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Nutter Tools

A free toolbox that runs in your browser. A tool for every job.

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© Nutter Toolsnutter.tools
  1. Home
  2. Web & auth
  3. Service worker checker
Your files stay on your device

Service worker checker

Fetch a page URL and its service worker script through the capped proxy, locate the page's service-worker register call, and statically report on HTTPS scheme, MIME type, install, activate, fetch, and message handlers, and Cache API use without executing anything.

This tool is in beta

Still being tested. If a result looks wrong, tell us.

Report a problem

Static inspection, never execution

This tool reads a page's markup and its worker script as text. The worker never runs here, and no registration is created in your browser.

A static read has honest blind spots. A registration added by a separate bundle, an argument built at runtime instead of a quoted string, or listeners attached through a helper instead of a literal addEventListener call will not show up here, and this tool does not claim a site's offline mode works or that it would pass a Lighthouse audit. It reports what the text contains.

Target

http or https, fetched through this project's capped proxy

What leaves your browser

Two GET requests leave this page, both through the project's proxy: one for the page HTML, one for the worker script it registers. The proxy caps size and time, refuses private hosts, and never follows redirects. This page leaves your browser only when you press the button; never on load, never in the background. Nothing is sent anywhere else. Google Analytics still measures the visit to this page, and it never receives what you run through this tool.

Each response is read as text up to the proxy's decoded prefix of 4,096 characters; markup past that window is invisible to this check, and the report flags it.

Runs on this device. Nothing is uploaded.

More web & auth tools

  • HTTP header parser
  • CSP evaluator & builder
All web & auth tools

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