diff --git a/.github/workflows/rebase.yml b/.github/workflows/rebase.yml
new file mode 100644
index 000000000..c23336d4d
--- /dev/null
+++ b/.github/workflows/rebase.yml
@@ -0,0 +1,22 @@
+on:
+  issue_comment:
+    types: [created]
+name: Rebase automatique
+jobs:
+  rebase:
+    name: Rebase
+    if: github.event.issue.pull_request != '' && contains(github.event.comment.body, '/rebase')
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Automatic Rebase
+      uses: cirrus-actions/rebase@master
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+  # https://github.community/t5/GitHub-Actions/Workflow-is-failing-if-no-job-can-be-ran-due-to-condition/m-p/38186#M3250
+  always_job:
+    name: Aways run job
+    runs-on: ubuntu-latest
+    steps:
+      - name: Always run
+        run: echo "This job is used to prevent the workflow to fail when all other jobs are skipped."
diff --git a/app/assets/stylesheets/new_design/animations.scss b/app/assets/stylesheets/new_design/animations.scss
index c9df122d2..4cb79aa38 100644
--- a/app/assets/stylesheets/new_design/animations.scss
+++ b/app/assets/stylesheets/new_design/animations.scss
@@ -16,3 +16,21 @@
   @extend %animation;
   animation-name: fade-in-down;
 }
+
+@keyframes pulse {
+  0% {
+    transform: scale(1, 1);
+  }
+
+  10% {
+    transform: scale(0.9, 0.9);
+  }
+
+  70% {
+    transform: scale(1.3, 1.3);
+  }
+
+  100% {
+    transform: scale(1, 1);
+  }
+}
diff --git a/app/assets/stylesheets/new_design/autosave.scss b/app/assets/stylesheets/new_design/autosave.scss
new file mode 100644
index 000000000..a12582635
--- /dev/null
+++ b/app/assets/stylesheets/new_design/autosave.scss
@@ -0,0 +1,123 @@
+@import "colors";
+@import "constants";
+
+.autosave {
+  position: relative;
+  font-size: 0.9em;
+}
+
+.autosave-explanation {
+  color: $grey;
+  margin-left: 4px;
+}
+
+.autosave-explanation-text,
+.autosave-label {
+  margin-right: 6px;
+}
+
+.autosave-more-infos {
+  white-space: nowrap;
+}
+
+.autosave-status {
+  // Position the status over the explanation text
+  position: absolute;
+  top: 0;
+
+  &.succeeded .autosave-label {
+    color: $green;
+  }
+
+  &.failed .autosave-label {
+    color: $orange;
+  }
+}
+
+.autosave-icon {
+  display: inline-block;
+  vertical-align: -1px;
+  margin-right: 4px;
+}
+
+.autosave-icon.icon.accept {
+  vertical-align: -8px;
+}
+
+.autosave-retry {
+  &:disabled {
+    .autosave-retry-label {
+      display: none;
+    }
+  }
+
+  &:not(:disabled) {
+    cursor: pointer;
+
+    .autosave-retrying-label {
+      display: none;
+    }
+  }
+}
+
+$autosave-status-fade-in-duration: 0.2s;
+$autosave-status-fade-out-duration: 0.7s;
+
+// By default (and in the idle state), display the explanation text and hide statuses.
+.autosave-explanation {
+  visibility: visible;
+  opacity: 1;
+  // Make the explanation fade-in slowly when the status is being removed
+  transition-property: opacity;
+  transition-duration: $autosave-status-fade-out-duration;
+}
+
+.autosave-status {
+  visibility: hidden;
+  opacity: 0;
+  // Make the status fade-out slowly when being removed
+  transition-property: opacity, visibility;
+  transition-duration: $autosave-status-fade-out-duration;
+}
+
+// When one of the status messages should be displayed:
+.autosave-state-succeeded,
+.autosave-state-failed {
+  // Hide the explanation
+  .autosave-explanation {
+    visibility: hidden;
+    opacity: 0;
+    // Make the explanation fade-out quickly
+    transition-property: opacity, visibility;
+    transition-duration: $autosave-status-fade-in-duration;
+  }
+
+  // Show the status message (succeeded or failed)
+  .autosave-status.succeeded,
+  .autosave-status.failed {
+    opacity: 1;
+    // Make the status message fade-in quickly
+    transition-property: opacity;
+    transition-duration: $autosave-status-fade-in-duration;
+  }
+
+  // Make the icon pulse (if any)
+  .autosave-icon {
+    opacity: 1;
+    // Make the icon pulse after being made visible
+    animation-name: pulse;
+    animation-duration: 0.25s;
+    animation-delay: 0.15s;
+    animation-timing-function: linear;
+    animation-fill-mode: backwards;
+  }
+}
+
+// Show only the relevant status message (succeeded of failed)
+.autosave-state-succeeded .autosave-status.succeeded {
+  visibility: visible;
+}
+
+.autosave-state-failed .autosave-status.failed {
+  visibility: visible;
+}
diff --git a/app/assets/stylesheets/new_design/dossier_edit.scss b/app/assets/stylesheets/new_design/dossier_edit.scss
index ad0490cfd..05096311e 100644
--- a/app/assets/stylesheets/new_design/dossier_edit.scss
+++ b/app/assets/stylesheets/new_design/dossier_edit.scss
@@ -70,13 +70,13 @@
     border-top-right-radius: 5px;
     border-bottom: none;
 
-    .button {
+    .button:not(:small) {
       min-height: 38px;
       line-height: 16px;
     }
 
     // If there are more than one button, align the "Send" button to the right
-    .button:not(:first-of-type).send {
+    .button:not(:first-child).send {
       margin-left: auto;
     }
 
@@ -92,4 +92,10 @@
       padding-bottom: $default-spacer;
     }
   }
+
+  .autosave {
+    // Make the autosave block occupy the entire horizontal space,
+    // to ensure the failed state has room to display its content.
+    flex-grow: 1;
+  }
 }
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index a48d3b33b..527bf34c7 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -16,6 +16,7 @@ class ApplicationController < ActionController::Base
 
   before_action :staging_authenticate
   before_action :set_active_storage_host
+  before_action :setup_javascript_settings
   before_action :setup_tracking
 
   helper_method :multiple_devise_profile_connect?, :instructeur_signed_in?, :current_instructeur,
@@ -114,6 +115,10 @@ class ApplicationController < ActionController::Base
     ActiveStorage::Current.host = request.base_url
   end
 
+  def setup_javascript_settings
+    gon.autosave = Rails.application.config.ds_autosave
+  end
+
   def setup_tracking
     gon.matomo = matomo_config
     gon.sentry = sentry_config
diff --git a/app/helpers/dossier_helper.rb b/app/helpers/dossier_helper.rb
index db1ffa829..bc6f7a218 100644
--- a/app/helpers/dossier_helper.rb
+++ b/app/helpers/dossier_helper.rb
@@ -31,6 +31,18 @@ module DossierHelper
     end
   end
 
+  def dossier_form_class(dossier)
+    classes = ['form']
+    if autosave_available?(dossier)
+      classes << 'autosave-enabled'
+    end
+    classes.join(' ')
+  end
+
+  def autosave_available?(dossier)
+    dossier.brouillon? && Flipper.enabled?(:autosave_dossier_draft, dossier.user)
+  end
+
   def dossier_submission_is_closed?(dossier)
     dossier.brouillon? && dossier.procedure.archivee?
   end
diff --git a/app/javascript/new_design/autosave-controller.js b/app/javascript/new_design/autosave-controller.js
new file mode 100644
index 000000000..3d2c1acff
--- /dev/null
+++ b/app/javascript/new_design/autosave-controller.js
@@ -0,0 +1,92 @@
+import { fire, timeoutable } from '@utils';
+
+// Manages a queue of Autosave operations,
+// and sends `autosave:*` events to indicate the state of the requests.
+export default class AutosaveController {
+  constructor() {
+    this.timeoutDelay = 60000; // 1mn
+    this.latestPromise = Promise.resolve();
+  }
+
+  // Add a new autosave request to the queue.
+  // It will be started after the previous one finishes (to prevent older form data
+  // to overwrite newer data if the server does not repond in order.)
+  enqueueAutosaveRequest(form) {
+    this.latestPromise = this.latestPromise.finally(() => {
+      return this._sendAutosaveRequest(form)
+        .then(this._didSucceed)
+        .catch(this._didFail);
+    });
+    this._didEnqueue();
+  }
+
+  // Create a fetch request that saves the form.
+  // Returns a promise fulfilled when the request completes.
+  _sendAutosaveRequest(form) {
+    const autosavePromise = new Promise((resolve, reject) => {
+      if (!document.body.contains(form)) {
+        return reject(new Error('The form can no longer be found.'));
+      }
+
+      const [formData, formDataError] = this._formDataForDraft(form);
+      if (formDataError) {
+        formDataError.message = `Error while generating the form data (${formDataError.message})`;
+        return reject(formDataError);
+      }
+
+      const fetchOptions = {
+        method: form.method,
+        body: formData,
+        headers: { Accept: 'application/json' }
+      };
+
+      return window.fetch(form.action, fetchOptions).then(response => {
+        if (response.ok) {
+          resolve(response);
+        } else {
+          const message = `Network request failed (${response.status}, "${response.statusText}")`;
+          reject(new Error(message));
+        }
+      });
+    });
+
+    // Time out the request after a while, to avoid recent requests not starting
+    // because an older one is stuck.
+    return timeoutable(autosavePromise, this.timeoutDelay);
+  }
+
+  // Extract a FormData object of the form fields.
+  _formDataForDraft(form) {
+    // File inputs are handled separatly by ActiveStorage:
+    // exclude them from the draft (by disabling them).
+    // (Also Safari has issue with FormData containing empty file inputs)
+    const fileInputs = form.querySelectorAll(
+      'input[type="file"]:not([disabled])'
+    );
+    fileInputs.forEach(fileInput => (fileInput.disabled = true));
+
+    // Generate the form data
+    let formData = null;
+    try {
+      formData = new FormData(form);
+      return [formData, null];
+    } catch (error) {
+      return [null, error];
+    } finally {
+      // Re-enable disabled file inputs
+      fileInputs.forEach(fileInput => (fileInput.disabled = false));
+    }
+  }
+
+  _didEnqueue() {
+    fire(document, 'autosave:enqueue');
+  }
+
+  _didSucceed(response) {
+    fire(document, 'autosave:end', response);
+  }
+
+  _didFail(error) {
+    fire(document, 'autosave:error', error);
+  }
+}
diff --git a/app/javascript/new_design/autosave.js b/app/javascript/new_design/autosave.js
new file mode 100644
index 000000000..2e837491f
--- /dev/null
+++ b/app/javascript/new_design/autosave.js
@@ -0,0 +1,85 @@
+import AutosaveController from './autosave-controller.js';
+import {
+  debounce,
+  delegate,
+  fire,
+  enable,
+  disable,
+  hasClass,
+  addClass,
+  removeClass
+} from '@utils';
+
+const AUTOSAVE_DEBOUNCE_DELAY = gon.autosave.debounce_delay;
+const AUTOSAVE_STATUS_VISIBLE_DURATION = gon.autosave.status_visible_duration;
+
+// Create a controller responsible for queuing autosave operations.
+const autosaveController = new AutosaveController();
+
+// Whenever a 'change' event is triggered on one of the form inputs, try to autosave.
+
+const formSelector = 'form#dossier-edit-form.autosave-enabled';
+const formInputsSelector = `${formSelector} input, ${formSelector} select, ${formSelector} textarea`;
+
+delegate(
+  'change',
+  formInputsSelector,
+  debounce(() => {
+    const form = document.querySelector(formSelector);
+    autosaveController.enqueueAutosaveRequest(form);
+  }, AUTOSAVE_DEBOUNCE_DELAY)
+);
+
+delegate('click', '.autosave-retry', () => {
+  const form = document.querySelector(formSelector);
+  autosaveController.enqueueAutosaveRequest(form);
+});
+
+// Display some UI during the autosave
+
+addEventListener('autosave:enqueue', () => {
+  disable(document.querySelector('button.autosave-retry'));
+});
+
+addEventListener('autosave:end', () => {
+  enable(document.querySelector('button.autosave-retry'));
+  setState('succeeded');
+  hideSucceededStatusAfterDelay();
+});
+
+addEventListener('autosave:error', event => {
+  enable(document.querySelector('button.autosave-retry'));
+  setState('failed');
+  logError(event.detail);
+});
+
+function setState(state) {
+  const autosave = document.querySelector('.autosave');
+  if (autosave) {
+    // Re-apply the state even if already present, to get a nice animation
+    removeClass(autosave, 'autosave-state-idle');
+    removeClass(autosave, 'autosave-state-succeeded');
+    removeClass(autosave, 'autosave-state-failed');
+    autosave.offsetHeight; // flush animations
+    addClass(autosave, `autosave-state-${state}`);
+  }
+}
+
+function hideSucceededStatus() {
+  const autosave = document.querySelector('.autosave');
+  if (hasClass(autosave, 'autosave-state-succeeded')) {
+    setState('idle');
+  }
+}
+const hideSucceededStatusAfterDelay = debounce(
+  hideSucceededStatus,
+  AUTOSAVE_STATUS_VISIBLE_DURATION
+);
+
+function logError(error) {
+  if (error && error.message) {
+    error.message = `[Autosave] ${error.message}`;
+    console.error(error);
+    fire(document, 'sentry:capture-exception', error);
+  }
+}
diff --git a/app/javascript/packs/application.js b/app/javascript/packs/application.js
index 9b956474a..c8952609c 100644
--- a/app/javascript/packs/application.js
+++ b/app/javascript/packs/application.js
@@ -20,6 +20,7 @@ import '../shared/franceconnect';
 import '../shared/toggle-target';
 
 import '../new_design/dropdown';
+import '../new_design/autosave';
 import '../new_design/form-validation';
 import '../new_design/procedure-context';
 import '../new_design/procedure-form';
diff --git a/app/javascript/shared/utils.js b/app/javascript/shared/utils.js
index f50bc15ac..9be438b76 100644
--- a/app/javascript/shared/utils.js
+++ b/app/javascript/shared/utils.js
@@ -17,6 +17,26 @@ export function toggle(el) {
   el && el.classList.toggle('hidden');
 }
 
+export function enable(el) {
+  el && (el.disabled = false);
+}
+
+export function disable(el) {
+  el && (el.disabled = true);
+}
+
+export function hasClass(el, cssClass) {
+  return el && el.classList.contains(cssClass);
+}
+
+export function addClass(el, cssClass) {
+  el && el.classList.add(cssClass);
+}
+
+export function removeClass(el, cssClass) {
+  el && el.classList.remove(cssClass);
+}
+
 export function delegate(eventNames, selector, callback) {
   eventNames
     .split(' ')
@@ -66,6 +86,16 @@ function offset(element) {
   };
 }
 
+// Takes a promise, and return a promise that times out after the given delay.
+export function timeoutable(promise, timeoutDelay) {
+  let timeoutPromise = new Promise((resolve, reject) => {
+    setTimeout(() => {
+      reject(new Error(`Promise timed out after ${timeoutDelay}ms`));
+    }, timeoutDelay);
+  });
+  return Promise.race([promise, timeoutPromise]);
+}
+
 const DATA_ACTIVE_REQUESTS_COUNT = 'data-active-requests-count';
 
 function incrementActiveRequestsCount() {
diff --git a/app/mailers/devise_user_mailer.rb b/app/mailers/devise_user_mailer.rb
index a19c04768..de07cc1b7 100644
--- a/app/mailers/devise_user_mailer.rb
+++ b/app/mailers/devise_user_mailer.rb
@@ -4,6 +4,11 @@ class DeviseUserMailer < Devise::Mailer
   include Devise::Controllers::UrlHelpers # Optional. eg. `confirmation_url`
   layout 'mailers/layout'
 
+  # Don’t retry to send a message if the server rejects the recipient address
+  rescue_from Net::SMTPSyntaxError do |_error|
+    message.perform_deliveries = false
+  end
+
   def template_paths
     ['devise_mailer']
   end
diff --git a/app/views/shared/dossiers/_edit.html.haml b/app/views/shared/dossiers/_edit.html.haml
index 7691145af..b0b353520 100644
--- a/app/views/shared/dossiers/_edit.html.haml
+++ b/app/views/shared/dossiers/_edit.html.haml
@@ -8,7 +8,7 @@
   - else
     - form_options = { url: modifier_dossier_url(dossier), method: :patch }
 
-  = form_for dossier, form_options.merge({ html: { id: 'dossier-edit-form', class: 'form', multipart: true } }) do |f|
+  = form_for dossier, form_options.merge({ html: { id: 'dossier-edit-form', class: dossier_form_class(dossier), multipart: true } }) do |f|
 
     .prologue
       %p.mandatory-explanation
@@ -17,7 +17,10 @@
         ) sont obligatoires.
       - if dossier.brouillon?
         %p.mandatory-explanation
-          Pour enregistrer votre dossier et le reprendre plus tard, cliquez sur le bouton « Enregistrer le brouillon » en bas à gauche du formulaire.
+          - if autosave_available?(dossier)
+            Votre dossier est enregistré automatiquement après chaque modification. Vous pouvez à tout moment fermer la fenêtre et reprendre plus tard là où vous en étiez.
+          - else
+            Pour enregistrer votre dossier et le reprendre plus tard, cliquez sur le bouton « Enregistrer le brouillon » en bas à gauche du formulaire.
 
       - if notice_url(dossier.procedure).present?
         = link_to notice_url(dossier.procedure), target: '_blank', rel: 'noopener', class: 'button notice', title: "Pour vous aider à remplir votre dossier, vous pouvez consulter le guide de cette démarche." do
@@ -41,11 +44,13 @@
     - if !apercu
       .send-dossier-actions-bar
         - if dossier.brouillon?
-          = f.button 'Enregistrer le brouillon',
-            formnovalidate: true,
-            value: true,
-            class: 'button send secondary',
-            data: { 'disable-with': "Envoi en cours…" }
+          - if autosave_available?(dossier)
+            = render partial: 'users/dossiers/autosave'
+          - else
+            = f.button 'Enregistrer le brouillon',
+              formnovalidate: true,
+              class: 'button send secondary',
+              data: { 'disable-with': "Envoi en cours…" }
 
           - if dossier.can_transition_to_en_construction?
             = f.button 'Déposer le dossier',
diff --git a/app/views/users/dossiers/_autosave.html.haml b/app/views/users/dossiers/_autosave.html.haml
new file mode 100644
index 000000000..c19bdc030
--- /dev/null
+++ b/app/views/users/dossiers/_autosave.html.haml
@@ -0,0 +1,21 @@
+- more_infos_url = 'https://faq.demarches-simplifiees.fr/article/73-enregistrer-mon-dossier?preview=5dcbf0bb2c7d3a7e9ae3e33f'
+
+.autosave.autosave-state-idle
+  %p.autosave-explanation
+    %span.autosave-explanation-text
+      Votre brouillon est automatiquement enregistré.
+    = link_to 'En savoir plus', more_infos_url, target: '_blank', rel: 'noopener', class: 'autosave-more-infos'
+
+  %p.autosave-status.succeeded
+    %span.autosave-icon.icon.accept
+    %span.autosave-label
+      Brouillon enregistré
+    = link_to 'En savoir plus', more_infos_url, target: '_blank', rel: 'noopener', class: 'autosave-more-infos'
+
+  %p.autosave-status.failed
+    %span.autosave-icon ⚠️
+    %span.autosave-label Impossible d’enregistrer le brouillon
+    %button.button.small.autosave-retry
+      %span.autosave-retry-label réessayer
+      %span.autosave-retrying-label enregistrement en cours…
+
diff --git a/config/application.rb b/config/application.rb
index b42657278..65080acaf 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -40,8 +40,14 @@ module TPS
       Administrate::ApplicationController.helper(TPS::Application.helpers)
     end
 
-    config.ds_weekly_overview = ENV['APP_NAME'] == 'tps'
     config.middleware.use Rack::Attack
     config.middleware.use Flipper::Middleware::Memoizer, preload_all: true
+
+    config.ds_weekly_overview = ENV['APP_NAME'] == 'tps'
+
+    config.ds_autosave = {
+      debounce_delay: 3000,
+      status_visible_duration: 6000
+    }
   end
 end
diff --git a/config/environments/test.rb b/config/environments/test.rb
index 0f05338b6..7f100ca27 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -53,4 +53,9 @@ Rails.application.configure do
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+
+  config.ds_autosave = {
+    debounce_delay: 500,
+    status_visible_duration: 500
+  }
 end
diff --git a/config/initializers/flipper.rb b/config/initializers/flipper.rb
index df7bcfdd2..d434f6a72 100644
--- a/config/initializers/flipper.rb
+++ b/config/initializers/flipper.rb
@@ -30,6 +30,7 @@ features = [
   :administrateur_web_hook,
   :insee_api_v3,
   :instructeur_bypass_email_login_token,
+  :autosave_dossier_draft,
   :maintenance_mode,
   :mini_profiler,
   :operation_log_serialize_subject,
diff --git a/spec/features/users/brouillon_spec.rb b/spec/features/users/brouillon_spec.rb
index b6c284cbb..90bea2630 100644
--- a/spec/features/users/brouillon_spec.rb
+++ b/spec/features/users/brouillon_spec.rb
@@ -186,6 +186,47 @@ feature 'The user' do
     expect(page).to have_no_text('RIB.pdf')
   end
 
+  context 'when the draft autosave is enabled' do
+    before do
+      Flipper.enable_actor(:autosave_dossier_draft, user)
+    end
+
+    scenario 'autosave a draft', js: true do
+      log_in(user, simple_procedure)
+      fill_individual
+
+      expect(page).not_to have_button('Enregistrer le brouillon')
+      expect(page).to have_content('Votre brouillon est automatiquement enregistré')
+
+      fill_in('texte obligatoire', with: 'a valid user input')
+      blur
+
+      expect(page).to have_css('span', text: 'Brouillon enregistré', visible: true)
+
+      visit current_path
+      expect(page).to have_field('texte obligatoire', with: 'a valid user input')
+    end
+
+    scenario 'retry on autosave error', js: true do
+      log_in(user, simple_procedure)
+      fill_individual
+
+      # Test autosave failure
+      logout(:user) # Make the subsequent autosave requests fail
+      fill_in('texte obligatoire', with: 'a valid user input')
+      blur
+      expect(page).to have_css('span', text: 'Impossible d’enregistrer le brouillon', visible: true)
+
+      # Test that retrying after a failure works
+      login_as(user, scope: :user) # Make the autosave requests work again
+      click_on 'réessayer'
+      expect(page).to have_css('span', text: 'Brouillon enregistré', visible: true)
+
+      visit current_path
+      expect(page).to have_field('texte obligatoire', with: 'a valid user input')
+    end
+  end
+
   private
 
   def log_in(user, procedure)