The open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.

You can access CacheStorage through the global caches property.

Note: If the specified Cache does not exist, a new cache is created with that cacheName and a Promise that resolves to this new Cache object is returned.

Syntax {
  // Do something with your cache


The name of the cache you want to open.

Return value

A Promise that resolves to the requested Cache object.


This example is from the MDN sw-test example (see sw-test running live). Here we wait for an InstallEvent to fire, then runs waitUntil() to handle the install process for the app. This consists of calling to create a new cache, then using Cache.addAll() to add a series of assets to it.

self.addEventListener('install', function(event) {
  event.waitUntil('v1').then(function(cache) {
      return cache.addAll([


Specification Status Comment
Service Workers
The definition of 'CacheStorage: open' in that specification.
Working Draft Initial definition.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 40Edge Full support 16Firefox Full support 44
Full support 44
Notes Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No support NoOpera Full support 27Safari Full support 11.1WebView Android Full support 40Chrome Android Full support 40Firefox Android Full support 44Opera Android Full support 27Safari iOS Full support YesSamsung Internet Android Full support 4.0


Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
See implementation notes.
See implementation notes.

See also