Service Worker Test What does the service worker do to your page?

The test finds the service worker and shows what your page uses it for. You see what a crawler gets on the first visit without it.

Websites that verify Googlebot by IP recognize an imitated user agent and then often respond differently.
We store the request with your IP address to run the tool. More in the privacy policy.
How the test works

Four steps to the result

The test opens the page like a new visitor and analyzes what happens.

First visitThe page is rendered like for a new visitor, without an active service worker. This is how Googlebot gets every page too.
Find the registrationThe test searches the source code, the rendered HTML and up to 15 of the page's scripts.
Read the scriptScope, caching strategies, precache, push and offline page are analyzed. The test fetches the offline page and up to 10 cached files directly.
Compare signalsStatus code, title, canonical, meta robots, H1, words and links for the selected user agent, for Chrome and in the rendered version.
What you need the test for

What returning visitors see is not always what Googlebot sees

Googlebot keeps no state between two fetches. Every fetch is a first visit, where the service worker does not control the page yet.

  • After a releaseA framework update or a PWA plugin sometimes brings a service worker along. The test shows whether that happened.
  • When subpages look emptyIf title, H1 or text are missing on the first visit, the signals show it.
  • Before a relaunchRecord which service worker runs today and what it stores in the cache.
Guide: service workers and SEO
Example resultExcerpt
Scope /Workbox detectedOffline page availablePage requests interceptedTitle and H1 present on first visit

Green: OK. Blue: note. Orange: take a closer look.

Frequently asked questions

Does Googlebot run service workers?
Google documents that the Web Rendering Service keeps no state between two page loads. Every fetch is therefore a first visit, where a service worker doesn't control the page yet. For search, what counts is what the page delivers without it.
Why doesn't the test find a service worker even though one is running?
The test looks for the registration in the source code, in the rendered HTML and in up to 15 of the page's scripts. If the script address is only built at runtime or the script only loads after a user action, the test doesn't find it. In Chrome, DevTools show under Application, Service Workers what is really registered.
Does the test also show the visit with an active service worker?
For now, the test shows the first visit without a service worker, the way Googlebot gets the page. A second visit with an active service worker and a visit without a network connection aren't part of it yet. Both are planned. From the script, the test works out whether page requests are intercepted and which offline page is set up.
Which user agent should I choose?
searchVIUbot is the default. The test compares the selected user agent with Chrome on the same device. If a website blocks unknown bots, allowlisting the searchVIUbot IP addresses helps.
Demo

What does your website look like in searchVIU?

After a short call about crawler access and Search Console, Michael shows you searchVIU with your website and a demo project. The demo takes around 30 minutes.

Request a demo