What are service workers?

Service workers are JavaScript scripts that run in the background, separate from the web page. They intercept network requests, manage caching, and enable offline functionality. They are the foundation of Progressive Web Apps (PWAs) and are registered per origin and scope.

How it works

A service worker goes through a lifecycle: installing → waiting → active. Once active, it controls all pages within its scope. The Cache Storage API lets workers store request/response pairs for offline access. This tool reads from navigator.serviceWorker and the CacheStorage API to display registered workers and cached resources.

How to use this tool

• View all registered service workers for the current origin with their state and scope
• Browse Cache Storage entries and inspect cached URLs
• Unregister workers or delete caches directly from the browser

Common use cases

• Debugging PWA caching issues and stale content
• Checking which service worker version is active after a deployment
• Clearing cached assets when testing new builds
• Verifying service worker scope and registration status