---
title: "Offline support / service worker"
manual: "PWA Manifest"
version: "main"
permalink: "https://docs.typo3.org/permalink/woit/wit-pwamanifest:offline-support@main"
source: "OfflineSupport/Index.rst"
rendered: "2026-10-17T07:19:19+00:00"
---

# Offline support / service worker {#offline-support}

Tab **PWA Offline / Service Worker** in the site configuration.

![Site configuration tab "PWA Offline / Service Worker"](../Images/Wit_PWAManifest_ServiceWorker.png)

-   **WitPwamanifestServiceWorkerEnabled**

    -   *Type:* boolean
    -   *Default:* false

    Label **Enable service worker / offline support**. If enabled, a
    script that registers the service worker is added to the
    `<head>` of every page.

-   **WitPwamanifestOfflinePageUrl**

    -   *Type:* string (link)

    Label **Offline fallback page**. Page shown when a page navigation
    fails because there is no network connection. If empty,
    [WitPwamanifestStartUrl](https://docs.typo3.org/permalink/woit/wit-pwamanifest:confval-site-start-url@main) is used. If [WitPwamanifestStartUrl](https://docs.typo3.org/permalink/woit/wit-pwamanifest:confval-site-start-url@main) is empty
    too, `/` is used.

## Behaviour {#offline-support-behaviour}

-   The script is delivered via `typeNum = 836` with the header
    `Service-Worker-Allowed: /` and registered with `scope: '/'`. No route
    enhancer and no file in the document root are required.
-   **Install:** the offline fallback page is stored in the cache
    `wit-pwa-offline-v2`.
-   **Activate:** all other caches of the origin are deleted.
-   **Page navigation:** network first. If the request fails, the cached
    offline fallback page is returned.
-   **Styles, scripts, fonts and images:** cache first. Successful responses
    are stored in the cache when they are requested for the first time.
    Assets requested before are served from the cache, also offline.
-   Requests other than `GET` and requests with a scheme other than
    `http`/`https` (for example from browser extensions) are not handled.
-   The scope `/` covers the whole origin, including the TYPO3 backend
    under `/typo3/`. Backend styles, scripts, fonts and images are
    therefore stored in the cache as well.

> [!IMPORTANT]
> The service worker is intentionally minimal: there is no configurable
> caching strategy and no cache versioning per deployment.
>
> Assets are cached by their full URL. TYPO3 adds the file modification time
> to asset URLs (for example `backend.css?1791380894`), so a changed
> file gets a new URL and is loaded from the network. The entry for the old
> URL stays in the cache until the cache name changes in a new extension
> version.

## Disable the service worker {#offline-support-disable}

Disabling the option only stops the registration on new page loads. A service
worker that is already installed in a browser stays active until it is
unregistered (for example via the browser developer tools).