diff --git a/globals.d.ts b/globals.d.ts
index 89b20d8482..3de71264aa 100644
--- a/globals.d.ts
+++ b/globals.d.ts
@@ -13,8 +13,10 @@ declare global {
     const interfaceConfig: any;
 
     interface Window {
-        config?: IConfig;
+        config: IConfig;
         JITSI_MEET_LITE_SDK?: boolean;
         interfaceConfig?: any;
     }
+
+    const config: IConfig;
 }
diff --git a/react/features/base/conference/reducer.ts b/react/features/base/conference/reducer.ts
index 7443628cfc..81d1788416 100644
--- a/react/features/base/conference/reducer.ts
+++ b/react/features/base/conference/reducer.ts
@@ -49,6 +49,7 @@ export interface IJitsiConference {
     getLocalTracks: Function;
     grantOwner: Function;
     isAVModerationSupported: Function;
+    isCallstatsEnabled: Function;
     isEndConferenceSupported: Function;
     isLobbySupported: Function;
     kickParticipant: Function;
@@ -60,6 +61,7 @@ export interface IJitsiConference {
     replaceTrack: Function;
     sendCommand: Function;
     sendEndpointMessage: Function;
+    sendFeedback: Function;
     sendLobbyMessage: Function;
     sessionId: string;
     setDisplayName: Function;
diff --git a/react/features/base/config/configType.ts b/react/features/base/config/configType.ts
index cc1dc4a284..92e993e5a0 100644
--- a/react/features/base/config/configType.ts
+++ b/react/features/base/config/configType.ts
@@ -115,6 +115,7 @@ export interface IConfig {
     autoKnockLobby?: boolean;
     backgroundAlpha?: number;
     bosh?: string;
+    brandingDataUrl?: string;
     brandingRoomAlias?: string;
     breakoutRooms?: {
         hideAddRoomButton?: boolean;
@@ -342,6 +343,8 @@ export interface IConfig {
     iAmRecorder?: boolean;
     iAmSipGateway?: boolean;
     inviteAppName?: string | null;
+    jaasFeedbackMetadataURL?: string;
+    jaasTokenUrl?: string;
     lastNLimits?: {
         [key: number]: number;
     };
diff --git a/react/features/base/jwt/reducer.ts b/react/features/base/jwt/reducer.ts
index 69cad1e922..d01fca6c4c 100644
--- a/react/features/base/jwt/reducer.ts
+++ b/react/features/base/jwt/reducer.ts
@@ -12,6 +12,7 @@ export interface IJwtState {
     server?: string;
     tenant?: string;
     user?: {
+        id: string;
         name: string;
     };
 }
diff --git a/react/features/base/settings/reducer.ts b/react/features/base/settings/reducer.ts
index c76dc373d9..86d689244c 100644
--- a/react/features/base/settings/reducer.ts
+++ b/react/features/base/settings/reducer.ts
@@ -86,7 +86,7 @@ export interface ISettingsState {
     userSelectedMicDeviceLabel?: string;
     userSelectedNotifications?: {
         [key: string]: boolean;
-    } | boolean;
+    };
     userSelectedSkipPrejoin?: boolean;
     videoSettingsVisible?: boolean;
     visible?: boolean;
diff --git a/react/features/chat/middleware.js b/react/features/chat/middleware.ts
similarity index 84%
rename from react/features/chat/middleware.js
rename to react/features/chat/middleware.ts
index c4df0d58e9..6952d18e88 100644
--- a/react/features/chat/middleware.js
+++ b/react/features/chat/middleware.ts
@@ -1,12 +1,12 @@
-// @flow
-import { type Dispatch } from 'redux';
-
-import { APP_WILL_MOUNT, APP_WILL_UNMOUNT } from '../base/app';
-import {
-    CONFERENCE_JOINED,
-    getCurrentConference
-} from '../base/conference';
-import { openDialog } from '../base/dialog';
+/* eslint-disable lines-around-comment */
+import { AnyAction } from 'redux';
+
+import { IState, IStore } from '../app/types';
+import { APP_WILL_MOUNT, APP_WILL_UNMOUNT } from '../base/app/actionTypes';
+import { CONFERENCE_JOINED } from '../base/conference/actionTypes';
+import { getCurrentConference } from '../base/conference/functions';
+import { IJitsiConference } from '../base/conference/reducer';
+import { openDialog } from '../base/dialog/actions';
 import {
     JitsiConferenceErrors,
     JitsiConferenceEvents
@@ -15,27 +15,28 @@ import {
     getLocalParticipant,
     getParticipantById,
     getParticipantDisplayName
-} from '../base/participants';
-import { MiddlewareRegistry, StateListenerRegistry } from '../base/redux';
-import { playSound, registerSound, unregisterSound } from '../base/sounds';
+} from '../base/participants/functions';
+import MiddlewareRegistry from '../base/redux/MiddlewareRegistry';
+import StateListenerRegistry from '../base/redux/StateListenerRegistry';
+import { playSound, registerSound, unregisterSound } from '../base/sounds/actions';
 import { addGif } from '../gifs/actions';
 import { GIF_PREFIX } from '../gifs/constants';
 import { getGifDisplayMode, isGifMessage } from '../gifs/functions';
-import { NOTIFICATION_TIMEOUT_TYPE, showMessageNotification } from '../notifications';
+import { showMessageNotification } from '../notifications/actions';
+import { NOTIFICATION_TIMEOUT_TYPE } from '../notifications/constants';
 import { resetNbUnreadPollsMessages } from '../polls/actions';
 import { ADD_REACTION_MESSAGE } from '../reactions/actionTypes';
 import { pushReactions } from '../reactions/actions.any';
 import { ENDPOINT_REACTION_NAME } from '../reactions/constants';
 import { getReactionMessageFromBuffer, isReactionsEnabled } from '../reactions/functions.any';
-import { endpointMessageReceived } from '../subtitles';
-import {
-    showToolbox
-} from '../toolbox/actions';
+import { endpointMessageReceived } from '../subtitles/actions.any';
+// @ts-ignore
+import { showToolbox } from '../toolbox/actions';
 
 
 import { ADD_MESSAGE, CLOSE_CHAT, OPEN_CHAT, SEND_MESSAGE, SET_IS_POLL_TAB_FOCUSED } from './actionTypes';
-import { addMessage, clearMessages } from './actions';
-import { closeChat } from './actions.any';
+import { addMessage, clearMessages, closeChat } from './actions.any';
+// @ts-ignore
 import { ChatPrivacyDialog } from './components';
 import {
     INCOMING_MSG_SOUND_ID,
@@ -47,9 +48,6 @@ import {
 import { getUnreadCount } from './functions';
 import { INCOMING_MSG_SOUND_FILE } from './sounds';
 
-declare var APP: Object;
-declare var interfaceConfig : Object;
-
 /**
  * Timeout for when to show the privacy notice after a private message was received.
  *
@@ -167,13 +165,15 @@ MiddlewareRegistry.register(store => next => action => {
     }
 
     case ADD_REACTION_MESSAGE: {
-        _handleReceivedMessage(store, {
-            id: localParticipant.id,
-            message: action.message,
-            privateMessage: false,
-            timestamp: Date.now(),
-            lobbyChat: false
-        }, false, true);
+        if (localParticipant?.id) {
+            _handleReceivedMessage(store, {
+                id: localParticipant.id,
+                message: action.message,
+                privateMessage: false,
+                timestamp: Date.now(),
+                lobbyChat: false
+            }, false, true);
+        }
     }
     }
 
@@ -220,7 +220,7 @@ StateListenerRegistry.register(
  * @private
  * @returns {void}
  */
-function _addChatMsgListener(conference, store) {
+function _addChatMsgListener(conference: IJitsiConference, store: IStore) {
     if (store.getState()['features/base/config'].iAmRecorder) {
         // We don't register anything on web if we are in iAmRecorder mode
         return;
@@ -228,7 +228,7 @@ function _addChatMsgListener(conference, store) {
 
     conference.on(
         JitsiConferenceEvents.MESSAGE_RECEIVED,
-        (id, message, timestamp) => {
+        (id: string, message: string, timestamp: number) => {
             _onConferenceMessageReceived(store, { id,
                 message,
                 timestamp,
@@ -238,7 +238,7 @@ function _addChatMsgListener(conference, store) {
 
     conference.on(
         JitsiConferenceEvents.PRIVATE_MESSAGE_RECEIVED,
-        (id, message, timestamp) => {
+        (id: string, message: string, timestamp: number) => {
             _onConferenceMessageReceived(store, {
                 id,
                 message,
@@ -250,13 +250,14 @@ function _addChatMsgListener(conference, store) {
 
     conference.on(
         JitsiConferenceEvents.ENDPOINT_MESSAGE_RECEIVED,
-        (...args) => {
+        (...args: any) => {
             const state = store.getState();
 
             if (!isReactionsEnabled(state)) {
                 return;
             }
 
+            // @ts-ignore
             store.dispatch(endpointMessageReceived(...args));
 
             if (args && args.length >= 2) {
@@ -277,7 +278,7 @@ function _addChatMsgListener(conference, store) {
         });
 
     conference.on(
-        JitsiConferenceEvents.CONFERENCE_ERROR, (errorType, error) => {
+        JitsiConferenceEvents.CONFERENCE_ERROR, (errorType: string, error: Error) => {
             errorType === JitsiConferenceErrors.CHAT_ERROR && _handleChatError(store, error);
         });
 }
@@ -289,7 +290,8 @@ function _addChatMsgListener(conference, store) {
  * @param {Object} message - The message object.
  * @returns {void}
  */
-function _onConferenceMessageReceived(store, { id, message, timestamp, privateMessage }) {
+function _onConferenceMessageReceived(store: IStore, { id, message, timestamp, privateMessage }: {
+    id: string; message: string; privateMessage: boolean; timestamp: number; }) {
     const isGif = isGifMessage(message);
 
     if (isGif) {
@@ -315,7 +317,7 @@ function _onConferenceMessageReceived(store, { id, message, timestamp, privateMe
  * @param {string} message - The message sent.
  * @returns {void}
  */
-function _handleGifMessageReceived(store, id, message) {
+function _handleGifMessageReceived(store: IStore, id: string, message: string) {
     const url = message.substring(GIF_PREFIX.length, message.length - 1);
 
     store.dispatch(addGif(id, url));
@@ -328,7 +330,7 @@ function _handleGifMessageReceived(store, id, message) {
  * @param  {string} error - The error message.
  * @returns {void}
  */
-function _handleChatError({ dispatch }, error) {
+function _handleChatError({ dispatch }: IStore, error: Error) {
     dispatch(addMessage({
         hasRead: true,
         messageType: MESSAGE_TYPE_ERROR,
@@ -346,7 +348,7 @@ function _handleChatError({ dispatch }, error) {
  * @returns {Function}
  */
 export function handleLobbyMessageReceived(message: string, participantId: string) {
-    return async (dispatch: Dispatch<any>, getState: Function) => {
+    return async (dispatch: IStore['dispatch'], getState: IStore['getState']) => {
         _handleReceivedMessage({ dispatch,
             getState }, { id: participantId,
             message,
@@ -364,11 +366,11 @@ export function handleLobbyMessageReceived(message: string, participantId: strin
  * @param {string} id - The knocking participant id.
  * @returns {string}
  */
-function getLobbyChatDisplayName(state, id) {
+function getLobbyChatDisplayName(state: IState, id: string) {
     const { knockingParticipants } = state['features/lobby'];
     const { lobbyMessageRecipient } = state['features/chat'];
 
-    if (id === lobbyMessageRecipient.id) {
+    if (id === lobbyMessageRecipient?.id) {
         return lobbyMessageRecipient.name;
     }
 
@@ -390,8 +392,9 @@ function getLobbyChatDisplayName(state, id) {
  * @param {boolean} isReaction - Whether or not the message is a reaction message.
  * @returns {void}
  */
-function _handleReceivedMessage({ dispatch, getState },
-        { id, message, privateMessage, timestamp, lobbyChat },
+function _handleReceivedMessage({ dispatch, getState }: IStore,
+        { id, message, privateMessage, timestamp, lobbyChat }: {
+        id: string; lobbyChat: boolean; message: string; privateMessage: boolean; timestamp: number; },
         shouldPlaySound = true,
         isReaction = false
 ) {
@@ -407,7 +410,7 @@ function _handleReceivedMessage({ dispatch, getState },
 
     // Provide a default for for the case when a message is being
     // backfilled for a participant that has left the conference.
-    const participant = getParticipantById(state, id) || {};
+    const participant = getParticipantById(state, id) || { local: undefined };
 
     const localParticipant = getLocalParticipant(getState);
     const displayName = lobbyChat
@@ -418,7 +421,7 @@ function _handleReceivedMessage({ dispatch, getState },
     const millisecondsTimestamp = timestampToDate.getTime();
 
     // skip message notifications on join (the messages having timestamp - coming from the history)
-    const shouldShowNotification = userSelectedNotifications['notify.chatMessages']
+    const shouldShowNotification = userSelectedNotifications?.['notify.chatMessages']
         && !hasRead && !isReaction && !timestamp;
 
     dispatch(addMessage({
@@ -429,7 +432,7 @@ function _handleReceivedMessage({ dispatch, getState },
         message,
         privateMessage,
         lobbyChat,
-        recipient: getParticipantDisplayName(state, localParticipant.id),
+        recipient: getParticipantDisplayName(state, localParticipant?.id ?? ''),
         timestamp: millisecondsTimestamp,
         isReaction
     }));
@@ -471,9 +474,14 @@ function _handleReceivedMessage({ dispatch, getState },
  * @param {boolean} isLobbyPrivateMessage - Is a lobby message.
  * @returns {void}
  */
-function _persistSentPrivateMessage({ dispatch, getState }, recipientID, message, isLobbyPrivateMessage = false) {
+function _persistSentPrivateMessage({ dispatch, getState }: IStore, recipientID: string,
+        message: string, isLobbyPrivateMessage = false) {
     const state = getState();
     const localParticipant = getLocalParticipant(state);
+
+    if (!localParticipant?.id) {
+        return;
+    }
     const displayName = getParticipantDisplayName(state, localParticipant.id);
     const { lobbyMessageRecipient } = state['features/chat'];
 
@@ -486,7 +494,7 @@ function _persistSentPrivateMessage({ dispatch, getState }, recipientID, message
         privateMessage: !isLobbyPrivateMessage,
         lobbyChat: isLobbyPrivateMessage,
         recipient: isLobbyPrivateMessage
-            ? lobbyMessageRecipient && lobbyMessageRecipient.name
+            ? lobbyMessageRecipient?.name
             : getParticipantDisplayName(getState, recipientID),
         timestamp: Date.now()
     }));
@@ -500,7 +508,7 @@ function _persistSentPrivateMessage({ dispatch, getState }, recipientID, message
  * @param {Object} action - The action being dispatched now.
  * @returns {string?}
  */
-function _shouldSendPrivateMessageTo(state, action): ?string {
+function _shouldSendPrivateMessageTo(state: IState, action: AnyAction) {
     if (action.ignorePrivacy) {
         // Shortcut: this is only true, if we already displayed the notice, so no need to show it again.
         return undefined;
diff --git a/react/features/chat/reducer.ts b/react/features/chat/reducer.ts
index 9c5bc5bac4..f0fc47e188 100644
--- a/react/features/chat/reducer.ts
+++ b/react/features/chat/reducer.ts
@@ -38,7 +38,7 @@ export interface IMessage {
     messageType: string;
     privateMessage: boolean;
     recipient: string;
-    timestamp: string;
+    timestamp: number;
 }
 
 export interface IChatState {
diff --git a/react/features/display-name/actions.js b/react/features/display-name/actions.ts
similarity index 72%
rename from react/features/display-name/actions.js
rename to react/features/display-name/actions.ts
index 771a2be6ac..ff4ce2b1cd 100644
--- a/react/features/display-name/actions.js
+++ b/react/features/display-name/actions.ts
@@ -1,7 +1,6 @@
-// @flow
-
-import { openDialog } from '../../features/base/dialog';
+import { openDialog } from '../base/dialog/actions';
 
+// @ts-ignore
 import { DisplayNamePrompt } from './components';
 
 /**
@@ -11,7 +10,7 @@ import { DisplayNamePrompt } from './components';
  * submit of the dialog.
  * @returns {Object}
  */
-export function openDisplayNamePrompt(onPostSubmit: ?Function) {
+export function openDisplayNamePrompt(onPostSubmit?: Function) {
     return openDialog(DisplayNamePrompt, {
         onPostSubmit
     });
diff --git a/react/features/display-name/middleware.js b/react/features/display-name/middleware.ts
similarity index 67%
rename from react/features/display-name/middleware.js
rename to react/features/display-name/middleware.ts
index 163cc1f335..8a5455d1bb 100644
--- a/react/features/display-name/middleware.js
+++ b/react/features/display-name/middleware.ts
@@ -1,9 +1,9 @@
-// @flow
-
-import { hideDialog, isDialogOpen } from '../base/dialog';
-import { MiddlewareRegistry } from '../base/redux';
-import { SETTINGS_UPDATED } from '../base/settings';
+import { hideDialog } from '../base/dialog/actions';
+import { isDialogOpen } from '../base/dialog/functions';
+import MiddlewareRegistry from '../base/redux/MiddlewareRegistry';
+import { SETTINGS_UPDATED } from '../base/settings/actionTypes';
 
+// @ts-ignore
 import { DisplayNamePrompt } from './components';
 
 /**
diff --git a/react/features/dynamic-branding/functions.any.js b/react/features/dynamic-branding/functions.any.ts
similarity index 79%
rename from react/features/dynamic-branding/functions.any.js
rename to react/features/dynamic-branding/functions.any.ts
index 26cc80b537..73bf3b8bca 100644
--- a/react/features/dynamic-branding/functions.any.js
+++ b/react/features/dynamic-branding/functions.any.ts
@@ -1,6 +1,6 @@
-// @flow
-
-import { toState } from '../base/redux';
+import { IState } from '../app/types';
+import { IStateful } from '../base/app/types';
+import { toState } from '../base/redux/functions';
 
 
 /**
@@ -10,13 +10,13 @@ import { toState } from '../base/redux';
  * @param {Object} state - A redux state.
  * @returns {string}
  */
-export function extractFqnFromPath(state?: Object) {
+export function extractFqnFromPath(state?: IState) {
     let pathname;
 
     if (window.location.pathname) {
         pathname = window.location.pathname;
-    } else if (state && state['features/base/connection']) {
-        pathname = state['features/base/connection'].locationURL.pathname;
+    } else if (state?.['features/base/connection']) {
+        pathname = state['features/base/connection'].locationURL?.pathname ?? '';
     } else {
         return '';
     }
@@ -34,7 +34,7 @@ export function extractFqnFromPath(state?: Object) {
  * {@code getState} function.
  * @returns {string}
  */
-export async function getDynamicBrandingUrl(stateful: Object | Function) {
+export async function getDynamicBrandingUrl(stateful: IStateful) {
     const state = toState(stateful);
 
     // NB: On web this is dispatched really early, before the config has been stored in the
@@ -61,6 +61,6 @@ export async function getDynamicBrandingUrl(stateful: Object | Function) {
  * @param {Object} state - Global state of the app.
  * @returns {boolean}
  */
-export function isDynamicBrandingDataLoaded(state: Object) {
+export function isDynamicBrandingDataLoaded(state: IState) {
     return state['features/dynamic-branding'].customizationReady;
 }
diff --git a/react/features/e2ee/functions.js b/react/features/e2ee/functions.ts
similarity index 82%
rename from react/features/e2ee/functions.js
rename to react/features/e2ee/functions.ts
index 1257733fc6..495171a319 100644
--- a/react/features/e2ee/functions.js
+++ b/react/features/e2ee/functions.ts
@@ -1,6 +1,6 @@
-
+import { IStateful } from '../base/app/types';
 import { getParticipantCount } from '../base/participants/functions';
-import { toState } from '../base/redux';
+import { toState } from '../base/redux/functions';
 
 import { MAX_MODE_LIMIT, MAX_MODE_THRESHOLD } from './constants';
 
@@ -8,14 +8,14 @@ import { MAX_MODE_LIMIT, MAX_MODE_THRESHOLD } from './constants';
  * Gets the value of a specific React {@code Component} prop of the currently
  * mounted {@link App}.
  *
- * @param {Function|Object} stateful - The redux store or {@code getState}
+ * @param {IStateful} stateful - The redux store or {@code getState}
  * function.
  * @param {string} propName - The name of the React {@code Component} prop of
  * the currently mounted {@code App} to get.
  * @returns {*} The value of the specified React {@code Component} prop of the
  * currently mounted {@code App}.
  */
-export function doesEveryoneSupportE2EE(stateful) {
+export function doesEveryoneSupportE2EE(stateful: IStateful) {
     const state = toState(stateful);
     const { everyoneSupportE2EE } = state['features/e2ee'];
     const { e2eeSupported } = state['features/base/conference'];
@@ -37,7 +37,7 @@ export function doesEveryoneSupportE2EE(stateful) {
  * function.
  * @returns {boolean}.
  */
-export function isMaxModeReached(stateful) {
+export function isMaxModeReached(stateful: IStateful) {
     const participantCount = getParticipantCount(toState(stateful));
 
     return participantCount >= MAX_MODE_LIMIT;
@@ -50,7 +50,7 @@ export function isMaxModeReached(stateful) {
  * function.
  * @returns {boolean}.
  */
-export function isMaxModeThresholdReached(stateful) {
+export function isMaxModeThresholdReached(stateful: IStateful) {
     const participantCount = getParticipantCount(toState(stateful));
 
     return participantCount >= MAX_MODE_LIMIT + MAX_MODE_THRESHOLD;
diff --git a/react/features/e2ee/logger.js b/react/features/e2ee/logger.ts
similarity index 90%
rename from react/features/e2ee/logger.js
rename to react/features/e2ee/logger.ts
index ef2342ebd4..cdad6b5194 100644
--- a/react/features/e2ee/logger.js
+++ b/react/features/e2ee/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../base/logging/functions';
 
 export default getLogger('features/e2ee');
diff --git a/react/features/e2ee/middleware.js b/react/features/e2ee/middleware.ts
similarity index 88%
rename from react/features/e2ee/middleware.js
rename to react/features/e2ee/middleware.ts
index bd029c8020..383a513545 100644
--- a/react/features/e2ee/middleware.js
+++ b/react/features/e2ee/middleware.ts
@@ -1,22 +1,21 @@
-// @flow
-
 import { batch } from 'react-redux';
 
-import { APP_WILL_MOUNT, APP_WILL_UNMOUNT } from '../base/app';
-import { CONFERENCE_JOINED, getCurrentConference } from '../base/conference';
+import { IStore } from '../app/types';
+import { APP_WILL_MOUNT, APP_WILL_UNMOUNT } from '../base/app/actionTypes';
+import { CONFERENCE_JOINED } from '../base/conference/actionTypes';
+import { getCurrentConference } from '../base/conference/functions';
+import { PARTICIPANT_JOINED, PARTICIPANT_LEFT, PARTICIPANT_UPDATED } from '../base/participants/actionTypes';
+import { participantUpdated } from '../base/participants/actions';
 import {
-    PARTICIPANT_JOINED,
-    PARTICIPANT_LEFT,
-    PARTICIPANT_UPDATED,
     getLocalParticipant,
     getParticipantById,
     getParticipantCount,
     getRemoteParticipants,
-    isScreenShareParticipant,
-    participantUpdated
-} from '../base/participants';
-import { MiddlewareRegistry, StateListenerRegistry } from '../base/redux';
-import { playSound, registerSound, unregisterSound } from '../base/sounds';
+    isScreenShareParticipant
+} from '../base/participants/functions';
+import MiddlewareRegistry from '../base/redux/MiddlewareRegistry';
+import StateListenerRegistry from '../base/redux/StateListenerRegistry';
+import { playSound, registerSound, unregisterSound } from '../base/sounds/actions';
 
 import { SET_MEDIA_ENCRYPTION_KEY, TOGGLE_E2EE } from './actionTypes';
 import { setE2EEMaxMode, setEveryoneEnabledE2EE, setEveryoneSupportE2EE, toggleE2EE } from './actions';
@@ -66,7 +65,7 @@ MiddlewareRegistry.register(({ dispatch, getState }) => next => action => {
             let newEveryoneSupportE2EE = true;
             let newEveryoneEnabledE2EE = true;
 
-            // eslint-disable-next-line no-unused-vars
+            // eslint-disable-next-line @typescript-eslint/no-unused-vars
             for (const [ key, p ] of getRemoteParticipants(state)) {
                 if (!p.e2eeEnabled) {
                     newEveryoneEnabledE2EE = false;
@@ -136,10 +135,10 @@ MiddlewareRegistry.register(({ dispatch, getState }) => next => action => {
 
     case PARTICIPANT_LEFT: {
         const previosState = getState();
-        const participant = getParticipantById(previosState, action.participant?.id) || {};
+        const participant = getParticipantById(previosState, action.participant?.id);
         const result = next(action);
         const newState = getState();
-        const { e2eeEnabled = false, e2eeSupported = false } = participant;
+        const { e2eeEnabled = false, e2eeSupported = false } = participant ?? {};
 
         if (isScreenShareParticipant(participant)) {
             return result;
@@ -154,7 +153,7 @@ MiddlewareRegistry.register(({ dispatch, getState }) => next => action => {
             let latestEveryoneEnabledE2EE = true;
             let latestEveryoneSupportE2EE = true;
 
-            // eslint-disable-next-line no-unused-vars
+            // eslint-disable-next-line @typescript-eslint/no-unused-vars
             for (const [ key, p ] of getRemoteParticipants(newState)) {
                 if (!p.e2eeEnabled) {
                     latestEveryoneEnabledE2EE = false;
@@ -190,7 +189,7 @@ MiddlewareRegistry.register(({ dispatch, getState }) => next => action => {
     }
 
     case TOGGLE_E2EE: {
-        if (conference && conference.isE2EESupported() && conference.isE2EEEnabled() !== action.enabled) {
+        if (conference?.isE2EESupported() && conference.isE2EEEnabled() !== action.enabled) {
             logger.debug(`E2EE will be ${action.enabled ? 'enabled' : 'disabled'}`);
             conference.toggleE2EE(action.enabled);
 
@@ -199,7 +198,7 @@ MiddlewareRegistry.register(({ dispatch, getState }) => next => action => {
 
             dispatch(participantUpdated({
                 e2eeEnabled: action.enabled,
-                id: participant.id,
+                id: participant?.id ?? '',
                 local: true
             }));
 
@@ -212,7 +211,7 @@ MiddlewareRegistry.register(({ dispatch, getState }) => next => action => {
     }
 
     case SET_MEDIA_ENCRYPTION_KEY: {
-        if (conference && conference.isE2EESupported()) {
+        if (conference?.isE2EESupported()) {
             const { exportedKey, index } = action.keyInfo;
 
             if (exportedKey) {
@@ -265,7 +264,7 @@ StateListenerRegistry.register(
  * @private
  * @returns {void}
  */
-function _updateMaxMode(dispatch, getState) {
+function _updateMaxMode(dispatch: IStore['dispatch'], getState: IStore['getState']) {
     const state = getState();
 
     const { e2ee = {} } = state['features/base/config'];
diff --git a/react/features/e2ee/sounds.js b/react/features/e2ee/sounds.ts
similarity index 96%
rename from react/features/e2ee/sounds.js
rename to react/features/e2ee/sounds.ts
index e349d62d46..1519b4db95 100644
--- a/react/features/e2ee/sounds.js
+++ b/react/features/e2ee/sounds.ts
@@ -1,5 +1,3 @@
-// @flow
-
 /**
  * The name of the bundled audio file which will be played when e2ee is disabled.
  *
diff --git a/react/features/feedback/actions.js b/react/features/feedback/actions.ts
similarity index 86%
rename from react/features/feedback/actions.js
rename to react/features/feedback/actions.ts
index 688a6d4e97..ad5606b9b2 100644
--- a/react/features/feedback/actions.js
+++ b/react/features/feedback/actions.ts
@@ -1,9 +1,8 @@
-// @flow
-
-import type { Dispatch } from 'redux';
-
+// @ts-ignore
 import { FEEDBACK_REQUEST_IN_PROGRESS } from '../../../modules/UI/UIErrors';
-import { openDialog } from '../base/dialog';
+import { IStore } from '../app/types';
+import { IJitsiConference } from '../base/conference/reducer';
+import { openDialog } from '../base/dialog/actions';
 import { extractFqnFromPath } from '../dynamic-branding/functions.any';
 import { isVpaasMeeting } from '../jaas/functions';
 
@@ -12,11 +11,11 @@ import {
     SUBMIT_FEEDBACK_ERROR,
     SUBMIT_FEEDBACK_SUCCESS
 } from './actionTypes';
+// eslint-disable-next-line lines-around-comment
+// @ts-ignore
 import { FeedbackDialog } from './components';
 import { sendFeedbackToJaaSRequest } from './functions';
 
-declare var config: Object;
-
 /**
  * Caches the passed in feedback in the redux store.
  *
@@ -48,13 +47,13 @@ export function cancelFeedback(score: number, message: string) {
  * resolved with true if the dialog is disabled or the feedback was already
  * submitted. Rejected if another dialog is already displayed.
  */
-export function maybeOpenFeedbackDialog(conference: Object) {
+export function maybeOpenFeedbackDialog(conference: IJitsiConference) {
     type R = {
-        feedbackSubmitted: boolean,
-        showThankYou: boolean
+        feedbackSubmitted: boolean;
+        showThankYou: boolean;
     };
 
-    return (dispatch: Dispatch<any>, getState: Function): Promise<R> => {
+    return (dispatch: IStore['dispatch'], getState: IStore['getState']): Promise<R> => {
         const state = getState();
         const { feedbackPercentage = 100 } = state['features/base/config'];
 
@@ -105,7 +104,7 @@ export function maybeOpenFeedbackDialog(conference: Object) {
  * is closed.
  * @returns {Object}
  */
-export function openFeedbackDialog(conference: Object, onClose: ?Function) {
+export function openFeedbackDialog(conference: Object, onClose?: Function) {
     return openDialog(FeedbackDialog, {
         conference,
         onClose
@@ -120,8 +119,8 @@ export function openFeedbackDialog(conference: Object, onClose: ?Function) {
  *
  * @returns {Promise}
  */
-export function sendJaasFeedbackMetadata(conference: Object, feedback: Object) {
-    return (dispatch: Dispatch<any>, getState: Function): Promise<any> => {
+export function sendJaasFeedbackMetadata(conference: IJitsiConference, feedback: Object) {
+    return (dispatch: IStore['dispatch'], getState: IStore['getState']): Promise<any> => {
         const state = getState();
         const { jaasFeedbackMetadataURL } = state['features/base/config'];
 
@@ -135,7 +134,7 @@ export function sendJaasFeedbackMetadata(conference: Object, feedback: Object) {
         const feedbackData = {
             ...feedback,
             sessionId: conference.sessionId,
-            userId: user.id,
+            userId: user?.id,
             meetingFqn,
             jwt,
             tenant
@@ -159,8 +158,8 @@ export function sendJaasFeedbackMetadata(conference: Object, feedback: Object) {
 export function submitFeedback(
         score: number,
         message: string,
-        conference: Object) {
-    return (dispatch: Dispatch<any>) =>
+        conference: IJitsiConference) {
+    return (dispatch: IStore['dispatch']) =>
         conference.sendFeedback(score, message)
         .then(() => dispatch({ type: SUBMIT_FEEDBACK_SUCCESS }))
         .then(() => dispatch(sendJaasFeedbackMetadata(conference, { score,
diff --git a/react/features/feedback/functions.js b/react/features/feedback/functions.ts
similarity index 87%
rename from react/features/feedback/functions.js
rename to react/features/feedback/functions.ts
index bdc14ae50e..47963c71b4 100644
--- a/react/features/feedback/functions.js
+++ b/react/features/feedback/functions.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import logger from './logger';
 
 /**
@@ -9,7 +7,10 @@ import logger from './logger';
  * @param {Object} feedbackData - The feedback data object.
  * @returns {Promise}
  */
-export async function sendFeedbackToJaaSRequest(url: string, feedbackData: Object) {
+export async function sendFeedbackToJaaSRequest(url: string, feedbackData: {
+    jwt?: string; meetingFqn: string; message?: string; score?: number;
+    sessionId: string; tenant?: string; userId?: string;
+}) {
     const {
         jwt,
         sessionId,
diff --git a/react/features/feedback/logger.js b/react/features/feedback/logger.ts
similarity index 91%
rename from react/features/feedback/logger.js
rename to react/features/feedback/logger.ts
index 9ab94be315..7ba2e68455 100644
--- a/react/features/feedback/logger.js
+++ b/react/features/feedback/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../base/logging/functions';
 
 export default getLogger('features/feedback');
diff --git a/react/features/jaas/functions.js b/react/features/jaas/functions.ts
similarity index 81%
rename from react/features/jaas/functions.js
rename to react/features/jaas/functions.ts
index ba7cc79aab..447366cdf9 100644
--- a/react/features/jaas/functions.js
+++ b/react/features/jaas/functions.ts
@@ -1,5 +1,4 @@
-// @flow
-
+import { IState } from '../app/types';
 
 import { VPAAS_TENANT_PREFIX } from './constants';
 import logger from './logger';
@@ -23,20 +22,20 @@ function extractVpaasTenantFromPath(path: string) {
 /**
  * Returns the vpaas tenant.
  *
- * @param {Object} state - The global state.
+ * @param {IState} state - The global state.
  * @returns {string}
  */
-export function getVpaasTenant(state: Object) {
-    return extractVpaasTenantFromPath(state['features/base/connection'].locationURL.pathname);
+export function getVpaasTenant(state: IState) {
+    return extractVpaasTenantFromPath(state['features/base/connection'].locationURL?.pathname ?? '');
 }
 
 /**
  * Returns true if the current meeting is a vpaas one.
  *
- * @param {Object} state - The state of the app.
+ * @param {IState} state - The state of the app.
  * @returns {boolean}
  */
-export function isVpaasMeeting(state: Object) {
+export function isVpaasMeeting(state: IState) {
     const connection = state['features/base/connection'];
 
     if (connection?.locationURL?.pathname) {
@@ -57,8 +56,8 @@ export function isVpaasMeeting(state: Object) {
  * @returns {void}
  */
 export async function sendGetDetailsRequest({ appId, baseUrl }: {
-    appId: string,
-    baseUrl: string,
+    appId: string;
+    baseUrl: string;
 }) {
     const fullUrl = `${baseUrl}/v1/public/tenants/${encodeURIComponent(appId)}`;
 
@@ -70,7 +69,7 @@ export async function sendGetDetailsRequest({ appId, baseUrl }: {
         }
 
         throw new Error('Request not successful');
-    } catch (err) {
+    } catch (err: any) {
         throw new Error(err);
 
     }
@@ -79,11 +78,11 @@ export async function sendGetDetailsRequest({ appId, baseUrl }: {
 /**
  * Returns the billing id for vpaas meetings.
  *
- * @param {Object} state - The state of the app.
+ * @param {IState} state - The state of the app.
  * @param {string} feature - Feature to be looked up for disable state.
  * @returns {boolean}
  */
-export function isFeatureDisabled(state: Object, feature: string) {
+export function isFeatureDisabled(state: IState, feature: string) {
     return state['features/jaas'].disabledFeatures.includes(feature);
 }
 
@@ -96,8 +95,8 @@ export function isFeatureDisabled(state: Object, feature: string) {
  * @returns {void}
  */
 export async function sendGetJWTRequest({ appId, baseUrl }: {
-    appId: string,
-    baseUrl: string
+    appId: string;
+    baseUrl: string;
 }) {
     const fullUrl = `${baseUrl}/v1/public/token/${encodeURIComponent(appId)}`;
 
@@ -111,7 +110,7 @@ export async function sendGetJWTRequest({ appId, baseUrl }: {
         }
 
         throw new Error('Request not successful');
-    } catch (err) {
+    } catch (err: any) {
         throw new Error(err);
 
     }
@@ -120,10 +119,10 @@ export async function sendGetJWTRequest({ appId, baseUrl }: {
 /**
  * Gets a jaas JWT.
  *
- * @param {Object} state - Redux state.
+ * @param {IState} state - Redux state.
  * @returns {string} The JWT.
  */
-export async function getJaasJWT(state: Object) {
+export async function getJaasJWT(state: IState) {
     const baseUrl = state['features/base/config'].jaasTokenUrl;
     const appId = getVpaasTenant(state);
 
@@ -133,7 +132,7 @@ export async function getJaasJWT(state: Object) {
         try {
             const jwt = await sendGetJWTRequest({
                 appId,
-                baseUrl
+                baseUrl: baseUrl ?? ''
             });
 
             return jwt.token;
diff --git a/react/features/jaas/logger.js b/react/features/jaas/logger.ts
similarity index 90%
rename from react/features/jaas/logger.js
rename to react/features/jaas/logger.ts
index 725fa328d0..c8f5fb0700 100644
--- a/react/features/jaas/logger.js
+++ b/react/features/jaas/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../base/logging/functions';
 
 export default getLogger('features/jaas');
diff --git a/react/features/subtitles/actions.any.js b/react/features/subtitles/actions.any.ts
similarity index 97%
rename from react/features/subtitles/actions.any.js
rename to react/features/subtitles/actions.any.ts
index 221de7ac4d..9f20e417be 100644
--- a/react/features/subtitles/actions.any.js
+++ b/react/features/subtitles/actions.any.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import {
     ENDPOINT_MESSAGE_RECEIVED,
     REMOVE_TRANSCRIPT_MESSAGE,
@@ -102,7 +100,7 @@ export function setRequestingSubtitles(enabled: boolean) {
  *      type: UPDATE_TRANSLATION_LANGUAGE
  * }}
  */
-export function updateTranslationLanguage(value) {
+export function updateTranslationLanguage(value: boolean) {
     return {
         type: UPDATE_TRANSLATION_LANGUAGE,
         value