diff --git a/main/document/upload.php b/main/document/upload.php
index b37144f4f7..4269d90cbf 100755
--- a/main/document/upload.php
+++ b/main/document/upload.php
@@ -204,7 +204,6 @@ $(function () {
 
 </script>";
 
-
 // This needs cleaning!
 if (!empty($groupId)) {
     // If the group id is set, check if the user has the right to be here
diff --git a/main/dropbox/dropbox_functions.inc.php b/main/dropbox/dropbox_functions.inc.php
index 8fd01619cf..4944bd0404 100755
--- a/main/dropbox/dropbox_functions.inc.php
+++ b/main/dropbox/dropbox_functions.inc.php
@@ -222,9 +222,9 @@ function store_move($id, $target, $part)
     $dropbox_cnf = getDropboxConf();
     $course_id = api_get_course_int_id();
 
-    if ((isset($id) AND $id != '') AND
-        (isset($target) AND $target != '') AND
-        (isset($part) AND $part != '')
+    if ((isset($id) && $id != '') &&
+        (isset($target) && $target != '') &&
+        (isset($part) && $part != '')
     ) {
 
         if ($part == 'received') {
@@ -469,7 +469,7 @@ function display_addcategory_form($category_name = '', $id = '', $action)
     $course_id = api_get_course_int_id();
     $title = get_lang('AddNewCategory');
 
-    if (isset($id) AND $id != '') {
+    if (isset($id) && $id != '') {
         // retrieve the category we are editing
         $sql = "SELECT * FROM ".$dropbox_cnf['tbl_category']."
                 WHERE c_id = $course_id AND cat_id = ".intval($id)."";
@@ -693,7 +693,53 @@ function display_add_form($dropbox_unid, $viewReceivedCategory, $viewSentCategor
         )
     );
     $form->addButtonUpload(get_lang('Upload'), 'submitWork');
-    $form->display();
+
+
+    $headers = array(
+        get_lang('Upload'),
+        get_lang('Upload').' ('.get_lang('Simple').')',
+    );
+
+    $multipleForm = new FormValidator(
+        'sent_multiple',
+        'post',
+        '#',
+        null,
+        array('enctype' => 'multipart/form-data', 'id' => 'fileupload')
+    );
+
+    $multipleForm->addSelect(
+        'recipients',
+        get_lang('SendTo'),
+        $options,
+        array(
+            'multiple' => 'multiple',
+            'size' => '10',
+            'id' => 'recipient_form'
+        )
+    );
+
+    $multipleForm->addHtml('
+        <div id="multiple_form" style="display:none">
+        <div class="description-upload">'.get_lang('ClickToSelectOrDragAndDropMultipleFilesOnTheUploadField').'</div>
+            <span class="btn btn-success fileinput-button">
+                <i class="glyphicon glyphicon-plus"></i>
+                <span>'.get_lang('AddFiles').'</span>
+                <!-- The file input field used as target for the file upload widget -->
+                <input id="input_fileupload" type="file" name="files[]" multiple>
+            </span>
+
+            <br />
+            <br />
+            <!-- The global progress bar -->
+            <div id="progress" class="progress">
+                <div class="progress-bar progress-bar-success"></div>
+            </div>
+            <div id="files" class="files"></div>
+        </div>
+    ');
+
+    echo Display::tabs($headers, array($multipleForm->returnForm(), $form->returnForm()), 'tabs');
 }
 
 /**
@@ -863,14 +909,20 @@ function dropbox_cnf($variable)
 }
 
 /**
+ * @param array $file
+ *
  * @return array|null|string
  */
-function store_add_dropbox()
+function store_add_dropbox($file = [])
 {
     $_course = api_get_course_info();
     $_user = api_get_user_info();
     $dropbox_cnf = getDropboxConf();
 
+    if (empty($file)) {
+        $file = isset($_FILES['file']) ? $_FILES['file'] : null;
+    }
+
     // Validating the form data
 
     // there are no recipients selected
@@ -886,28 +938,34 @@ function store_add_dropbox()
             } elseif ($rec == 'upload') {
                 $thisIsJustUpload = true;
             } elseif (strpos($rec, 'user_') === 0 && !isCourseMember(substr($rec, strlen('user_')))) {
-                return get_lang('InvalideUserDetected');
+                Display::addFlash(Display::return_message(get_lang('InvalideUserDetected'), 'warning'));
+                return false;
             } elseif (strpos($rec, 'group_') !== 0 && strpos($rec, 'user_') !== 0) {
-                return get_lang('InvalideGroupDetected');
+                Display::addFlash(Display::return_message(get_lang('InvalideGroupDetected'), 'warning'));
+                return false;
             }
         }
     }
 
     // we are doing a mailing but an additional recipient is selected
     if ($thisIsAMailing && (count($_POST['recipients']) != 1)) {
-        return get_lang('MailingSelectNoOther');
+        Display::addFlash(Display::return_message(get_lang('MailingSelectNoOther'), 'warning'));
+
+        return false;
     }
 
     // we are doing a just upload but an additional recipient is selected.
     // note: why can't this be valid? It is like sending a document to
     // yourself AND to a different person (I do this quite often with my e-mails)
     if ($thisIsJustUpload && (count($_POST['recipients']) != 1)) {
-        return get_lang('MailingJustUploadSelectNoOther');
+
+        Display::addFlash(Display::return_message(get_lang('MailingJustUploadSelectNoOther'), 'warning'));
+        return false;
     }
 
-    if (empty($_FILES['file']['name'])) {
-        $error = true;
-        return get_lang('NoFileSpecified');
+    if (empty($file['name'])) {
+        Display::addFlash(Display::return_message(get_lang('NoFileSpecified'), 'warning'));
+        return false;
     }
 
     // are we overwriting a previous file or sending a new one
@@ -919,23 +977,26 @@ function store_add_dropbox()
 
     // doing the upload
 
-    $dropbox_filename = $_FILES['file']['name'];
-    $dropbox_filesize = $_FILES['file']['size'];
-    $dropbox_filetype = $_FILES['file']['type'];
-    $dropbox_filetmpname = $_FILES['file']['tmp_name'];
+    $dropbox_filename = $file['name'];
+    $dropbox_filesize = $file['size'];
+    $dropbox_filetype = $file['type'];
+    $dropbox_filetmpname = $file['tmp_name'];
 
     // check if the filesize does not exceed the allowed size.
     if ($dropbox_filesize <= 0 || $dropbox_filesize > $dropbox_cnf['maxFilesize']) {
-        return get_lang('DropboxFileTooBig');
-        // TODO: The "too big" message does not fit in the case of uploading zero-sized file.
+        Display::addFlash(Display::return_message(get_lang('DropboxFileTooBig'), 'warning'));
+
+        return false;
     }
 
     // check if the file is actually uploaded
     if (!is_uploaded_file($dropbox_filetmpname)) { // check user fraud : no clean error msg.
-        return get_lang('TheFileIsNotUploaded');
+        Display::addFlash(Display::return_message(get_lang('TheFileIsNotUploaded'), 'warning'));
+
+        return false;
     }
 
-    $upload_ok = process_uploaded_file($_FILES['file'], true);
+    $upload_ok = process_uploaded_file($file, true);
 
     if (!$upload_ok) {
         return null;
@@ -950,7 +1011,8 @@ function store_add_dropbox()
 
     //filter extension
     if (!filter_extension($dropbox_filename)) {
-        return get_lang('UplUnableToSaveFileFilteredExtension');
+        Display::addFlash(Display::return_message(get_lang('UplUnableToSaveFileFilteredExtension'), 'warning'));
+        return false;
     }
 
     // set title
@@ -973,10 +1035,13 @@ function store_add_dropbox()
         foreach ($dropbox_person->sentWork as $w) {
             if ($w->title == $dropbox_filename) {
                 if (($w->recipients[0]['id'] > dropbox_cnf('mailingIdBase')) xor $thisIsAMailing) {
-                    return get_lang('MailingNonMailingError');
+                    Display::addFlash(Display::return_message(get_lang('MailingNonMailingError'), 'warning'));
+                    return false;
                 }
                 if (($w->recipients[0]['id'] == $_user['user_id']) xor $thisIsJustUpload) {
-                    return get_lang('MailingJustUploadSelectNoOther');
+
+                    Display::addFlash(Display::return_message(get_lang('MailingJustUploadSelectNoOther'), 'warning'));
+                    return false;
                 }
                 $dropbox_filename = $w->filename;
                 $found = true; // note: do we still need this?
@@ -1046,7 +1111,7 @@ function store_add_dropbox()
         }
     }
 
-    new Dropbox_SentWork(
+    $result = new Dropbox_SentWork(
         $_user['user_id'],
         $dropbox_title,
         isset($_POST['description']) ? $_POST['description'] : '',
@@ -1057,11 +1122,13 @@ function store_add_dropbox()
     );
 
     Security::clear_token();
-    return get_lang('FileUploadSucces');
+    Display::addFlash(Display::return_message(get_lang('FileUploadSucces')));
+
+    return $result;
 }
 
 /**
-* this function transforms the array containing all the feedback into something visually attractive.
+* Transforms the array containing all the feedback into something visually attractive.
 *
 * @param an array containing all the feedback about the given message.
 *
diff --git a/main/dropbox/dropbox_init.inc.php b/main/dropbox/dropbox_init.inc.php
index c3bd9fefb6..820bb2850b 100755
--- a/main/dropbox/dropbox_init.inc.php
+++ b/main/dropbox/dropbox_init.inc.php
@@ -113,15 +113,10 @@ Version 1.4 (Yannick Warnier)
  * @package chamilo.dropbox
  */
 
-/**
- * Code
- */
-/*	INIT SECTION */
-
 use ChamiloSession as Session;
 
 // including the basic Chamilo initialisation file
-require_once '../inc/global.inc.php';
+require_once __DIR__.'/../inc/global.inc.php';
 $is_allowed_in_course = api_is_allowed_in_course();
 $is_courseTutor = api_is_course_tutor();
 $is_courseAdmin = api_is_course_admin();
@@ -135,7 +130,6 @@ Session::write('dropbox_conf', $dropbox_cnf);
 // the dropbox file that contains additional functions
 require_once 'dropbox_functions.inc.php';
 
-
 // protecting the script
 api_protect_course_script();
 
@@ -182,39 +176,39 @@ if ($action == 'add') {
 }
 
 /*	Create javascript and htmlHeaders */
-$javascript = "<script type=\"text/javascript\">
-	function confirmsend ()
-	{
-		if (confirm(\"".get_lang('MailingConfirmSend', '')."\")){
-			return true;
-		} else {
-			return false;
-		}
-		return true;
-	}
+$javascript = "<script>
+function confirmsend()
+{
+    if (confirm(\"".get_lang('MailingConfirmSend', '')."\")){
+        return true;
+    } else {
+        return false;
+    }
+    return true;
+}
 
-	function confirmation (name)
-	{
-		if (confirm(\"".get_lang('ConfirmDelete', '')." : \"+ name )){
-			return true;
-		} else {
-			return false;
-		}
-		return true;
-	}
+function confirmation (name)
+{
+    if (confirm(\"".get_lang('ConfirmDelete', '')." : \"+ name )){
+        return true;
+    } else {
+        return false;
+    }
+    return true;
+}
 
-	function checkForm (frm)
-	{
-		if (frm.elements['recipients[]'].selectedIndex < 0){
-			alert(\"".get_lang('NoUserSelected', '')."\");
-			return false;
-		} else if (frm.file.value == '') {
-			alert(\"".get_lang('NoFileSpecified', '')."\");
-			return false;
-		} else {
-			return true;
-		}
-	}
+function checkForm (frm)
+{
+    if (frm.elements['recipients[]'].selectedIndex < 0){
+        alert(\"".get_lang('NoUserSelected', '')."\");
+        return false;
+    } else if (frm.file.value == '') {
+        alert(\"".get_lang('NoFileSpecified', '')."\");
+        return false;
+    } else {
+        return true;
+    }
+}
 ";
 
 if (dropbox_cnf('allowOverwrite')) {
@@ -294,11 +288,133 @@ $htmlHeadXtra[] = '<meta http-equiv="cache-control" content="no-cache">
 	<meta http-equiv="pragma" content="no-cache">
 	<meta http-equiv="expires" content="-1">';
 
+
 $checked_files = false;
 if (!$view || $view == 'received') {
 	$part = 'received';
 } elseif ($view = 'sent') {
 	$part = 'sent';
+    $htmlHeadXtra[] = api_get_jquery_libraries_js(array('jquery-ui', 'jquery-upload'));
+    $url = api_get_path(WEB_AJAX_PATH).'dropbox.ajax.php?'.api_get_cidreq().'&a=upload_file&id=';
+
+    $htmlHeadXtra[] = "<script>
+$(function () {
+    'use strict';
+    var url = '".$url."';
+    var uploadButton = $('<button/>')
+        .addClass('btn btn-primary')
+        .prop('disabled', true)
+        .text('".get_lang('Loading')."')
+        .on('click', function () {
+            var \$this = $(this),
+            data = \$this.data();
+
+            \$this
+                .off('click')
+                .text('".get_lang('Cancel')."')
+                .on('click', function () {
+                    \$this.remove();
+                    data.abort();
+                });
+            data.submit().always(function () {
+
+                \$this.remove();
+            });
+    });
+
+    $('#recipient_form').on('change', function() {
+        $('#multiple_form').show();
+    });
+
+    $('#fileupload').bind('fileuploaddone', function (e, data) {
+      console.log('fileuploaddone');
+        event.preventDefault();
+        return false;
+    });
+
+    $('#fileupload').submit(function() {
+    return false;
+    });
+
+    $('#fileupload').fileupload({
+        url: url,
+        dataType: 'json',
+        autoUpload: false,
+        // Enable image resizing, except for Android and Opera,
+        // which actually support image resizing, but fail to
+        // send Blob objects via XHR requests:
+        disableImageResize: /Android(?!.*Chrome)|Opera/.test(window.navigator.userAgent),
+        previewMaxWidth: 100,
+        previewMaxHeight: 100,
+        previewCrop: true,
+        complete: function (e, data) {
+        }
+    }).on('fileuploadadd', function (e, data) {
+        data.context = $('<div/>').appendTo('#files');
+
+        $.each(data.files, function (index, file) {
+            var node = $('<p/>').append($('<span/>').text(file.name));
+            if (!index) {
+                node
+                    .append('<br>')
+                    .append(uploadButton.clone(true).data(data));
+            }
+            node.appendTo(data.context);
+        });
+    }).on('fileuploadprocessalways', function (e, data) {
+        var index = data.index,
+            file = data.files[index],
+            node = $(data.context.children()[index]);
+        if (file.preview) {
+            node
+                .prepend('<br>')
+                .prepend(file.preview);
+        }
+        if (file.error) {
+            node
+                .append('<br>')
+                .append($('<span class=\"text-danger\"/>').text(file.error));
+        }
+        if (index + 1 === data.files.length) {
+            data.context.find('button')
+                .text('Upload')
+                .prop('disabled', !!data.files.error);
+        }
+    }).on('fileuploadprogressall', function (e, data) {
+        var progress = parseInt(data.loaded / data.total * 100, 10);
+        $('#progress .progress-bar').css(
+            'width',
+            progress + '%'
+        );
+    }).on('fileuploaddone', function (e, data) {
+        $.each(data.result.files, function (index, file) {
+            if (file.url) {
+                var link = $('<a>')
+                    //.attr('target', '_blank')
+                    .prop('href', file.url);
+
+                $(data.context.children()[index]).wrap(link);
+            } else if (file.error) {
+                var error = $('<span class=\"text-danger\"/>').text(file.error);
+                $(data.context.children()[index])
+                    .append('<br>')
+                    .append(error);
+            }
+        });
+    }).on('fileuploadfail', function (e, data) {
+        $.each(data.files, function (index) {
+            var error = $('<span class=\"text-danger\"/>').text('File upload failed.');
+            $(data.context.children()[index])
+                .append('<br>')
+                .append(error);
+        });
+    }).prop('disabled', !$.support.fileInput)
+        .parent().addClass($.support.fileInput ? undefined : 'disabled');
+
+});
+
+</script>";
+
 } else {
 	header('location: index.php?view='.$view.'&error=Error');
 	exit;
diff --git a/main/dropbox/index.php b/main/dropbox/index.php
index 5ba1c45d7a..57a45631a3 100755
--- a/main/dropbox/index.php
+++ b/main/dropbox/index.php
@@ -63,10 +63,7 @@ if ($action == 'add') {
 if (isset($_POST['submitWork'])) {
 	$check = Security::check_token();
 	if ($check) {
-        $message = store_add_dropbox();
-        if (!empty($message)) {
-            Display :: display_confirmation_message($message);
-        }
+        store_add_dropbox();
 	}
 }
 
diff --git a/main/inc/ajax/document.ajax.php b/main/inc/ajax/document.ajax.php
index 6968643af4..524a1944d2 100755
--- a/main/inc/ajax/document.ajax.php
+++ b/main/inc/ajax/document.ajax.php
@@ -62,27 +62,24 @@ switch ($action) {
                 );
 
                 $json = array();
-                $json['name'] = Display::url(
-                    api_htmlentities($result['title']),
-                    api_htmlentities($result['url']),
-                    array('target'=>'_blank')
-                );
-
-                $json['url'] = $result['url'];
+                if (!empty($result) && is_array($result)) {
+                    $json['name'] = Display::url(
+                        api_htmlentities($result['title']),
+                        api_htmlentities($result['url']),
+                        array('target'=>'_blank')
+                    );
 
-                $json['size'] = format_file_size($file['size']);
-                $json['type'] = api_htmlentities($file['type']);
+                    $json['url'] = $result['url'];
+                    $json['size'] = format_file_size($file['size']);
+                    $json['type'] = api_htmlentities($file['type']);
 
-                if (!empty($result) && is_array($result)) {
                     $json['result'] = Display::return_icon(
                         'accept.png',
                         get_lang('Uploaded')
                     );
                 } else {
-                    $json['result'] = Display::return_icon(
-                        'exclamation.png',
-                        get_lang('Error')
-                    );
+                    $json['url'] = '';
+                    $json['error'] = get_lang('Error');
                 }
                 $resultList[] = $json;
             }
diff --git a/main/inc/ajax/dropbox.ajax.php b/main/inc/ajax/dropbox.ajax.php
new file mode 100644
index 0000000000..9a8de3e00c
--- /dev/null
+++ b/main/inc/ajax/dropbox.ajax.php
@@ -0,0 +1,74 @@
+<?php
+/* For licensing terms, see /license.txt */
+
+/**
+ * Responses to AJAX calls for the document upload
+ */
+require_once '../global.inc.php';
+require_once api_get_path(SYS_CODE_PATH).'dropbox/dropbox_functions.inc.php';
+
+$action = $_REQUEST['a'];
+switch ($action) {
+    case 'upload_file':
+        api_protect_course_script(true);
+        // User access same as upload.php
+        $is_allowed_to_edit = api_is_allowed_to_edit(null, true);
+
+        $recipients = isset($_POST['recipients']) ? $_POST['recipients'] : '';
+
+        if (empty($recipients)) {
+            $resultList[] = ['error' => get_lang('YouMustSelectAtLeastOneDestinee')];
+            echo json_encode(['files' => $resultList]);
+            exit;
+        }
+
+        if (!empty($_FILES)) {
+            $files = $_FILES['files'];
+            $fileList = [];
+            foreach ($files as $name => $array) {
+                $counter = 0;
+                foreach ($array as $data) {
+                    $fileList[$counter][$name] = $data;
+                    $counter++;
+                }
+            }
+
+            $resultList = [];
+            foreach ($fileList as $file) {
+                $globalFile = [];
+                $globalFile['files'] = $file;
+                /** @var Dropbox_SentWork $result */
+                $result = store_add_dropbox($file);
+
+                $json = array();
+
+                if (!empty($result)) {
+
+                    $json['name'] = Display::url(
+                        api_htmlentities($result->title),
+                        api_htmlentities(api_get_path(WEB_CODE_PATH).'dropbox/index.php?'.api_get_cidreq()),
+                        array('target' => '_blank')
+                    );
+
+                    $json['url'] = api_get_path(WEB_CODE_PATH).'dropbox/index.php?'.api_get_cidreq();
+                    $json['size'] = format_file_size($result->filesize);
+                    $json['type'] = api_htmlentities($file['type']);
+                    $json['result'] = Display::return_icon(
+                        'accept.png',
+                        get_lang('Uploaded')
+                    );
+                } else {
+                    $json['result'] = Display::return_icon(
+                        'exclamation.png',
+                        get_lang('Error')
+                    );
+                }
+                $resultList[] = $json;
+            }
+
+            echo json_encode(['files' => $resultList]);
+        }
+        exit;
+        break;
+}
+exit;
diff --git a/main/inc/ajax/work.ajax.php b/main/inc/ajax/work.ajax.php
index 3a15685ad0..db4738cb60 100755
--- a/main/inc/ajax/work.ajax.php
+++ b/main/inc/ajax/work.ajax.php
@@ -44,27 +44,23 @@ switch ($action) {
                 $result = processWorkForm($workInfo, $values, $courseInfo, $sessionId, 0, $userId, $file);
 
                 $json = array();
-                $json['name'] = Display::url(
-                    api_htmlentities($result['title']),
-                    api_htmlentities($result['view_url']),
-                    array('target' => '_blank')
-                );
-
-                $json['url'] = $result['view_url'];
-                //$json['size'] = format_file_size($result['filesize']);
-                $json['size'] = '';
-                $json['type'] = api_htmlentities($result['filetype']);
-
                 if (!empty($result) && is_array($result) && empty($result['error'])) {
+                    $json['name'] = Display::url(
+                        api_htmlentities($result['title']),
+                        api_htmlentities($result['view_url']),
+                        array('target' => '_blank')
+                    );
+
+                    $json['url'] = $result['view_url'];
+                    $json['size'] = '';
+                    $json['type'] = api_htmlentities($result['filetype']);
                     $json['result'] = Display::return_icon(
                         'accept.png',
                         get_lang('Uploaded')
                     );
                 } else {
-                    $json['result'] = Display::return_icon(
-                        'exclamation.png',
-                        get_lang('Error')
-                    );
+                    $json['url'] = '';
+                    $json['error'] = get_lang('Error');
                 }
                 $resultList[] = $json;
             }
diff --git a/main/work/upload.php b/main/work/upload.php
index e94ddc08a7..73a3b37621 100755
--- a/main/work/upload.php
+++ b/main/work/upload.php
@@ -120,8 +120,7 @@ $url = api_get_path(WEB_AJAX_PATH).'work.ajax.php?'.api_get_cidreq().'&a=upload_
 
 $htmlHeadXtra[] = api_get_jquery_libraries_js(array('jquery-ui', 'jquery-upload'));
 $htmlHeadXtra[] = to_javascript_work();
-$htmlHeadXtra[] = "
-<script>
+$htmlHeadXtra[] = "<script>
 $(function () {
     'use strict';
     var url = '".$url."';