarity index 92%
rename from react/features/base/config/actions.js
rename to react/features/base/config/actions.ts
index 67be4a3114..5b7957b97e 100644
--- a/react/features/base/config/actions.js
+++ b/react/features/base/config/actions.ts
@@ -1,10 +1,9 @@
-// @flow
-
+// @ts-ignore
 import { jitsiLocalStorage } from '@jitsi/js-utils';
-import type { Dispatch } from 'redux';
+import { Dispatch } from 'redux';
 
-import { addKnownDomains } from '../known-domains';
-import { parseURIString } from '../util';
+import { addKnownDomains } from '../known-domains/actions';
+import { parseURIString } from '../util/uri';
 
 import {
     CONFIG_WILL_LOAD,
@@ -13,8 +12,9 @@ import {
     UPDATE_CONFIG,
     OVERWRITE_CONFIG
 } from './actionTypes';
+import { IConfig } from './configType';
 import { _CONFIG_STORE_PREFIX } from './constants';
-import { setConfigFromURLParams } from './functions';
+import { setConfigFromURLParams } from './functions.any';
 
 
 /**
@@ -23,7 +23,7 @@ import { setConfigFromURLParams } from './functions';
  * @param {Object} config - The new options (to add).
  * @returns {Function}
  */
-export function updateConfig(config: Object) {
+export function updateConfig(config: IConfig) {
     return {
         type: UPDATE_CONFIG,
         config
@@ -116,6 +116,8 @@ export function setConfig(config: Object = {}) {
                 // On Web the config also comes from the window.config global,
                 // but it is resolved in the loadConfig procedure.
                 config,
+
+                // @ts-ignore
                 window.interfaceConfig,
                 locationURL);
 
@@ -142,6 +144,7 @@ export function storeConfig(baseURL: string, config: Object) {
         let b = false;
 
         try {
+            // @ts-ignore
             if (typeof window.config === 'undefined' || window.config !== config) {
                 jitsiLocalStorage.setItem(`${_CONFIG_STORE_PREFIX}/${baseURL}`, JSON.stringify(config));
                 b = true;
@@ -153,7 +156,7 @@ export function storeConfig(baseURL: string, config: Object) {
         // If base/config knows a domain, then the app knows it.
         if (b) {
             try {
-                dispatch(addKnownDomains(parseURIString(baseURL).host));
+                dispatch(addKnownDomains(parseURIString(baseURL)?.host));
             } catch (e) {
                 // Ignore the error because the fiddling with "known domains" is
                 // a side effect here.
diff --git a/react/features/base/config/configType.ts b/react/features/base/config/configType.ts
index bfe56a3c43..43e1d585ad 100644
--- a/react/features/base/config/configType.ts
+++ b/react/features/base/config/configType.ts
@@ -105,6 +105,7 @@ export interface IConfig {
         scriptURLs?: Array<string>;
     };
     apiLogLevels?: Array<'warn' | 'log' | 'error' | 'info' | 'debug'>;
+    appId?: string;
     audioLevelsInterval?: number;
     audioQuality?: {
         opusMaxAverageBitrate?: number | null;
@@ -316,6 +317,8 @@ export interface IConfig {
         disabled?: boolean;
     };
     gravatarBaseURL?: string;
+    guestDialOutStatusUrl?: string;
+    guestDialOutUrl?: string;
     helpCentreURL?: string;
     hiddenPremeetingButtons?: Array<'microphone' | 'camera' | 'select-background' | 'invite' | 'settings'>;
     hideAddRoomButton?: boolean;
@@ -354,7 +357,7 @@ export interface IConfig {
         notifyAllParticipants?: boolean;
     };
     localSubject?: string;
-    locationURL?: string;
+    locationURL?: URL;
     maxFullResolutionParticipants?: number;
     moderatedRoomServiceUrl?: string;
     mouseMoveCallbackInterval?: number;
@@ -403,12 +406,14 @@ export interface IConfig {
         hideStorageWarning?: boolean;
         sharingEnabled?: boolean;
     };
+    recordingSharingUrl?: string;
     remoteVideoMenu?: {
         disableGrantModerator?: boolean;
         disableKick?: boolean;
         disablePrivateChat?: boolean;
         disabled?: boolean;
     };
+    replaceParticipant?: string;
     requireDisplayName?: boolean;
     resolution?: number;
     roomPasswordNumberOfDigits?: number;
@@ -417,6 +422,7 @@ export interface IConfig {
         enabled?: boolean;
         mode?: 'always' | 'recording';
     };
+    serviceUrl?: string;
     speakerStatsOrder?: Array<'role' | 'name' | 'hasLeft'>;
     startAudioMuted?: boolean;
     startAudioOnly?: boolean;
@@ -481,4 +487,5 @@ export interface IConfig {
     webrtcIceTcpDisable?: boolean;
     webrtcIceUdpDisable?: boolean;
     websocket?: string;
+    websocketKeepAliveUrl?: string;
 }
diff --git a/react/features/base/config/configWhitelist.js b/react/features/base/config/configWhitelist.ts
similarity index 100%
rename from react/features/base/config/configWhitelist.js
rename to react/features/base/config/configWhitelist.ts
diff --git a/react/features/base/config/constants.js b/react/features/base/config/constants.ts
similarity index 100%
rename from react/features/base/config/constants.js
rename to react/features/base/config/constants.ts
diff --git a/react/features/base/config/extraConfigWhitelist.js b/react/features/base/config/extraConfigWhitelist.ts
similarity index 100%
rename from react/features/base/config/extraConfigWhitelist.js
rename to react/features/base/config/extraConfigWhitelist.ts
diff --git a/react/features/base/config/functions.any.js b/react/features/base/config/functions.any.ts
similarity index 85%
rename from react/features/base/config/functions.any.js
rename to react/features/base/config/functions.any.ts
index 8173ae84f0..aa011bc3e2 100644
--- a/react/features/base/config/functions.any.js
+++ b/react/features/base/config/functions.any.ts
@@ -1,12 +1,15 @@
-// @flow
-
+/* eslint-disable lines-around-comment */
+// @ts-ignore
 import Bourne from '@hapi/bourne';
+// @ts-ignore
 import { jitsiLocalStorage } from '@jitsi/js-utils';
 import _ from 'lodash';
 
+import { IState } from '../../app/types';
 import { browser } from '../lib-jitsi-meet';
-import { parseURLParams } from '../util';
+import { parseURLParams } from '../util/parseURLParams';
 
+import { IConfig } from './configType';
 import CONFIG_WHITELIST from './configWhitelist';
 import { _CONFIG_STORE_PREFIX, FEATURE_FLAGS } from './constants';
 import INTERFACE_CONFIG_WHITELIST from './interfaceConfigWhitelist';
@@ -46,7 +49,7 @@ export function createFakeConfig(baseURL: string) {
  * @param {Object} state - The global state.
  * @returns {string}
  */
-export function getMeetingRegion(state: Object) {
+export function getMeetingRegion(state: IState) {
     return state['features/base/config']?.deploymentInfo?.region || '';
 }
 
@@ -56,7 +59,7 @@ export function getMeetingRegion(state: Object) {
  * @param {Object} state - The global state.
  * @returns {boolean}
  */
-export function getMultipleVideoSupportFeatureFlag(state: Object) {
+export function getMultipleVideoSupportFeatureFlag(state: IState) {
     return getFeatureFlag(state, FEATURE_FLAGS.MULTIPLE_VIDEO_STREAMS_SUPPORT)
         && getSourceNameSignalingFeatureFlag(state);
 }
@@ -67,7 +70,7 @@ export function getMultipleVideoSupportFeatureFlag(state: Object) {
  * @param {Object} state - The global state.
  * @returns {boolean}
  */
-export function getMultipleVideoSendingSupportFeatureFlag(state: Object) {
+export function getMultipleVideoSendingSupportFeatureFlag(state: IState) {
     return navigator.product !== 'ReactNative'
         && getMultipleVideoSupportFeatureFlag(state) && isUnifiedPlanEnabled(state);
 }
@@ -78,7 +81,7 @@ export function getMultipleVideoSendingSupportFeatureFlag(state: Object) {
  * @param {Object} state - The global state.
  * @returns {boolean}
  */
-export function getSourceNameSignalingFeatureFlag(state: Object) {
+export function getSourceNameSignalingFeatureFlag(state: IState) {
     return getFeatureFlag(state, FEATURE_FLAGS.SOURCE_NAME_SIGNALING);
 }
 
@@ -89,10 +92,10 @@ export function getSourceNameSignalingFeatureFlag(state: Object) {
  * @param {string} featureFlag - The name of the feature flag.
  * @returns {boolean}
  */
-export function getFeatureFlag(state: Object, featureFlag: string) {
+export function getFeatureFlag(state: IState, featureFlag: string) {
     const featureFlags = state['features/base/config']?.flags || {};
 
-    return Boolean(featureFlags[featureFlag]);
+    return Boolean(featureFlags[featureFlag as keyof typeof featureFlags]);
 }
 
 /**
@@ -101,7 +104,7 @@ export function getFeatureFlag(state: Object, featureFlag: string) {
  * @param {Object} state - The global state.
  * @returns {boolean}
  */
-export function getDisableRemoveRaisedHandOnFocus(state: Object) {
+export function getDisableRemoveRaisedHandOnFocus(state: IState) {
     return state['features/base/config']?.disableRemoveRaisedHandOnFocus || false;
 }
 
@@ -111,7 +114,7 @@ export function getDisableRemoveRaisedHandOnFocus(state: Object) {
  * @param {Object} state - The global state.
  * @returns {string}
  */
-export function getRecordingSharingUrl(state: Object) {
+export function getRecordingSharingUrl(state: IState) {
     return state['features/base/config'].recordingSharingUrl;
 }
 
@@ -136,7 +139,7 @@ export function getRecordingSharingUrl(state: Object) {
  * }.
  * @returns {void}
  */
-export function overrideConfigJSON(config: ?Object, interfaceConfig: ?Object, json: Object) {
+export function overrideConfigJSON(config: IConfig, interfaceConfig: any, json: any) {
     for (const configName of Object.keys(json)) {
         let configObj;
 
@@ -147,7 +150,7 @@ export function overrideConfigJSON(config: ?Object, interfaceConfig: ?Object, js
         }
         if (configObj) {
             const configJSON
-                = getWhitelistedJSON(configName, json[configName]);
+                = getWhitelistedJSON(configName as 'interfaceConfig' | 'config', json[configName]);
 
             if (!_.isEmpty(configJSON)) {
                 logger.info(
@@ -177,7 +180,7 @@ export function overrideConfigJSON(config: ?Object, interfaceConfig: ?Object, js
  * @returns {Object} - The result object only with the keys
  * that are whitelisted.
  */
-export function getWhitelistedJSON(configName: string, configJSON: Object): Object {
+export function getWhitelistedJSON(configName: 'interfaceConfig' | 'config', configJSON: any): Object {
     if (configName === 'interfaceConfig') {
         return _.pick(configJSON, INTERFACE_CONFIG_WHITELIST);
     } else if (configName === 'config') {
@@ -193,9 +196,9 @@ export function getWhitelistedJSON(configName: string, configJSON: Object): Obje
  * @param {Object} state - The state of the app.
  * @returns {boolean}
  */
-export function isNameReadOnly(state: Object): boolean {
-    return state['features/base/config'].disableProfile
-        || state['features/base/config'].readOnlyName;
+export function isNameReadOnly(state: IState): boolean {
+    return Boolean(state['features/base/config'].disableProfile
+        || state['features/base/config'].readOnlyName);
 }
 
 /**
@@ -204,7 +207,7 @@ export function isNameReadOnly(state: Object): boolean {
  * @param {Object} state - The state of the app.
  * @returns {boolean}
  */
-export function isDisplayNameVisible(state: Object): boolean {
+export function isDisplayNameVisible(state: IState): boolean {
     return !state['features/base/config'].hideDisplayName;
 }
 
@@ -214,7 +217,7 @@ export function isDisplayNameVisible(state: Object): boolean {
  * @param {Object} state - The state of the app.
  * @returns {boolean}
  */
-export function isUnifiedPlanEnabled(state: Object): boolean {
+export function isUnifiedPlanEnabled(state: IState): boolean {
     const { enableUnifiedOnChrome = true } = state['features/base/config'];
 
     return browser.supportsUnifiedPlan()
@@ -232,7 +235,7 @@ export function isUnifiedPlanEnabled(state: Object): boolean {
  * from {@code baseURL} and stored with {@code storeConfig} if it was restored;
  * otherwise, {@code undefined}.
  */
-export function restoreConfig(baseURL: string): ?Object {
+export function restoreConfig(baseURL: string) {
     const key = `${_CONFIG_STORE_PREFIX}/${baseURL}`;
     const config = jitsiLocalStorage.getItem(key);
 
@@ -266,9 +269,9 @@ export function restoreConfig(baseURL: string): ?Object {
  * @returns {void}
  */
 export function setConfigFromURLParams(
-        config: ?Object, interfaceConfig: ?Object, location: Object) {
+        config: IConfig, interfaceConfig: any, location: string | URL) {
     const params = parseURLParams(location);
-    const json = {};
+    const json: any = {};
 
     // At this point we have:
     // params = {
@@ -292,7 +295,7 @@ export function setConfigFromURLParams(
     for (const param of Object.keys(params)) {
         let base = json;
         const names = param.split('.');
-        const last = names.pop();
+        const last = names.pop() ?? '';
 
         for (const name of names) {
             base = base[name] = base[name] || {};
diff --git a/react/features/base/config/functions.native.js b/react/features/base/config/functions.native.ts
similarity index 70%
rename from react/features/base/config/functions.native.js
rename to react/features/base/config/functions.native.ts
index c4d477c3b7..82692d9b83 100644
--- a/react/features/base/config/functions.native.js
+++ b/react/features/base/config/functions.native.ts
@@ -1,8 +1,10 @@
-// @flow
-
 import { NativeModules } from 'react-native';
 
-import { getFeatureFlag, REPLACE_PARTICIPANT } from '../flags';
+import { IState } from '../../app/types';
+import { REPLACE_PARTICIPANT } from '../flags/constants';
+import { getFeatureFlag } from '../flags/functions';
+
+import { IConfig } from './configType';
 
 export * from './functions.any';
 
@@ -12,7 +14,8 @@ export * from './functions.any';
  * @param {*} config - The configuration which needs to be cleaned up.
  * @returns {void}
  */
-export function _cleanupConfig(config: Object) {
+export function _cleanupConfig(config: IConfig) {
+    config.analytics ??= {};
     config.analytics.scriptURLs = [];
     if (NativeModules.AppInfo.LIBRE_BUILD) {
         delete config.analytics?.amplitudeAPPKey;
@@ -29,6 +32,6 @@ export function _cleanupConfig(config: Object) {
  * @param {Object} state - The state of the app.
  * @returns {boolean}
  */
-export function getReplaceParticipant(state: Object): string {
+export function getReplaceParticipant(state: IState): string {
     return getFeatureFlag(state, REPLACE_PARTICIPANT, false);
 }
diff --git a/react/features/base/config/functions.web.js b/react/features/base/config/functions.web.ts
similarity index 77%
rename from react/features/base/config/functions.web.js
rename to react/features/base/config/functions.web.ts
index 07d7ba1032..3d19866ac6 100644
--- a/react/features/base/config/functions.web.js
+++ b/react/features/base/config/functions.web.ts
@@ -1,5 +1,6 @@
-// @flow
+import { IState } from '../../app/types';
 
+import { IConfig } from './configType';
 import { TOOLBAR_BUTTONS } from './constants';
 
 export * from './functions.any';
@@ -10,7 +11,7 @@ export * from './functions.any';
  * @param {*} config - The configuration which needs to be cleaned up.
  * @returns {void}
  */
-export function _cleanupConfig(config: Object) { // eslint-disable-line no-unused-vars
+export function _cleanupConfig(config: IConfig) { // eslint-disable-line @typescript-eslint/no-unused-vars
 }
 
 /**
@@ -19,7 +20,7 @@ export function _cleanupConfig(config: Object) { // eslint-disable-line no-unuse
  * @param {Object} state - The state of the app.
  * @returns {string}
  */
-export function getDialOutStatusUrl(state: Object): string {
+export function getDialOutStatusUrl(state: IState): string | undefined {
     return state['features/base/config'].guestDialOutStatusUrl;
 }
 
@@ -29,7 +30,7 @@ export function getDialOutStatusUrl(state: Object): string {
  * @param {Object} state - The state of the app.
  * @returns {string}
  */
-export function getDialOutUrl(state: Object): string {
+export function getDialOutUrl(state: IState): string | undefined {
     return state['features/base/config'].guestDialOutUrl;
 }
 
@@ -39,7 +40,7 @@ export function getDialOutUrl(state: Object): string {
  * @param {Object} state - The state of the app.
  * @returns {boolean}
  */
-export function getReplaceParticipant(state: Object): string {
+export function getReplaceParticipant(state: IState): string | undefined {
     return state['features/base/config'].replaceParticipant;
 }
 
@@ -49,7 +50,7 @@ export function getReplaceParticipant(state: Object): string {
  * @param {Object} state - The redux state.
  * @returns {Array<string>} - The list of enabled toolbar buttons.
  */
-export function getToolbarButtons(state: Object): Array<string> {
+export function getToolbarButtons(state: IState): Array<string> {
     const { toolbarButtons } = state['features/base/config'];
 
     return Array.isArray(toolbarButtons) ? toolbarButtons : TOOLBAR_BUTTONS;
@@ -63,7 +64,7 @@ export function getToolbarButtons(state: Object): Array<string> {
  * @param {Object|Array<string>} state - The redux state or the array with the enabled buttons.
  * @returns {boolean} - True if the button is enabled and false otherwise.
  */
-export function isToolbarButtonEnabled(buttonName: string, state: Object | Array<string>) {
+export function isToolbarButtonEnabled(buttonName: string, state: IState | Array<string>) {
     const buttons = Array.isArray(state) ? state : getToolbarButtons(state);
 
     return buttons.includes(buttonName);
@@ -75,7 +76,7 @@ export function isToolbarButtonEnabled(buttonName: string, state: Object | Array
  * @param {Object} state - The state of the app.
  * @returns {boolean}
  */
-export function areAudioLevelsEnabled(state: Object): boolean {
+export function areAudioLevelsEnabled(state: IState): boolean {
     // Default to false for React Native as audio levels are of no interest to the mobile app.
     return navigator.product !== 'ReactNative' && !state['features/base/config'].disableAudioLevels;
 }
diff --git a/react/features/base/config/getRoomName.js b/react/features/base/config/getRoomName.ts
similarity index 73%
rename from react/features/base/config/getRoomName.js
rename to react/features/base/config/getRoomName.ts
index b787b6f7db..fa0ba05fd4 100644
--- a/react/features/base/config/getRoomName.js
+++ b/react/features/base/config/getRoomName.ts
@@ -1,13 +1,11 @@
-// @flow
-
-import { getBackendSafeRoomName } from '../util';
+import { getBackendSafeRoomName } from '../util/uri';
 
 /**
  * Builds and returns the room name.
  *
  * @returns {string}
  */
-export default function getRoomName(): ?string {
+export default function getRoomName(): string | undefined {
     const path = window.location.pathname;
 
     // The last non-directory component of the path (name) is the room.
diff --git a/react/features/base/config/interfaceConfigWhitelist.js b/react/features/base/config/interfaceConfigWhitelist.ts
similarity index 100%
rename from react/features/base/config/interfaceConfigWhitelist.js
rename to react/features/base/config/interfaceConfigWhitelist.ts
diff --git a/react/features/base/config/logger.js b/react/features/base/config/logger.ts
similarity index 90%
rename from react/features/base/config/logger.js
rename to react/features/base/config/logger.ts
index 86b320c93a..3cc2d0acb9 100644
--- a/react/features/base/config/logger.js
+++ b/react/features/base/config/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../logging/functions';
 
 export default getLogger('features/base/config');
diff --git a/react/features/base/config/middleware.js b/react/features/base/config/middleware.ts
similarity index 87%
rename from react/features/base/config/middleware.js
rename to react/features/base/config/middleware.ts
index ea2aa0c203..82adeb27d4 100644
--- a/react/features/base/config/middleware.js
+++ b/react/features/base/config/middleware.ts
@@ -1,9 +1,13 @@
+import { AnyAction } from 'redux';
+
+import { IStore } from '../../app/types';
 import { getFeatureFlag } from '../flags/functions';
-import { MiddlewareRegistry } from '../redux';
-import { updateSettings } from '../settings';
+import MiddlewareRegistry from '../redux/MiddlewareRegistry';
+import { updateSettings } from '../settings/actions';
 
 import { SET_CONFIG, OVERWRITE_CONFIG } from './actionTypes';
 import { updateConfig } from './actions';
+import { IConfig } from './configType';
 
 /**
  * The middleware of the feature {@code base/config}.
@@ -37,7 +41,7 @@ MiddlewareRegistry.register(store => next => action => {
  * @private
  * @returns {*} The return value of {@code next(action)}.
  */
-function _setConfig({ dispatch, getState }, next, action) {
+function _setConfig({ dispatch, getState }: IStore, next: Function, action: AnyAction) {
     // The reducer is doing some alterations to the config passed in the action,
     // so make sure it's the final state by waiting for the action to be
     // reduced.
@@ -46,7 +50,7 @@ function _setConfig({ dispatch, getState }, next, action) {
 
     // Update the config with user defined settings.
     const settings = state['features/base/settings'];
-    const config = {};
+    const config: IConfig = {};
 
     if (typeof settings.disableP2P !== 'undefined') {
         config.p2p = { enabled: !settings.disableP2P };
@@ -77,7 +81,9 @@ function _setConfig({ dispatch, getState }, next, action) {
     // not be the global variable which is being modified anymore due to
     // different merge methods being used along the way. The global variable
     // must be synchronized with the final state resolved by the reducer.
+    // @ts-ignore
     if (typeof window.config !== 'undefined') {
+        // @ts-ignore
         window.config = state['features/base/config'];
     }
 
@@ -96,7 +102,7 @@ function _setConfig({ dispatch, getState }, next, action) {
  * @private
  * @returns {*} The return value of {@code next(action)}.
  */
-function _updateSettings({ dispatch }, next, action) {
+function _updateSettings({ dispatch }: IStore, next: Function, action: AnyAction) {
     const { config: { doNotFlipLocalVideo } } = action;
 
     if (doNotFlipLocalVideo === true) {
diff --git a/react/features/base/connection/actions.any.js b/react/features/base/connection/actions.any.ts
similarity index 87%
rename from react/features/base/connection/actions.any.js
rename to react/features/base/connection/actions.any.ts
index 4c36ef45af..8b1e66d4ca 100644
--- a/react/features/base/connection/actions.any.js
+++ b/react/features/base/connection/actions.any.ts
@@ -1,10 +1,11 @@
 import _ from 'lodash';
 
+import { IState } from '../../app/types';
 import {
     appendURLParam,
     getBackendSafeRoomName,
     parseURIString
-} from '../util';
+} from '../util/uri';
 
 import logger from './logger';
 
@@ -16,7 +17,7 @@ import logger from './logger';
  * @returns {Object} The options to be passed to the constructor of
  * {@code JitsiConnection}.
  */
-export function constructOptions(state) {
+export function constructOptions(state: IState) {
     // Deep clone the options to make sure we don't modify the object in the
     // redux store.
     const options = _.cloneDeep(state['features/base/config']);
@@ -36,14 +37,14 @@ export function constructOptions(state) {
 
         if (bosh.startsWith('//')) {
             // By default our config.js doesn't include the protocol.
-            bosh = `${locationURL.protocol}${bosh}`;
+            bosh = `${locationURL?.protocol}${bosh}`;
         } else if (bosh.startsWith('/')) {
             // Handle relative URLs, which won't work on mobile.
             const {
                 protocol,
                 host,
                 contextRoot
-            } = parseURIString(locationURL.href);
+            } = parseURIString(locationURL?.href);
 
             bosh = `${protocol}//${host}${contextRoot || '/'}${bosh.substr(1)}`;
         }
@@ -60,10 +61,10 @@ export function constructOptions(state) {
     if (serviceUrl && room) {
         const roomName = getBackendSafeRoomName(room);
 
-        options.serviceUrl = appendURLParam(serviceUrl, 'room', roomName);
+        options.serviceUrl = appendURLParam(serviceUrl, 'room', roomName ?? '');
 
         if (options.websocketKeepAliveUrl) {
-            options.websocketKeepAliveUrl = appendURLParam(options.websocketKeepAliveUrl, 'room', roomName);
+            options.websocketKeepAliveUrl = appendURLParam(options.websocketKeepAliveUrl, 'room', roomName ?? '');
         }
     }
 
diff --git a/react/features/base/connection/actions.native.js b/react/features/base/connection/actions.native.ts
similarity index 95%
rename from react/features/base/connection/actions.native.js
rename to react/features/base/connection/actions.native.ts
index 96bcb278e9..84831b16a2 100644
--- a/react/features/base/connection/actions.native.js
+++ b/react/features/base/connection/actions.native.ts
@@ -1,8 +1,9 @@
-// @flow
-
-import type { Dispatch } from 'redux';
+/* eslint-disable lines-around-comment */
+import { Dispatch } from 'redux';
 
+// @ts-ignore
 import { conferenceLeft, conferenceWillLeave } from '../conference/actions';
+// @ts-ignore
 import { getCurrentConference } from '../conference/functions';
 import JitsiMeetJS, { JitsiConnectionEvents } from '../lib-jitsi-meet';
 
@@ -36,34 +37,34 @@ export type ConnectionFailedError = {
         /**
          * The XMPP user's ID.
          */
-        jid: string,
+        jid: string;
 
         /**
          * The XMPP user's password.
          */
-        password: string
-    },
+        password: string;
+    };
 
     /**
      * The details about the connection failed event.
      */
-    details?: Object,
+    details?: Object;
 
     /**
      * Error message.
      */
-    message?: string,
+    message?: string;
 
     /**
      * One of {@link JitsiConnectionError} constants (defined in
      * lib-jitsi-meet).
      */
-    name: string,
+    name: string;
 
     /**
      * Indicates whether this event is recoverable or not.
      */
-    recoverable?: boolean
+    recoverable?: boolean;
 };
 
 /**
@@ -73,7 +74,7 @@ export type ConnectionFailedError = {
  * @param {string} [password] - The XMPP user's password.
  * @returns {Function}
  */
-export function connect(id: ?string, password: ?string) {
+export function connect(id?: string, password?: string) {
     return (dispatch: Dispatch<any>, getState: Function) => {
         const state = getState();
         const options = constructOptions(state);
@@ -141,7 +142,7 @@ export function connect(id: ?string, password: ?string) {
         function _onConnectionFailed( // eslint-disable-line max-params
                 err: string,
                 msg: string,
-                credentials: Object,
+                credentials: any,
                 details: Object) {
             unsubscribe();
             dispatch(
@@ -253,7 +254,7 @@ export function connectionFailed(
  *     connection: JitsiConnection
  * }}
  */
-function _connectionWillConnect(connection) {
+function _connectionWillConnect(connection: Object) {
     return {
         type: CONNECTION_WILL_CONNECT,
         connection
@@ -286,7 +287,7 @@ export function disconnect() {
 
             promise
                 = conference_.leave()
-                    .catch(error => {
+                    .catch((error: Error) => {
                         logger.warn(
                             'JitsiConference.leave() rejected with:',
                             error);
@@ -328,7 +329,7 @@ export function disconnect() {
  *     locationURL: URL
  * }}
  */
-export function setLocationURL(locationURL: ?URL) {
+export function setLocationURL(locationURL?: URL) {
     return {
         type: SET_LOCATION_URL,
         locationURL
diff --git a/react/features/base/connection/actions.web.js b/react/features/base/connection/actions.web.ts
similarity index 75%
rename from react/features/base/connection/actions.web.js
rename to react/features/base/connection/actions.web.ts
index b11c36fb54..a5b96c7988 100644
--- a/react/features/base/connection/actions.web.js
+++ b/react/features/base/connection/actions.web.ts
@@ -1,12 +1,8 @@
-// @flow
+import { IStore } from '../../app/types';
+import { configureInitialDevices } from '../devices/actions';
+import { getBackendSafeRoomName } from '../util/uri';
 
-import type { Dispatch } from 'redux';
-
-declare var APP: Object;
-declare var config: Object;
-
-import { configureInitialDevices } from '../devices';
-import { getBackendSafeRoomName } from '../util';
+declare const APP: any;
 
 export {
     connectionDisconnected,
@@ -24,7 +20,7 @@ export * from './actions.any';
  * @returns {Promise<JitsiConnection>}
  */
 export function connect() {
-    return (dispatch: Dispatch<any>, getState: Function) => {
+    return (dispatch: IStore['dispatch'], getState: IStore['getState']) => {
         const room = getBackendSafeRoomName(getState()['features/base/conference'].room);
 
         // XXX For web based version we use conference initialization logic
@@ -32,7 +28,7 @@ export function connect() {
         return dispatch(configureInitialDevices()).then(
             () => APP.conference.init({
                 roomName: room
-            }).catch(error => {
+            }).catch((error: Error) => {
                 APP.API.notifyConferenceLeft(APP.conference.roomName);
                 logger.error(error);
             }));
@@ -46,7 +42,7 @@ export function connect() {
  * request for call feedback.
  * @returns {Function}
  */
-export function disconnect(requestFeedback: boolean = false) {
+export function disconnect(requestFeedback = false) {
     // XXX For web based version we use conference hanging up logic from the old
     // app.
     return () => APP.conference.hangup(requestFeedback);
diff --git a/react/features/base/connection/constants.js b/react/features/base/connection/constants.ts
similarity index 98%
rename from react/features/base/connection/constants.js
rename to react/features/base/connection/constants.ts
index 895406e239..c8245657ce 100644
--- a/react/features/base/connection/constants.js
+++ b/react/features/base/connection/constants.ts
@@ -1,5 +1,3 @@
-// @flow
-
 /**
  * The name of the {@code JitsiConnection} property which identifies the {@code JitsiConference} currently associated
  * with it.
diff --git a/react/features/base/connection/functions.js b/react/features/base/connection/functions.ts
similarity index 87%
rename from react/features/base/connection/functions.js
rename to react/features/base/connection/functions.ts
index 0af78aa574..2440ef8906 100644
--- a/react/features/base/connection/functions.js
+++ b/react/features/base/connection/functions.ts
@@ -1,7 +1,6 @@
-/* @flow */
-
-import { toState } from '../redux';
-import { toURLString } from '../util';
+import { IStateful } from '../app/types';
+import { toState } from '../redux/functions';
+import { toURLString } from '../util/uri';
 
 import { getURLWithoutParams } from './utils';
 
@@ -13,7 +12,7 @@ import { getURLWithoutParams } from './utils';
  * @returns {string|undefined}
  * @private
  */
-export function getCurrentConferenceUrl(stateful: Function | Object) {
+export function getCurrentConferenceUrl(stateful: IStateful) {
     const state = toState(stateful);
     let currentUrl;
 
@@ -40,7 +39,7 @@ export function getCurrentConferenceUrl(stateful: Function | Object) {
  * to be stripped.
  * @returns {string}
  */
-export function getInviteURL(stateOrGetState: Function | Object): string {
+export function getInviteURL(stateOrGetState: IStateful): string {
     const state = toState(stateOrGetState);
     let locationURL
         = state instanceof URL
@@ -75,7 +74,7 @@ export function getInviteURL(stateOrGetState: Function | Object): string {
  * @param {Function|Object} stateOrGetState - The redux state or redux's {@code getState} function.
  * @returns {boolean}
  */
-export function isInviteURLReady(stateOrGetState: Function | Object): boolean {
+export function isInviteURLReady(stateOrGetState: IStateful): boolean {
     const state = toState(stateOrGetState);
 
     return Boolean(state['features/base/connection'].locationURL || state['features/base/config'].locationURL);
@@ -90,6 +89,6 @@ export function isInviteURLReady(stateOrGetState: Function | Object): boolean {
  * @returns {string} A string in the form of a JID (i.e.
  * {@code user@server.com}).
  */
-export function toJid(id: string, { authdomain, domain }: Object): string {
+export function toJid(id: string, { authdomain, domain }: { authdomain?: string; domain?: string; }): string {
     return id.indexOf('@') >= 0 ? id : `${id}@${authdomain || domain}`;
 }
diff --git a/react/features/base/connection/logger.js b/react/features/base/connection/logger.ts
similarity index 91%
rename from react/features/base/connection/logger.js
rename to react/features/base/connection/logger.ts
index dc234ff788..ab9f232d03 100644
--- a/react/features/base/connection/logger.js
+++ b/react/features/base/connection/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../logging/functions';
 
 export default getLogger('features/base/connection');
diff --git a/react/features/base/devices/actions.js b/react/features/base/devices/actions.ts
similarity index 82%
rename from react/features/base/devices/actions.js
rename to react/features/base/devices/actions.ts
index 3eebe0ec8e..16330b1e31 100644
--- a/react/features/base/devices/actions.js
+++ b/react/features/base/devices/actions.ts
@@ -1,8 +1,7 @@
+import { IStore } from '../../app/types';
 import JitsiMeetJS from '../lib-jitsi-meet';
-import {
-    getUserSelectedOutputDeviceId,
-    updateSettings
-} from '../settings';
+import { updateSettings } from '../settings/actions';
+import { getUserSelectedOutputDeviceId } from '../settings/functions.any';
 
 import {
     ADD_PENDING_DEVICE_REQUEST,
@@ -55,7 +54,7 @@ const DEVICE_TYPE_TO_SETTINGS_KEYS = {
  *      request: Object
  * }}
  */
-export function addPendingDeviceRequest(request) {
+export function addPendingDeviceRequest(request: Object) {
     return {
         type: ADD_PENDING_DEVICE_REQUEST,
         request
@@ -68,7 +67,7 @@ export function addPendingDeviceRequest(request) {
  * @returns {Function}
  */
 export function configureInitialDevices() {
-    return (dispatch, getState) => {
+    return (dispatch: IStore['dispatch'], getState: IStore['getState']) => {
         const deviceLabels = getDevicesFromURL(getState());
         let updateSettingsPromise;
 
@@ -86,9 +85,9 @@ export function configureInitialDevices() {
                             name: 'setDevice',
                             device: {
                                 kind: key.toLowerCase(),
-                                label: deviceLabels[key]
+                                label: deviceLabels[key as keyof typeof deviceLabels]
                             },
-                            // eslint-disable-next-line no-empty-function
+                            // eslint-disable-next-line @typescript-eslint/no-empty-function
                             responseCallback() {}
                         }));
                     });
@@ -96,14 +95,17 @@ export function configureInitialDevices() {
                     return;
                 }
 
-                const newSettings = {};
+                const newSettings: any = {};
 
                 Object.keys(deviceLabels).forEach(key => {
-                    const label = deviceLabels[key];
+                    const label = deviceLabels[key as keyof typeof deviceLabels];
+
+                    // @ts-ignore
                     const deviceId = getDeviceIdByLabel(state, label, key);
 
                     if (deviceId) {
-                        const settingsTranslationMap = DEVICE_TYPE_TO_SETTINGS_KEYS[key];
+                        const settingsTranslationMap = DEVICE_TYPE_TO_SETTINGS_KEYS[
+                            key as keyof typeof DEVICE_TYPE_TO_SETTINGS_KEYS];
 
                         newSettings[settingsTranslationMap.currentDeviceId] = deviceId;
                         newSettings[settingsTranslationMap.userSelectedDeviceId] = deviceId;
@@ -135,12 +137,12 @@ export function configureInitialDevices() {
  * @returns {Function}
  */
 export function getAvailableDevices() {
-    return dispatch => new Promise(resolve => {
+    return (dispatch: IStore['dispatch']) => new Promise(resolve => {
         const { mediaDevices } = JitsiMeetJS;
 
         if (mediaDevices.isDeviceListAvailable()
                 && mediaDevices.isDeviceChangeAvailable()) {
-            mediaDevices.enumerateDevices(devices => {
+            mediaDevices.enumerateDevices((devices: any) => {
                 dispatch(updateDeviceList(devices));
 
                 resolve(devices);
@@ -163,7 +165,7 @@ export function getAvailableDevices() {
  *     error: Object
  * }}
  */
-export function notifyCameraError(error) {
+export function notifyCameraError(error: Error) {
     return {
         type: NOTIFY_CAMERA_ERROR,
         error
@@ -182,7 +184,7 @@ export function notifyCameraError(error) {
  *     error: Object
  * }}
  */
-export function notifyMicError(error) {
+export function notifyMicError(error: Error) {
     return {
         type: NOTIFY_MIC_ERROR,
         error
@@ -211,7 +213,7 @@ export function removePendingDeviceRequests() {
  *      deviceId: string
  * }}
  */
-export function setAudioInputDevice(deviceId) {
+export function setAudioInputDevice(deviceId: string) {
     return {
         type: SET_AUDIO_INPUT_DEVICE,
         deviceId
@@ -225,8 +227,8 @@ export function setAudioInputDevice(deviceId) {
  * @param {string} deviceId - The id of the new audio input device.
  * @returns {Function}
  */
-export function setAudioInputDeviceAndUpdateSettings(deviceId) {
-    return function(dispatch, getState) {
+export function setAudioInputDeviceAndUpdateSettings(deviceId: string) {
+    return function(dispatch: IStore['dispatch'], getState: IStore['getState']) {
         const deviceLabel = getDeviceLabelById(getState(), deviceId, 'audioInput');
 
         dispatch(setAudioInputDevice(deviceId));
@@ -243,8 +245,8 @@ export function setAudioInputDeviceAndUpdateSettings(deviceId) {
  * @param {string} deviceId - The id of the new output device.
  * @returns {Function}
  */
-export function setAudioOutputDevice(deviceId) {
-    return function(dispatch, getState) {
+export function setAudioOutputDevice(deviceId: string) {
+    return function(dispatch: IStore['dispatch'], getState: IStore['getState']) {
         const deviceLabel = getDeviceLabelById(getState(), deviceId, 'audioOutput');
 
         return setAudioOutputDeviceId(deviceId, dispatch, true, deviceLabel);
@@ -260,7 +262,7 @@ export function setAudioOutputDevice(deviceId) {
  *      deviceId: string
  * }}
  */
-export function setVideoInputDevice(deviceId) {
+export function setVideoInputDevice(deviceId: string) {
     return {
         type: SET_VIDEO_INPUT_DEVICE,
         deviceId
@@ -274,8 +276,8 @@ export function setVideoInputDevice(deviceId) {
  * @param {string} deviceId - The id of the new video input device.
  * @returns {Function}
  */
-export function setVideoInputDeviceAndUpdateSettings(deviceId) {
-    return function(dispatch, getState) {
+export function setVideoInputDeviceAndUpdateSettings(deviceId: string) {
+    return function(dispatch: IStore['dispatch'], getState: IStore['getState']) {
         const deviceLabel = getDeviceLabelById(getState(), deviceId, 'videoInput');
 
         dispatch(setVideoInputDevice(deviceId));
@@ -296,7 +298,7 @@ export function setVideoInputDeviceAndUpdateSettings(deviceId) {
  *      devices: Array<MediaDeviceInfo>
  * }}
  */
-export function updateDeviceList(devices) {
+export function updateDeviceList(devices: MediaDeviceInfo[]) {
     return {
         type: UPDATE_DEVICE_LIST,
         devices
@@ -314,7 +316,7 @@ export function updateDeviceList(devices) {
  *      oldDevices: Array<MediaDeviceInfo>
  * }}
  */
-export function checkAndNotifyForNewDevice(newDevices, oldDevices) {
+export function checkAndNotifyForNewDevice(newDevices: MediaDeviceInfo[], oldDevices: MediaDeviceInfo[]) {
     return {
         type: CHECK_AND_NOTIFY_FOR_NEW_DEVICE,
         newDevices,
@@ -331,7 +333,7 @@ export function checkAndNotifyForNewDevice(newDevices, oldDevices) {
  *      permissions: Object
  * }}
  */
-export function devicePermissionsChanged(permissions) {
+export function devicePermissionsChanged(permissions: Object) {
     return {
         type: DEVICE_PERMISSIONS_CHANGED,
         permissions
diff --git a/react/features/base/devices/functions.js b/react/features/base/devices/functions.ts
similarity index 74%
rename from react/features/base/devices/functions.js
rename to react/features/base/devices/functions.ts
index 2782ea0e2e..fda8a36948 100644
--- a/react/features/base/devices/functions.js
+++ b/react/features/base/devices/functions.ts
@@ -1,12 +1,14 @@
-// @flow
-
+import { IState } from '../../app/types';
 import JitsiMeetJS from '../lib-jitsi-meet';
-import { updateSettings } from '../settings';
-import { parseURLParams } from '../util';
+import { updateSettings } from '../settings/actions';
+import { ISettingsState } from '../settings/reducer';
+import { parseURLParams } from '../util/parseURLParams';
 
 import logger from './logger';
+import { IDevicesState } from './reducer';
+
 
-declare var APP: Object;
+declare const APP: any;
 
 const webrtcKindToJitsiKindTranslator = {
     audioinput: 'audioInput',
@@ -22,14 +24,16 @@ const webrtcKindToJitsiKindTranslator = {
  * @returns {boolean} - True if the labels are already initialized and false
  * otherwise.
  */
-export function areDeviceLabelsInitialized(state: Object) {
+export function areDeviceLabelsInitialized(state: IState) {
     // TODO: Replace with something that doesn't use APP when the conference.js logic is reactified.
     if (APP.conference._localTracksInitialized) {
         return true;
     }
 
     for (const type of [ 'audioInput', 'audioOutput', 'videoInput' ]) {
-        if ((state['features/base/devices'].availableDevices[type] || []).find(d => Boolean(d.label))) {
+        const availableDevices = state['features/base/devices'].availableDevices;
+
+        if ((availableDevices[type as keyof typeof availableDevices] || []).find(d => Boolean(d.label))) {
             return true;
         }
     }
@@ -56,14 +60,15 @@ export function getAudioOutputDeviceId() {
  * of the preceding types.
  * @returns {string|undefined}
  */
-export function getDefaultDeviceId(state: Object, kind: string) {
-    const kindToSearch = webrtcKindToJitsiKindTranslator[kind] || kind;
-    const defaultDevice = (state['features/base/devices'].availableDevices[kindToSearch] || [])
+export function getDefaultDeviceId(state: IState, kind: string) {
+    const kindToSearch = webrtcKindToJitsiKindTranslator[kind as keyof typeof webrtcKindToJitsiKindTranslator] || kind;
+    const availableDevices = state['features/base/devices'].availableDevices;
+    const defaultDevice = (availableDevices[kindToSearch as keyof typeof availableDevices] || [])
         .find(d => d.deviceId === 'default');
 
     // Find the device with a matching group id.
-    const matchingDevice = (state['features/base/devices'].availableDevices[kindToSearch] || [])
-        .find(d => d.deviceId !== 'default' && d.groupId === defaultDevice.groupId);
+    const matchingDevice = (availableDevices[kindToSearch as keyof typeof availableDevices] || [])
+        .find(d => d.deviceId !== 'default' && d.groupId === defaultDevice?.groupId);
 
     if (matchingDevice) {
         return matchingDevice.deviceId;
@@ -80,11 +85,12 @@ export function getDefaultDeviceId(state: Object, kind: string) {
  * of the preceding types.
  * @returns {string|undefined}
  */
-export function getDeviceIdByLabel(state: Object, label: string, kind: string) {
-    const kindToSearch = webrtcKindToJitsiKindTranslator[kind] || kind;
+export function getDeviceIdByLabel(state: IState, label: string, kind: string) {
+    const kindToSearch = webrtcKindToJitsiKindTranslator[kind as keyof typeof webrtcKindToJitsiKindTranslator] || kind;
 
+    const availableDevices = state['features/base/devices'].availableDevices;
     const device
-        = (state['features/base/devices'].availableDevices[kindToSearch] || [])
+        = (availableDevices[kindToSearch as keyof typeof availableDevices] || [])
             .find(d => d.label === label);
 
     if (device) {
@@ -102,11 +108,12 @@ export function getDeviceIdByLabel(state: Object, label: string, kind: string) {
  * of the preceding types.
  * @returns {string|undefined}
  */
-export function getDeviceLabelById(state: Object, id: string, kind: string) {
-    const kindToSearch = webrtcKindToJitsiKindTranslator[kind] || kind;
+export function getDeviceLabelById(state: IState, id: string, kind: string) {
+    const kindToSearch = webrtcKindToJitsiKindTranslator[kind as keyof typeof webrtcKindToJitsiKindTranslator] || kind;
 
+    const availableDevices = state['features/base/devices'].availableDevices;
     const device
-        = (state['features/base/devices'].availableDevices[kindToSearch] || [])
+        = (availableDevices[kindToSearch as keyof typeof availableDevices] || [])
         .find(d => d.deviceId === id);
 
     if (device) {
@@ -120,9 +127,9 @@ export function getDeviceLabelById(state: Object, id: string, kind: string) {
  * @param {Object} state - The redux state.
  * @returns {Object|undefined}
  */
-export function getDevicesFromURL(state: Object) {
+export function getDevicesFromURL(state: IState) {
     const urlParams
-        = parseURLParams(state['features/base/connection'].locationURL);
+        = parseURLParams(state['features/base/connection'].locationURL ?? '');
 
     const audioOutput = urlParams['devices.audioOutput'];
     const videoInput = urlParams['devices.videoInput'];
@@ -132,7 +139,7 @@ export function getDevicesFromURL(state: Object) {
         return undefined;
     }
 
-    const devices = {};
+    const devices: IDevicesState['availableDevices'] = {};
 
     audioOutput && (devices.audioOutput = audioOutput);
     videoInput && (devices.videoInput = videoInput);
@@ -150,7 +157,7 @@ export function getDevicesFromURL(state: Object) {
  * are device type and the values are arrays with devices matching the device
  * type.
  */
-export function groupDevicesByKind(devices: Object[]): Object {
+export function groupDevicesByKind(devices: MediaDeviceInfo[]): IDevicesState['availableDevices'] {
     return {
         audioInput: devices.filter(device => device.kind === 'audioinput'),
         audioOutput: devices.filter(device => device.kind === 'audiooutput'),
@@ -165,7 +172,7 @@ export function groupDevicesByKind(devices: Object[]): Object {
  * @private
  * @returns {Array<MediaDeviceInfo>} Filtered audio devices.
  */
-export function filterAudioDevices(devices: Object[]): Object {
+export function filterAudioDevices(devices: MediaDeviceInfo[]) {
     return devices.filter(device => device.kind === 'audioinput');
 }
 
@@ -197,8 +204,8 @@ export function formatDeviceLabel(label: string) {
  * @param {Object} state - The state of the application.
  * @returns {Object[]}
  */
-export function getAudioInputDeviceData(state: Object) {
-    return state['features/base/devices'].availableDevices.audioInput.map(
+export function getAudioInputDeviceData(state: IState) {
+    return state['features/base/devices'].availableDevices.audioInput?.map(
         ({ deviceId, label }) => {
             return {
                 deviceId,
@@ -213,8 +220,8 @@ export function getAudioInputDeviceData(state: Object) {
  * @param {Object} state - The state of the application.
  * @returns {Object[]}
  */
-export function getAudioOutputDeviceData(state: Object) {
-    return state['features/base/devices'].availableDevices.audioOutput.map(
+export function getAudioOutputDeviceData(state: IState) {
+    return state['features/base/devices'].availableDevices.audioOutput?.map(
         ({ deviceId, label }) => {
             return {
                 deviceId,
@@ -229,8 +236,8 @@ export function getAudioOutputDeviceData(state: Object) {
  * @param {Object} state - The state of the application.
  * @returns {string[]}
  */
-export function getVideoDeviceIds(state: Object) {
-    return state['features/base/devices'].availableDevices.videoInput.map(({ deviceId }) => deviceId);
+export function getVideoDeviceIds(state: IState) {
+    return state['features/base/devices'].availableDevices.videoInput?.map(({ deviceId }) => deviceId);
 }
 
 /**
@@ -241,12 +248,14 @@ export function getVideoDeviceIds(state: Object) {
  *
  * @returns {boolean}
  */
-export function hasAvailableDevices(state: Object, type: string) {
+export function hasAvailableDevices(state: IState, type: string) {
     if (state['features/base/devices'] === undefined) {
         return true;
     }
 
-    return state['features/base/devices'].availableDevices[type].length > 0;
+    const availableDevices = state['features/base/devices'].availableDevices;
+
+    return Number(availableDevices[type as keyof typeof availableDevices]?.length) > 0;
 }
 
 /**
@@ -260,10 +269,10 @@ export function hasAvailableDevices(state: Object, type: string) {
  * @returns {Promise}
  */
 export function setAudioOutputDeviceId(
-        newId: string = 'default',
+        newId = 'default',
         dispatch: Function,
-        userSelection: boolean = false,
-        newLabel: ?string): Promise<*> {
+        userSelection = false,
+        newLabel?: string): Promise<any> {
 
     logger.debug(`setAudioOutputDevice: ${String(newLabel)}[${newId}]`);
 
@@ -275,7 +284,7 @@ export function setAudioOutputDeviceId(
 
     return JitsiMeetJS.mediaDevices.setAudioOutputDevice(newId)
         .then(() => {
-            const newSettings = {
+            const newSettings: Partial<ISettingsState> = {
                 audioOutputDeviceId: newId,
                 userSelectedAudioOutputDeviceId: undefined,
                 userSelectedAudioOutputDeviceLabel: undefined
diff --git a/react/features/base/devices/reducer.ts b/react/features/base/devices/reducer.ts
index 293240c8c5..39ab4c0a44 100644
--- a/react/features/base/devices/reducer.ts
+++ b/react/features/base/devices/reducer.ts
@@ -29,9 +29,9 @@ const DEFAULT_STATE: IDevicesState = {
 
 export interface IDevicesState {
     availableDevices: {
-        audioInput: MediaDeviceInfo[];
-        audioOutput: MediaDeviceInfo[];
-        videoInput: MediaDeviceInfo[];
+        audioInput?: MediaDeviceInfo[];
+        audioOutput?: MediaDeviceInfo[];
+        videoInput?: MediaDeviceInfo[];
     };
     pendingRequests: Object[];
     permissions: {
diff --git a/react/features/base/flags/actions.js b/react/features/base/flags/actions.ts
similarity index 97%
rename from react/features/base/flags/actions.js
rename to react/features/base/flags/actions.ts
index e99f64c1bb..457a840086 100644
--- a/react/features/base/flags/actions.js
+++ b/react/features/base/flags/actions.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { UPDATE_FLAGS } from './actionTypes';
 
 /**
diff --git a/react/features/base/flags/constants.js b/react/features/base/flags/constants.ts
similarity index 100%
rename from react/features/base/flags/constants.js
rename to react/features/base/flags/constants.ts
diff --git a/react/features/base/flags/functions.js b/react/features/base/flags/functions.ts
similarity index 77%
rename from react/features/base/flags/functions.js
rename to react/features/base/flags/functions.ts
index a3c0aadcc0..c5e16fb1b1 100644
--- a/react/features/base/flags/functions.js
+++ b/react/features/base/flags/functions.ts
@@ -1,7 +1,7 @@
-// @flow
-
+// @ts-ignore
 import { getAppProp } from '../app';
-import { toState } from '../redux';
+import { IStateful } from '../app/types';
+import { toState } from '../redux/functions';
 
 /**
  * Gets the value of a specific feature flag.
@@ -14,11 +14,11 @@ import { toState } from '../redux';
  * @returns {*} The value of the specified React {@code Component} prop of the
  * currently mounted {@code App}.
  */
-export function getFeatureFlag(stateful: Function | Object, flag: string, defaultValue: any) {
+export function getFeatureFlag(stateful: IStateful, flag: string, defaultValue?: any) {
     const state = toState(stateful)['features/base/flags'];
 
     if (state) {
-        const value = state[flag];
+        const value = state[flag as keyof typeof state];
 
         if (typeof value !== 'undefined') {
             return value;
diff --git a/react/features/base/known-domains/actions.js b/react/features/base/known-domains/actions.ts
similarity index 98%
rename from react/features/base/known-domains/actions.js
rename to react/features/base/known-domains/actions.ts
index aac8c5bdf5..d534512a81 100644
--- a/react/features/base/known-domains/actions.js
+++ b/react/features/base/known-domains/actions.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { ADD_KNOWN_DOMAINS } from './actionTypes';
 
 /**
diff --git a/react/features/base/known-domains/middleware.js b/react/features/base/known-domains/middleware.ts
similarity index 70%
rename from react/features/base/known-domains/middleware.js
rename to react/features/base/known-domains/middleware.ts
index e04cca9ac8..d742c6fb69 100644
--- a/react/features/base/known-domains/middleware.js
+++ b/react/features/base/known-domains/middleware.ts
@@ -1,10 +1,10 @@
-// @flow
-
+// @ts-ignore
 import { getDefaultURL } from '../../app/functions';
-import { APP_WILL_MOUNT } from '../app';
-import { SET_ROOM } from '../conference';
-import { MiddlewareRegistry } from '../redux';
-import { parseURIString } from '../util';
+import { IStore } from '../../app/types';
+import { APP_WILL_MOUNT } from '../app/actionTypes';
+import { SET_ROOM } from '../conference/actionTypes';
+import MiddlewareRegistry from '../redux/MiddlewareRegistry';
+import { parseURIString } from '../util/uri';
 
 import { addKnownDomains } from './actions';
 
@@ -32,10 +32,10 @@ MiddlewareRegistry.register(store => next => action => {
  * @private
  * @returns {Promise}
  */
-function _appWillMount({ dispatch, getState }) {
+function _appWillMount({ dispatch, getState }: IStore) {
     const defaultURL = parseURIString(getDefaultURL(getState));
 
-    dispatch(addKnownDomains(defaultURL.host));
+    dispatch(addKnownDomains(defaultURL?.host));
 }
 
 /**
@@ -46,7 +46,7 @@ function _appWillMount({ dispatch, getState }) {
  * @private
  * @returns {Promise}
  */
-function _setRoom({ dispatch, getState }) {
+function _setRoom({ dispatch, getState }: IStore) {
     const { locationURL } = getState()['features/base/connection'];
     let host;
 
diff --git a/react/features/base/media/functions.js b/react/features/base/media/functions.ts
similarity index 87%
rename from react/features/base/media/functions.js
rename to react/features/base/media/functions.ts
index d02b0aacf8..da337637f8 100644
--- a/react/features/base/media/functions.js
+++ b/react/features/base/media/functions.ts
@@ -1,7 +1,6 @@
-/* @flow */
-
-import { toState } from '../redux';
-import { getPropertyValue } from '../settings';
+import { IStateful } from '../app/types';
+import { toState } from '../redux/functions';
+import { getPropertyValue } from '../settings/functions.any';
 
 import { VIDEO_MUTISM_AUTHORITY } from './constants';
 
@@ -32,7 +31,7 @@ const START_WITH_AUDIO_VIDEO_MUTED_SOURCES = {
  * {@code getState} function.
  * @returns {boolean}
  */
-export function isAudioMuted(stateful: Function | Object) {
+export function isAudioMuted(stateful: IStateful) {
     return Boolean(toState(stateful)['features/base/media'].audio.muted);
 }
 
@@ -43,7 +42,7 @@ export function isAudioMuted(stateful: Function | Object) {
  * {@code getState} function.
  * @returns {boolean}
  */
-export function isVideoMutedByAudioOnly(stateful: Function | Object) {
+export function isVideoMutedByAudioOnly(stateful: IStateful) {
     return (
         _isVideoMutedByAuthority(stateful, VIDEO_MUTISM_AUTHORITY.AUDIO_ONLY));
 }
@@ -60,7 +59,7 @@ export function isVideoMutedByAudioOnly(stateful: Function | Object) {
  * {@code videoMutismAuthority}, then {@code true}; otherwise, {@code false}.
  */
 function _isVideoMutedByAuthority(
-        stateful: Function | Object,
+        stateful: IStateful,
         videoMutismAuthority: number) {
     const { muted } = toState(stateful)['features/base/media'].video;
 
@@ -74,7 +73,7 @@ function _isVideoMutedByAuthority(
  * @param {Object|Function} stateful - The redux state object or {@code getState} function.
  * @returns {boolean} - The computed startWithAudioMuted value that will be used.
  */
-export function getStartWithAudioMuted(stateful: Object | Function) {
+export function getStartWithAudioMuted(stateful: IStateful) {
     return Boolean(getPropertyValue(stateful, 'startWithAudioMuted', START_WITH_AUDIO_VIDEO_MUTED_SOURCES));
 }
 
@@ -84,7 +83,7 @@ export function getStartWithAudioMuted(stateful: Object | Function) {
  * @param {Object|Function} stateful - The redux state object or {@code getState} function.
  * @returns {boolean} - The computed startWithVideoMuted value that will be used.
  */
-export function getStartWithVideoMuted(stateful: Object | Function) {
+export function getStartWithVideoMuted(stateful: IStateful) {
     return Boolean(getPropertyValue(stateful, 'startWithVideoMuted', START_WITH_AUDIO_VIDEO_MUTED_SOURCES));
 }
 
@@ -94,7 +93,7 @@ export function getStartWithVideoMuted(stateful: Object | Function) {
  * @param {Function|Object} stateful - The redux store, state, or {@code getState} function.
  * @returns {boolean}
  */
-export function isVideoMuted(stateful: Function | Object) {
+export function isVideoMuted(stateful: IStateful) {
     return Boolean(toState(stateful)['features/base/media'].video.muted);
 }
 
@@ -105,7 +104,7 @@ export function isVideoMuted(stateful: Function | Object) {
  * {@code getState} function.
  * @returns {boolean}
  */
-export function isVideoMutedByUser(stateful: Function | Object) {
+export function isVideoMutedByUser(stateful: IStateful) {
     return _isVideoMutedByAuthority(stateful, VIDEO_MUTISM_AUTHORITY.USER);
 }
 
@@ -120,7 +119,7 @@ export function isVideoMutedByUser(stateful: Function | Object) {
  * otherwise, false.
  */
 export function shouldRenderVideoTrack(
-        videoTrack: ?{ muted: boolean, videoStarted: boolean },
+        videoTrack: { muted: boolean; videoStarted: boolean; },
         waitForVideoStarted: boolean) {
     return (
         videoTrack
diff --git a/react/features/base/media/logger.js b/react/features/base/media/logger.ts
similarity index 90%
rename from react/features/base/media/logger.js
rename to react/features/base/media/logger.ts
index 6468f3e4ed..e89c863252 100644
--- a/react/features/base/media/logger.js
+++ b/react/features/base/media/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../logging/functions';
 
 export default getLogger('features/base/media');
diff --git a/react/features/base/participants/functions.ts b/react/features/base/participants/functions.ts
index a076fb11bb..a2b0dabb46 100644
--- a/react/features/base/participants/functions.ts
+++ b/react/features/base/participants/functions.ts
@@ -80,16 +80,16 @@ export function getActiveSpeakersToBeDisplayed(stateful: IStateful) {
     }
     let availableSlotsForActiveSpeakers = visibleRemoteParticipants.size;
 
-    if (activeSpeakers.has(dominantSpeaker)) {
-        activeSpeakers.delete(dominantSpeaker);
+    if (activeSpeakers.has(dominantSpeaker ?? '')) {
+        activeSpeakers.delete(dominantSpeaker ?? '');
     }
 
     // Add dominant speaker to the beginning of the list (not including self) since the active speaker list is always
     // alphabetically sorted.
-    if (dominantSpeaker && dominantSpeaker !== getLocalParticipant(state).id) {
+    if (dominantSpeaker && dominantSpeaker !== getLocalParticipant(state)?.id) {
         const updatedSpeakers = Array.from(activeSpeakers);
 
-        updatedSpeakers.splice(0, 0, [ dominantSpeaker, getParticipantById(state, dominantSpeaker)?.name ]);
+        updatedSpeakers.splice(0, 0, [ dominantSpeaker, getParticipantById(state, dominantSpeaker)?.name ?? '' ]);
         activeSpeakers = new Map(updatedSpeakers);
     }
 
@@ -359,11 +359,11 @@ export function getParticipantDisplayName(stateful: IStateful, id: string): stri
         }
 
         if (participant.local) {
-            return defaultLocalDisplayName;
+            return defaultLocalDisplayName ?? '';
         }
     }
 
-    return defaultRemoteDisplayName;
+    return defaultRemoteDisplayName ?? '';
 }
 
 /**
@@ -439,7 +439,7 @@ export function getPinnedParticipant(stateful: IStateful) {
 
     if (stageFilmstrip) {
         const { activeParticipants } = state['features/filmstrip'];
-        const id = activeParticipants.find((p: Participant) => p.pinned)?.participantId;
+        const id = activeParticipants.find(p => p.pinned)?.participantId;
 
         return id ? getParticipantById(stateful, id) : undefined;
     }
diff --git a/react/features/base/participants/types.ts b/react/features/base/participants/types.ts
index 7343b823df..3ac619859e 100644
--- a/react/features/base/participants/types.ts
+++ b/react/features/base/participants/types.ts
@@ -30,6 +30,7 @@ export interface Participant {
 export interface LocalParticipant extends Participant {
     audioOutputDeviceId?: string;
     cameraDeviceId?: string;
+    jwtId?: string;
     micDeviceId?: string;
     startWithAudioMuted?: boolean;
     startWithVideoMuted?: boolean;
diff --git a/react/features/base/redux/functions.ts b/react/features/base/redux/functions.ts
index d7dd9ae120..1008021342 100644
--- a/react/features/base/redux/functions.ts
+++ b/react/features/base/redux/functions.ts
@@ -1,6 +1,7 @@
 import _ from 'lodash';
 import { connect as reduxConnect } from 'react-redux';
 
+import { IState } from '../../app/types';
 import { IStateful } from '../app/types';
 
 /**
@@ -135,7 +136,7 @@ function _set<T extends Object>(
  * returned.
  * @returns {Object} The redux state.
  */
-export function toState(stateful: IStateful) {
+export function toState(stateful: IStateful): IState {
     if (stateful) {
         if (typeof stateful === 'function') {
             return stateful();
@@ -149,5 +150,6 @@ export function toState(stateful: IStateful) {
         }
     }
 
+    // @ts-ignore
     return stateful;
 }
diff --git a/react/features/base/redux/middleware.js b/react/features/base/redux/middleware.ts
similarity index 99%
rename from react/features/base/redux/middleware.js
rename to react/features/base/redux/middleware.ts
index e1aa95b65f..2dbb8f760c 100644
--- a/react/features/base/redux/middleware.js
+++ b/react/features/base/redux/middleware.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import _ from 'lodash';
 
 import MiddlewareRegistry from './MiddlewareRegistry';
diff --git a/react/features/base/settings/actions.js b/react/features/base/settings/actions.ts
similarity index 87%
rename from react/features/base/settings/actions.js
rename to react/features/base/settings/actions.ts
index 0d195ccc77..aeb91eb569 100644
--- a/react/features/base/settings/actions.js
+++ b/react/features/base/settings/actions.ts
@@ -1,4 +1,5 @@
 import { SETTINGS_UPDATED } from './actionTypes';
+import { ISettingsState } from './reducer';
 
 /**
  * Create an action for when the settings are updated.
@@ -23,7 +24,7 @@ import { SETTINGS_UPDATED } from './actionTypes';
  *     }
  * }}
  */
-export function updateSettings(settings) {
+export function updateSettings(settings: Partial<ISettingsState>) {
     return {
         type: SETTINGS_UPDATED,
         settings
diff --git a/react/features/base/settings/constants.js b/react/features/base/settings/constants.ts
similarity index 92%
rename from react/features/base/settings/constants.js
rename to react/features/base/settings/constants.ts
index 7cbbd98483..2cbd65d852 100644
--- a/react/features/base/settings/constants.js
+++ b/react/features/base/settings/constants.ts
@@ -1,5 +1,3 @@
-// @flow
-
 /**
  * The default server URL to open if no other was specified.
  */
diff --git a/react/features/base/settings/functions.any.js b/react/features/base/settings/functions.any.ts
similarity index 83%
rename from react/features/base/settings/functions.any.js
rename to react/features/base/settings/functions.any.ts
index 1a4a03c661..47b75fe092 100644
--- a/react/features/base/settings/functions.any.js
+++ b/react/features/base/settings/functions.any.ts
@@ -1,10 +1,14 @@
-// @flow
-import { CONFIG_WHITELIST } from '../config';
-import { getParticipantCount } from '../participants';
-import { toState } from '../redux';
-import { parseURLParams } from '../util';
+import { IState } from '../../app/types';
+import { IStateful } from '../app/types';
+import CONFIG_WHITELIST from '../config/configWhitelist';
+import { IConfigState } from '../config/reducer';
+import { IJwtState } from '../jwt/reducer';
+import { getParticipantCount } from '../participants/functions';
+import { toState } from '../redux/functions';
+import { parseURLParams } from '../util/parseURLParams';
 
 import { DEFAULT_SERVER_URL } from './constants';
+import { ISettingsState } from './reducer';
 
 /**
  * Returns the effective value of a configuration/preference/setting by applying
@@ -23,9 +27,9 @@ import { DEFAULT_SERVER_URL } from './constants';
  * @returns {any}
  */
 export function getPropertyValue(
-        stateful: Object | Function,
+        stateful: IStateful,
         propertyName: string,
-        sources?: Object
+        sources?: any
 ) {
     // Default values don't play nicely with partial objects and we want to make
     // the function easy to use without exhaustively defining all flags:
@@ -45,10 +49,10 @@ export function getPropertyValue(
 
     // jwt
     if (sources.jwt) {
-        const value = state['features/base/jwt'][propertyName];
+        const value = state['features/base/jwt'][propertyName as keyof IJwtState];
 
         if (typeof value !== 'undefined') {
-            return value[propertyName];
+            return value[propertyName as keyof typeof value];
         }
     }
 
@@ -56,7 +60,7 @@ export function getPropertyValue(
     if (sources.urlParams) {
         if (CONFIG_WHITELIST.indexOf(propertyName) !== -1) {
             const urlParams
-                = parseURLParams(state['features/base/connection'].locationURL);
+                = parseURLParams(state['features/base/connection'].locationURL ?? '');
             const value = urlParams[`config.${propertyName}`];
 
             if (typeof value !== 'undefined') {
@@ -67,7 +71,7 @@ export function getPropertyValue(
 
     // settings
     if (sources.settings) {
-        const value = state['features/base/settings'][propertyName];
+        const value = state['features/base/settings'][propertyName as keyof ISettingsState];
 
         if (typeof value !== 'undefined') {
             return value;
@@ -76,7 +80,7 @@ export function getPropertyValue(
 
     // config
     if (sources.config) {
-        const value = state['features/base/config'][propertyName];
+        const value = state['features/base/config'][propertyName as keyof IConfigState];
 
         if (typeof value !== 'undefined') {
             return value;
@@ -93,7 +97,7 @@ export function getPropertyValue(
  * {@code getState} function.
  * @returns {string} - The currently configured server URL.
  */
-export function getServerURL(stateful: Object | Function) {
+export function getServerURL(stateful: IStateful) {
     const state = toState(stateful);
 
     return state['features/base/settings'].serverURL || DEFAULT_SERVER_URL;
@@ -107,7 +111,7 @@ export function getServerURL(stateful: Object | Function) {
  * {@code getState} function.
  * @returns {string}
  */
-export function getUserSelectedCameraDeviceId(stateful: Object | Function) {
+export function getUserSelectedCameraDeviceId(stateful: IStateful) {
     const state = toState(stateful);
     const {
         userSelectedCameraDeviceId,
@@ -135,7 +139,7 @@ export function getUserSelectedCameraDeviceId(stateful: Object | Function) {
  * {@code getState} function.
  * @returns {string}
  */
-export function getUserSelectedMicDeviceId(stateful: Object | Function) {
+export function getUserSelectedMicDeviceId(stateful: IStateful) {
     const state = toState(stateful);
     const {
         userSelectedMicDeviceId,
@@ -163,7 +167,7 @@ export function getUserSelectedMicDeviceId(stateful: Object | Function) {
  * {@code getState} function.
  * @returns {string}
  */
-export function getUserSelectedOutputDeviceId(stateful: Object | Function) {
+export function getUserSelectedOutputDeviceId(stateful: IStateful) {
     const state = toState(stateful);
     const {
         userSelectedAudioOutputDeviceId,
@@ -202,13 +206,19 @@ export function getUserSelectedOutputDeviceId(stateful: Object | Function) {
  * @private
  * @returns {string} The preferred device ID to use for media.
  */
-function _getUserSelectedDeviceId(options) {
+function _getUserSelectedDeviceId(options: {
+    availableDevices: MediaDeviceInfo[] | undefined;
+    matchRegex?: RegExp;
+    replacement?: string;
+    userSelectedDeviceId?: string;
+    userSelectedDeviceLabel?: string;
+}) {
     const {
         availableDevices,
-        matchRegex,
+        matchRegex = '',
         userSelectedDeviceId,
         userSelectedDeviceLabel,
-        replacement
+        replacement = ''
     } = options;
 
     // If there is no label at all, there is no need to fall back to checking
@@ -217,7 +227,7 @@ function _getUserSelectedDeviceId(options) {
         return userSelectedDeviceId;
     }
 
-    const foundMatchingBasedonDeviceId = availableDevices.find(
+    const foundMatchingBasedonDeviceId = availableDevices?.find(
         candidate => candidate.deviceId === userSelectedDeviceId);
 
     // Prioritize matching the deviceId
@@ -228,7 +238,7 @@ function _getUserSelectedDeviceId(options) {
     const strippedDeviceLabel
         = matchRegex ? userSelectedDeviceLabel.replace(matchRegex, replacement)
             : userSelectedDeviceLabel;
-    const foundMatchBasedOnLabel = availableDevices.find(candidate => {
+    const foundMatchBasedOnLabel = availableDevices?.find(candidate => {
         const { label } = candidate;
 
         if (!label) {
@@ -253,7 +263,7 @@ function _getUserSelectedDeviceId(options) {
  * @param {Object} state - The state of the application.
  * @returns {boolean}
  */
-export function shouldHideShareAudioHelper(state: Object): boolean {
+export function shouldHideShareAudioHelper(state: IState): boolean | undefined {
 
     return state['features/base/settings'].hideShareAudioHelper;
 }
@@ -264,7 +274,7 @@ export function shouldHideShareAudioHelper(state: Object): boolean {
  * @param {Object} state - Redux state.
  * @returns {boolean}
  */
-export function shouldHideSelfView(state: Object) {
+export function shouldHideSelfView(state: IState) {
     return getParticipantCount(state) === 1 ? false : getHideSelfView(state);
 }
 
@@ -274,6 +284,6 @@ export function shouldHideSelfView(state: Object) {
  * @param {Object} state - Redux state.
  * @returns {boolean}
  */
-export function getHideSelfView(state: Object) {
+export function getHideSelfView(state: IState) {
     return state['features/base/config'].disableSelfView || state['features/base/settings'].disableSelfView;
 }
diff --git a/react/features/base/settings/functions.native.js b/react/features/base/settings/functions.native.ts
similarity index 98%
rename from react/features/base/settings/functions.native.js
rename to react/features/base/settings/functions.native.ts
index e7c563ab71..f6f8907e14 100644
--- a/react/features/base/settings/functions.native.js
+++ b/react/features/base/settings/functions.native.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { NativeModules } from 'react-native';
 import DefaultPreference from 'react-native-default-preference';
 
@@ -31,6 +29,6 @@ export function handleCallIntegrationChange(disabled: boolean) {
  * @returns {void}
  */
 export function handleCrashReportingChange(disabled: boolean) {
-    DefaultPreference.setName('jitsi-default-preferences').then(
+    DefaultPreference.setName('jitsi-default-preferences').then( // @ts-ignore
         DefaultPreference.set('isCrashReportingDisabled', disabled.toString()));
 }
diff --git a/react/features/base/settings/functions.web.js b/react/features/base/settings/functions.web.ts
similarity index 70%
rename from react/features/base/settings/functions.web.js
rename to react/features/base/settings/functions.web.ts
index da8668a72f..0819fba6f1 100644
--- a/react/features/base/settings/functions.web.js
+++ b/react/features/base/settings/functions.web.ts
@@ -1,4 +1,5 @@
-// @flow
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import { IState } from '../../app/types';
 
 export * from './functions.any';
 
@@ -8,7 +9,7 @@ export * from './functions.any';
  * @param {Object} state - The state of the application.
  * @returns {void}
  */
-export function getCurrentCameraDeviceId(state: Object) {
+export function getCurrentCameraDeviceId(state: IState) {
     return getDeviceIdByType(state, 'isVideoTrack');
 }
 
@@ -18,7 +19,7 @@ export function getCurrentCameraDeviceId(state: Object) {
  * @param {Object} state - The state of the application.
  * @returns {void}
  */
-export function getCurrentMicDeviceId(state: Object) {
+export function getCurrentMicDeviceId(state: IState) {
     return getDeviceIdByType(state, 'isAudioTrack');
 }
 
@@ -28,7 +29,7 @@ export function getCurrentMicDeviceId(state: Object) {
  * @param {Object} state - The state of the application.
  * @returns {void}
  */
-export function getCurrentOutputDeviceId(state: Object) {
+export function getCurrentOutputDeviceId(state: IState) {
     return state['features/base/settings'].audioOutputDeviceId;
 }
 
@@ -39,11 +40,11 @@ export function getCurrentOutputDeviceId(state: Object) {
  * @param {string} isType - Can be 'isVideoTrack' | 'isAudioTrack'.
  * @returns {string}
  */
-function getDeviceIdByType(state: Object, isType: string) {
+function getDeviceIdByType(state: IState, isType: string) {
     const [ deviceId ] = state['features/base/tracks']
-          .map(t => t.jitsiTrack)
-          .filter(t => t && t.isLocal() && t[isType]())
-          .map(t => t.getDeviceId());
+        .map(t => t.jitsiTrack)
+        .filter(t => t?.isLocal() && t[isType as keyof typeof t]())
+        .map(t => t.getDeviceId());
 
     return deviceId || '';
 }
@@ -54,7 +55,7 @@ function getDeviceIdByType(state: Object, isType: string) {
  * @param {Object} state - The state of the application.
  * @returns {string}
  */
-export function getDisplayName(state: Object): string {
+export function getDisplayName(state: IState): string {
     return state['features/base/settings'].displayName || '';
 }
 
@@ -66,8 +67,8 @@ export function getDisplayName(state: Object): string {
  * @param {boolean} disabled - Whether call integration is disabled or not.
  * @returns {void}
  */
-export function handleCallIntegrationChange(disabled: boolean) { // eslint-disable-line no-unused-vars
-}
+// eslint-disable-next-line @typescript-eslint/no-empty-function, require-jsdoc
+export function handleCallIntegrationChange(disabled: boolean) { }
 
 /**
  * Handles changes to the `disableCrashReporting` setting.
@@ -76,5 +77,5 @@ export function handleCallIntegrationChange(disabled: boolean) { // eslint-disab
  * @param {boolean} disabled - Whether crash reporting is disabled or not.
  * @returns {void}
  */
-export function handleCrashReportingChange(disabled: boolean) { // eslint-disable-line no-unused-vars
-}
+// eslint-disable-next-line @typescript-eslint/no-empty-function, require-jsdoc
+export function handleCrashReportingChange(disabled: boolean) { }
diff --git a/react/features/base/settings/logger.js b/react/features/base/settings/logger.ts
similarity index 91%
rename from react/features/base/settings/logger.js
rename to react/features/base/settings/logger.ts
index 824bcf3e96..84b91a66c2 100644
--- a/react/features/base/settings/logger.js
+++ b/react/features/base/settings/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../logging/functions';
 
 export default getLogger('features/base/settings');
diff --git a/react/features/base/settings/middleware.js b/react/features/base/settings/middleware.ts
similarity index 79%
rename from react/features/base/settings/middleware.js
rename to react/features/base/settings/middleware.ts
index c6d1f1a70b..d76491873d 100644
--- a/react/features/base/settings/middleware.js
+++ b/react/features/base/settings/middleware.ts
@@ -1,19 +1,26 @@
-// @flow
+/* eslint-disable lines-around-comment */
 import _ from 'lodash';
+import { AnyAction } from 'redux';
 
+import { IStore } from '../../app/types';
 import { PREJOIN_INITIALIZED } from '../../prejoin/actionTypes';
+// @ts-ignore
 import { setPrejoinPageVisibility } from '../../prejoin/actions';
-import { APP_WILL_MOUNT } from '../app';
-import { setAudioOnly } from '../audio-only';
+import { APP_WILL_MOUNT } from '../app/actionTypes';
+import { setAudioOnly } from '../audio-only/actions';
 import { SET_LOCATION_URL } from '../connection/actionTypes'; // minimize imports to avoid circular imports
+// @ts-ignore
 import { getJwtName } from '../jwt/functions';
-import { getLocalParticipant, participantUpdated } from '../participants';
-import { MiddlewareRegistry } from '../redux';
-import { parseURLParams } from '../util';
+import { participantUpdated } from '../participants/actions';
+import { getLocalParticipant } from '../participants/functions';
+import MiddlewareRegistry from '../redux/MiddlewareRegistry';
+import { parseURLParams } from '../util/parseURLParams';
 
 import { SETTINGS_UPDATED } from './actionTypes';
 import { updateSettings } from './actions';
+// @ts-ignore
 import { handleCallIntegrationChange, handleCrashReportingChange } from './functions';
+import { ISettingsState } from './reducer';
 
 
 /**
@@ -57,7 +64,7 @@ MiddlewareRegistry.register(store => next => action => {
  * @private
  * @returns {void}
  */
-function _initializeShowPrejoin({ dispatch, getState }) {
+function _initializeShowPrejoin({ dispatch, getState }: IStore) {
     const { userSelectedSkipPrejoin } = getState()['features/base/settings'];
 
     if (userSelectedSkipPrejoin) {
@@ -72,7 +79,7 @@ function _initializeShowPrejoin({ dispatch, getState }) {
  * @private
  * @returns {void}
  */
-function _initializeCallIntegration({ getState }) {
+function _initializeCallIntegration({ getState }: IStore) {
     const { disableCallIntegration } = getState()['features/base/settings'];
 
     if (typeof disableCallIntegration === 'boolean') {
@@ -88,7 +95,7 @@ function _initializeCallIntegration({ getState }) {
  * @param {string} settingsField - The name of the settings field to map.
  * @returns {string}
  */
-function _mapSettingsFieldToParticipant(settingsField) {
+function _mapSettingsFieldToParticipant(settingsField: string) {
     switch (settingsField) {
     case 'displayName':
         return 'name';
@@ -104,7 +111,9 @@ function _mapSettingsFieldToParticipant(settingsField) {
  * @private
  * @returns {void}
  */
-function _maybeHandleCallIntegrationChange({ settings: { disableCallIntegration } }) {
+function _maybeHandleCallIntegrationChange({ settings: { disableCallIntegration } }: {
+    settings: Partial<ISettingsState>;
+}) {
     if (typeof disableCallIntegration === 'boolean') {
         handleCallIntegrationChange(disableCallIntegration);
     }
@@ -117,7 +126,9 @@ function _maybeHandleCallIntegrationChange({ settings: { disableCallIntegration
  * @private
  * @returns {void}
  */
-function _maybeCrashReportingChange({ settings: { disableCrashReporting } }) {
+function _maybeCrashReportingChange({ settings: { disableCrashReporting } }: {
+    settings: Partial<ISettingsState>;
+}) {
     if (typeof disableCrashReporting === 'boolean') {
         handleCrashReportingChange(disableCrashReporting);
     }
@@ -132,8 +143,8 @@ function _maybeCrashReportingChange({ settings: { disableCrashReporting } }) {
  * @returns {void}
  */
 function _maybeSetAudioOnly(
-        { dispatch },
-        { settings: { startAudioOnly } }) {
+        { dispatch }: IStore,
+        { settings: { startAudioOnly } }: { settings: Partial<ISettingsState>; }) {
     if (typeof startAudioOnly === 'boolean') {
         dispatch(setAudioOnly(startAudioOnly));
     }
@@ -146,7 +157,7 @@ function _maybeSetAudioOnly(
  * @private
  * @returns {void}
  */
-function _maybeUpdateDisplayName({ dispatch, getState }) {
+function _maybeUpdateDisplayName({ dispatch, getState }: IStore) {
     const state = getState();
     const hasJwt = Boolean(state['features/base/jwt'].jwt);
 
@@ -169,7 +180,7 @@ function _maybeUpdateDisplayName({ dispatch, getState }) {
  * @private
  * @returns {void}
  */
-function _updateLocalParticipant({ dispatch, getState }, action) {
+function _updateLocalParticipant({ dispatch, getState }: IStore, action: AnyAction) {
     const { settings } = action;
     const localParticipant = getLocalParticipant(getState());
     const newLocalParticipant = {
@@ -178,12 +189,15 @@ function _updateLocalParticipant({ dispatch, getState }, action) {
 
     for (const key in settings) {
         if (settings.hasOwnProperty(key)) {
-            newLocalParticipant[_mapSettingsFieldToParticipant(key)]
+            newLocalParticipant[_mapSettingsFieldToParticipant(key) as keyof typeof newLocalParticipant]
                 = settings[key];
         }
     }
 
-    dispatch(participantUpdated(newLocalParticipant));
+    dispatch(participantUpdated({
+        ...newLocalParticipant,
+        id: newLocalParticipant.id ?? ''
+    }));
 }
 
 
@@ -194,9 +208,9 @@ function _updateLocalParticipant({ dispatch, getState }, action) {
  * @private
  * @returns {void}
  */
-function _updateLocalParticipantFromUrl({ dispatch, getState }) {
+function _updateLocalParticipantFromUrl({ dispatch, getState }: IStore) {
     const urlParams
-        = parseURLParams(getState()['features/base/connection'].locationURL);
+        = parseURLParams(getState()['features/base/connection'].locationURL ?? '');
     const urlEmail = urlParams['userInfo.email'];
     const urlDisplayName = urlParams['userInfo.displayName'];
 
diff --git a/react/features/base/settings/reducer.ts b/react/features/base/settings/reducer.ts
index f496465529..6c00c2d4af 100644
--- a/react/features/base/settings/reducer.ts
+++ b/react/features/base/settings/reducer.ts
@@ -52,18 +52,18 @@ const DEFAULT_STATE: ISettingsState = {
 
 export interface ISettingsState {
     audioOutputDeviceId?: string | boolean;
-    avatarURL?: string | boolean;
+    avatarURL?: string;
     cameraDeviceId?: string | boolean;
     disableCallIntegration?: boolean;
     disableCrashReporting?: boolean;
     disableP2P?: boolean;
     disableSelfView?: boolean;
-    displayName?: string | boolean;
-    email?: string | boolean;
+    displayName?: string;
+    email?: string;
     hideShareAudioHelper?: boolean;
     localFlipX?: boolean;
     micDeviceId?: string | boolean;
-    serverURL?: string | boolean;
+    serverURL?: string;
     soundsIncomingMessage?: boolean;
     soundsParticipantJoined?: boolean;
     soundsParticipantKnocking?: boolean;
@@ -73,12 +73,12 @@ export interface ISettingsState {
     startAudioOnly?: boolean;
     startWithAudioMuted?: boolean;
     startWithVideoMuted?: boolean;
-    userSelectedAudioOutputDeviceId?: string | boolean;
-    userSelectedAudioOutputDeviceLabel?: string | boolean;
-    userSelectedCameraDeviceId?: string | boolean;
-    userSelectedCameraDeviceLabel?: string | boolean;
-    userSelectedMicDeviceId?: string | boolean;
-    userSelectedMicDeviceLabel?: string | boolean;
+    userSelectedAudioOutputDeviceId?: string;
+    userSelectedAudioOutputDeviceLabel?: string;
+    userSelectedCameraDeviceId?: string;
+    userSelectedCameraDeviceLabel?: string;
+    userSelectedMicDeviceId?: string;
+    userSelectedMicDeviceLabel?: string;
     userSelectedNotifications?: {
         [key: string]: boolean;
     } | boolean;
@@ -97,6 +97,7 @@ const filterSubtree: ISettingsState = {};
 Object.keys(DEFAULT_STATE).forEach(key => {
     const key1 = key as keyof typeof filterSubtree;
 
+    // @ts-ignore
     filterSubtree[key1] = true;
 });
 
diff --git a/react/features/base/tracks/reducer.ts b/react/features/base/tracks/reducer.ts
index 0b8d5b4ad0..b3d2226203 100644
--- a/react/features/base/tracks/reducer.ts
+++ b/react/features/base/tracks/reducer.ts
@@ -16,7 +16,7 @@ import {
 
 interface ITrack {
     isReceivingData: boolean;
-    jitsiTrack: Object;
+    jitsiTrack: any;
     lastMediaEvent?: string;
     local: boolean;
     mediaType: string;
diff --git a/react/features/base/util/logger.js b/react/features/base/util/logger.ts
similarity index 90%
rename from react/features/base/util/logger.js
rename to react/features/base/util/logger.ts
index 82d31be58e..dc4e5f3b91 100644
--- a/react/features/base/util/logger.js
+++ b/react/features/base/util/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../logging/functions';
 
 export default getLogger('features/base/util');
diff --git a/react/features/base/util/parseURLParams.ts b/react/features/base/util/parseURLParams.ts
index de43b503b5..1289fda15c 100644
--- a/react/features/base/util/parseURLParams.ts
+++ b/react/features/base/util/parseURLParams.ts
@@ -24,7 +24,7 @@ const blacklist = [ '__proto__', 'constructor', 'prototype' ];
 export function parseURLParams(
         url: URL | string,
         dontParse = false,
-        source = 'hash'): Object {
+        source = 'hash') {
     if (typeof url === 'string') {
         // eslint-disable-next-line no-param-reassign
         url = new URL(url);
diff --git a/react/features/base/util/uri.ts b/react/features/base/util/uri.ts
index 02f1fecad7..9fe1846193 100644
--- a/react/features/base/util/uri.ts
+++ b/react/features/base/util/uri.ts
@@ -330,7 +330,7 @@ export function parseStandardURIString(str: string) {
  *     search: string
  * }}
  */
-export function parseURIString(uri?: string) {
+export function parseURIString(uri?: string): any {
     if (typeof uri !== 'string') {
         return undefined;
     }
diff --git a/react/features/filmstrip/components/web/Thumbnail.tsx b/react/features/filmstrip/components/web/Thumbnail.tsx
index 375ccf042f..3fe2793d1a 100644
--- a/react/features/filmstrip/components/web/Thumbnail.tsx
+++ b/react/features/filmstrip/components/web/Thumbnail.tsx
@@ -1276,7 +1276,7 @@ function _mapStateToProps(state: IState, ownProps: any): Object {
 
     const { gifUrl: gifSrc } = getGifForParticipant(state, id);
     const mode = getGifDisplayMode(state);
-    const participantId = isLocal ? getLocalParticipant(state).id : participantID;
+    const participantId = isLocal ? getLocalParticipant(state)?.id : participantID;
 
     return {
         _audioTrack,
diff --git a/react/features/polls/components/AbstractPollAnswer.tsx b/react/features/polls/components/AbstractPollAnswer.tsx
index 99cbfb182a..f48dfd4a13 100644
--- a/react/features/polls/components/AbstractPollAnswer.tsx
+++ b/react/features/polls/components/AbstractPollAnswer.tsx
@@ -50,7 +50,7 @@ const AbstractPollAnswer = (Component: ComponentType<AbstractProps>) => (props:
 
     const poll: Poll = useSelector((state: IState) => state['features/polls'].polls[pollId]);
 
-    const { id: localId } = useSelector(getLocalParticipant);
+    const { id: localId } = useSelector(getLocalParticipant) ?? { id: '' };
 
     const [ checkBoxStates, setCheckBoxState ] = useState(() => {
         if (poll.lastVote !== null) {
diff --git a/react/features/polls/components/native/PollAnswer.tsx b/react/features/polls/components/native/PollAnswer.tsx
index b5b7c3a296..7eaf22cb8a 100644
--- a/react/features/polls/components/native/PollAnswer.tsx
+++ b/react/features/polls/components/native/PollAnswer.tsx
@@ -33,7 +33,7 @@ const PollAnswer = (props: AbstractProps) => {
         <>
             <Text style = { dialogStyles.questionText } >{ poll.question }</Text>
             <Text style = { dialogStyles.questionOwnerText } >{
-                t('polls.by', { name: localParticipant.name })
+                t('polls.by', { name: localParticipant?.name })
             }
             </Text>
             <View style = { chatStyles.answerContent }>
diff --git a/react/features/reactions/components/web/ReactionsMenu.tsx b/react/features/reactions/components/web/ReactionsMenu.tsx
index 06a441505e..c4139dd3ff 100644
--- a/react/features/reactions/components/web/ReactionsMenu.tsx
+++ b/react/features/reactions/components/web/ReactionsMenu.tsx
@@ -5,7 +5,6 @@ import clsx from 'clsx';
 import React, { Component } from 'react';
 import { WithTranslation } from 'react-i18next';
 import { connect } from 'react-redux';
-import { bindActionCreators } from 'redux';
 
 import { createReactionMenuEvent, createToolbarEvent } from '../../../analytics/AnalyticsEvents';
 import { sendAnalytics } from '../../../analytics/functions';
@@ -53,7 +52,7 @@ interface Props extends WithTranslation {
     /**
      * The ID of the local participant.
      */
-    _localParticipantID: String;
+    _localParticipantID?: string;
 
     /**
      * Whether or not the local participant's hand is raised.
@@ -241,7 +240,7 @@ function mapStateToProps(state: IState) {
     const localParticipant = getLocalParticipant(state);
 
     return {
-        _localParticipantID: localParticipant.id,
+        _localParticipantID: localParticipant?.id,
         _isMobile: isMobileBrowser(),
         _isGifEnabled: isGifEnabled(state),
         _isGifMenuVisible: isGifsMenuOpen(state),
@@ -258,10 +257,7 @@ function mapStateToProps(state: IState) {
 function mapDispatchToProps(dispatch: IStore['dispatch']) {
     return {
         dispatch,
-        ...bindActionCreators(
-        {
-            _dockToolbox: dockToolbox
-        }, dispatch)
+        _dockToolbox: (dock: boolean) => dispatch(dockToolbox(dock))
     };
 }
 
diff --git a/react/features/reactions/functions.any.ts b/react/features/reactions/functions.any.ts
index 298117726a..a88cd3c9b7 100644
--- a/react/features/reactions/functions.any.ts
+++ b/react/features/reactions/functions.any.ts
@@ -72,8 +72,8 @@ export async function sendReactionsWebhook(state: IState, reactions: Array<strin
         sessionId: conference.sessionId,
         submitted: Date.now(),
         reactions,
-        participantId: localParticipant.jwtId,
-        participantName: localParticipant.name,
+        participantId: localParticipant?.jwtId,
+        participantName: localParticipant?.name,
         participantJid: jid
     };
 
diff --git a/react/features/reactions/middleware.ts b/react/features/reactions/middleware.ts
index 1ad570ab6c..927a5861fc 100644
--- a/react/features/reactions/middleware.ts
+++ b/react/features/reactions/middleware.ts
@@ -204,7 +204,7 @@ MiddlewareRegistry.register((store: IStore) => (next: Function) => (action: any)
         const { disableReactionsModeration } = state['features/base/config'];
 
         const customActions = [ 'notify.reactionSounds' ];
-        const customFunctions = [ () => dispatch(updateSettings({
+        const customFunctions: Function[] = [ () => dispatch(updateSettings({
             soundsReactions: false
         })) ];
 
diff --git a/react/features/video-menu/components/web/LocalVideoMenuTriggerButton.tsx b/react/features/video-menu/components/web/LocalVideoMenuTriggerButton.tsx
index 2a0cf85bf7..f991ac3189 100644
--- a/react/features/video-menu/components/web/LocalVideoMenuTriggerButton.tsx
+++ b/react/features/video-menu/components/web/LocalVideoMenuTriggerButton.tsx
@@ -303,7 +303,7 @@ function _mapStateToProps(state: IState, ownProps: Partial<Props>) {
         _showLocalVideoFlipButton: !disableLocalVideoFlip && videoTrack?.videoType !== 'desktop',
         _showHideSelfViewButton: showHideSelfViewButton,
         _overflowDrawer: overflowDrawer,
-        _localParticipantId: localParticipant.id,
+        _localParticipantId: localParticipant?.id,
         _showConnectionInfo: showConnectionInfo,
         _showPinToStage: isStageFilmstripAvailable(state)
     };