diff --git a/data/web/admin/system.php b/data/web/admin/system.php
index ed6f64bed..4af2e4b4b 100644
--- a/data/web/admin/system.php
+++ b/data/web/admin/system.php
@@ -126,6 +126,7 @@ $template_data = [
   'mbox_templates' => $mbox_templates,
   'backup_timezone' => getenv('TZ') ?: 'UTC',
   'backup_hostname' => getenv('MAILCOW_HOSTNAME') ?: '',
+  'backup_demo_mode' => $DEMO_MODE,
   'lang_admin' => json_encode($lang['admin']),
   'lang_datatables' => json_encode($lang['datatables'])
 ];
diff --git a/data/web/inc/lib/mailcow/Backup/BackupModule.php b/data/web/inc/lib/mailcow/Backup/BackupModule.php
index c7fc3eedd..034baf846 100644
--- a/data/web/inc/lib/mailcow/Backup/BackupModule.php
+++ b/data/web/inc/lib/mailcow/Backup/BackupModule.php
@@ -39,7 +39,8 @@ use Redis;
  *   process_get_return(BackupModule::fromGlobals()->api->getSettings());
  *   echo json_encode(BackupModule::create($pdo, Context::system(), $config, $redis)->api->export($domain, $page));  // backup.php
  *
- * $config: timezone (TZ of mailcow, for the schedule), alias_disable_external_domains ($ALIAS_DISABLE_EXTERNAL_DOMAINS).
+ * $config: timezone (TZ of mailcow, for the schedule), alias_disable_external_domains ($ALIAS_DISABLE_EXTERNAL_DOMAINS),
+ * demo_mode ($DEMO_MODE: the API changes nothing).
  * $redis: for DKIM keys, rate limits and the domain map (export and restore).
  */
 class BackupModule
@@ -73,15 +74,17 @@ class BackupModule
         $restore = new RestoreService($restoreRepo, $jobRepo, $groups, $sogo, $dovecot, $legacy, (bool)($config['alias_disable_external_domains'] ?? false));
         $domainRestore = new DomainRestoreService($restoreRepo, $jobRepo, $groups, $legacy);
         return new self($settings, $jobs, $export, $restore, $domainRestore,
-            new BackupApiController($settings, $jobs, $export, $restore, $domainRestore, new ApiResponse(Settings::SECRETS)));
+            new BackupApiController($settings, $jobs, $export, $restore, $domainRestore, new ApiResponse(Settings::SECRETS),
+                (bool)($config['demo_mode'] ?? false)));
     }
 
-    /** Legacy entry point for procedural callers: reads $pdo, $redis, $_SESSION, TZ and $ALIAS_DISABLE_EXTERNAL_DOMAINS */
+    /** Legacy entry point for procedural callers: reads $pdo, $redis, $_SESSION, TZ, $ALIAS_DISABLE_EXTERNAL_DOMAINS and $DEMO_MODE */
     public static function fromGlobals(?Context $context = null): self
     {
         return self::create($GLOBALS['pdo'], $context ?? Context::fromSession($_SESSION ?? []), [
             'timezone' => getenv('TZ') ?: 'UTC',
             'alias_disable_external_domains' => ($GLOBALS['ALIAS_DISABLE_EXTERNAL_DOMAINS'] ?? false) === true,
-        ], ($GLOBALS['redis'] ?? null) instanceof Redis ? $GLOBALS['redis'] : null);
+            'demo_mode' => ($GLOBALS['DEMO_MODE'] ?? false) === true,
+        ],($GLOBALS['redis'] ?? null) instanceof Redis ? $GLOBALS['redis'] : null);
     }
 }
diff --git a/data/web/inc/lib/mailcow/Backup/Controller/BackupApiController.php b/data/web/inc/lib/mailcow/Backup/Controller/BackupApiController.php
index 38cd4b764..48619c3c8 100644
--- a/data/web/inc/lib/mailcow/Backup/Controller/BackupApiController.php
+++ b/data/web/inc/lib/mailcow/Backup/Controller/BackupApiController.php
@@ -23,7 +23,8 @@ use PDOException;
 class BackupApiController
 {
     public function __construct(private SettingsService $settings, private JobService $jobs, private ExportService $export,
-        private RestoreService $restore, private DomainRestoreService $domainRestore, private ApiResponse $response)
+        private RestoreService $restore, private DomainRestoreService $domainRestore, private ApiResponse $response,
+        private bool $demoMode = false)
     {
     }
 
@@ -147,11 +148,15 @@ class BackupApiController
     /**
      * Runs one write call: $work gets the log entry and returns the result for process_*_return().
      * A UserError becomes a danger message, a database error stops the call with one `mysql_error` message.
+     * In demo mode no write call runs.
      */
     private function handle(string $action, string $object, mixed $data, callable $work): bool
     {
         $log = ['backup', $action, $object, $data];
         try {
+            if ($this->demoMode) {
+                throw new UserError('demo_mode_enabled');
+            }
             $result = $work($log);
         } catch (UserError $e) {
             $result = $this->response->error($e, $log);
diff --git a/data/web/inc/restore.inc.php b/data/web/inc/restore.inc.php
index e35214495..3f87ec97f 100644
--- a/data/web/inc/restore.inc.php
+++ b/data/web/inc/restore.inc.php
@@ -13,6 +13,7 @@ $template_data = [
   'lang_datatables' => json_encode($lang['datatables']),
   'backup_configured' => \Mailcow\Backup\BackupModule::fromGlobals()->settings->load()->configured(),
   'backup_timezone' => getenv('TZ') ?: 'UTC',
+  'backup_demo_mode' => $DEMO_MODE,
 ];
 
 require_once $_SERVER['DOCUMENT_ROOT'] . '/inc/footer.inc.php';
diff --git a/data/web/lang/lang.de-de.json b/data/web/lang/lang.de-de.json
index eee94f5d3..02301ec11 100644
--- a/data/web/lang/lang.de-de.json
+++ b/data/web/lang/lang.de-de.json
@@ -607,6 +607,7 @@
         "created_from_backup": "Aus dem Backup angelegt",
         "data_added": "Hinzugefügt",
         "deleted_domain_children": "Die Domain wurde gelöscht: Nur die ganze Domain lässt sich wiederherstellen.",
+        "demo_mode": "Demo Mode ist aktiviert: Backups, Wiederherstellungen und Änderungen an den Einstellungen sind gesperrt",
         "details": "Details",
         "domains": "Domains",
         "duration": "Dauer",
diff --git a/data/web/lang/lang.en-gb.json b/data/web/lang/lang.en-gb.json
index 6ffb36569..f8433cf5b 100644
--- a/data/web/lang/lang.en-gb.json
+++ b/data/web/lang/lang.en-gb.json
@@ -607,6 +607,7 @@
         "created_from_backup": "Created from the backup",
         "data_added": "Added",
         "deleted_domain_children": "The domain was deleted: only the whole domain can be restored.",
+        "demo_mode": "Demo Mode is enabled: backups, restores and changes to the settings are disabled",
         "details": "Details",
         "domains": "Domains",
         "duration": "Duration",
diff --git a/data/web/templates/admin/tab-config-backup.twig b/data/web/templates/admin/tab-config-backup.twig
index 34f723bc3..3d1c8df69 100644
--- a/data/web/templates/admin/tab-config-backup.twig
+++ b/data/web/templates/admin/tab-config-backup.twig
@@ -13,6 +13,7 @@
       <div class="row mb-4">
         <div class="col-sm-9 offset-sm-3">
           <p class="text-muted">{{ lang.backup.intro }} <a href="/admin/restore">{{ lang.backup.intro_restore_link }}</a></p>
+          {% if backup_demo_mode %}<div class="alert alert-warning">{{ lang.backup.demo_mode }}</div>{% endif %}
 
           <div id="backup_status">
             <div class="backup-status-summary mb-2" aria-live="polite"><span class="text-muted">{{ lang.footer.loading }}</span></div>
diff --git a/data/web/templates/restore.twig b/data/web/templates/restore.twig
index af9b8af57..f81dabd21 100644
--- a/data/web/templates/restore.twig
+++ b/data/web/templates/restore.twig
@@ -10,6 +10,7 @@
       <span>{{ lang.backup.restore_card }}</span>
     </div>
     <div class="card-body">
+      {% if backup_demo_mode %}<div class="alert alert-warning">{{ lang.backup.demo_mode }}</div>{% endif %}
       <div class="backup-restore-hints"></div>
       {# left-aligned with the search of the toolbar below #}
       <div class="d-flex flex-wrap align-items-center gap-2 mb-3 px-2">
diff --git a/tests/php/Backup/Controller/BackupApiControllerTest.php b/tests/php/Backup/Controller/BackupApiControllerTest.php
index 3b6dd7d1d..52579ac77 100644
--- a/tests/php/Backup/Controller/BackupApiControllerTest.php
+++ b/tests/php/Backup/Controller/BackupApiControllerTest.php
@@ -81,6 +81,26 @@ class BackupApiControllerTest extends TestCase
         $this->assertSame(['backup', 'delete', 'job', ['id' => [4, '7', 'x']]], $_SESSION['return'][4]['log']);
     }
 
+    public function testDemoModeChangesNothing(): void
+    {
+        $this->settings->expects($this->never())->method('save');
+        foreach (['create', 'restore', 'cancel'] as $method) {
+            $this->jobs->expects($this->never())->method($method);
+        }
+        $this->jobs->method('status')->willReturn(['configured' => false]);
+        $api = new BackupApiController($this->settings, $this->jobs, $this->createMock(ExportService::class), $this->restore,
+            $this->domainRestore, new ApiResponse(Settings::SECRETS), true);
+
+        $this->assertFalse($api->editSettings(['target' => 's3', 's3_endpoint' => 'https://s3.example.org']));
+        $this->assertFalse($api->addJob(['type' => 'backup']));
+        $this->assertFalse($api->addRestore(['snapshot' => 'abc']));
+        $this->assertFalse($api->deleteJobs([4]));
+
+        $this->assertSame(array_fill(0, 4, ['danger', 'demo_mode_enabled']),
+            array_map(fn(array $m): array => [$m['type'], $m['msg']], $_SESSION['return']));
+        $this->assertSame(['configured' => false], $api->getStatus());
+    }
+
     public function testReads(): void
     {
         $this->jobs->method('get')->willReturnCallback(fn(int $id): ?Job => ($id === 4) ? self::job(4, 'backup') : null);