Cache manifest in HTML5

This article is about obsolete technology for making web pages accessible offline. For regular HTTP cache, see Web cache. For modern technology for creating offline apps, see Progressive web application.

Filename extension	.appcache
Internet media type	text/cache-manifest
Developed by	World Wide Web Consortium
Standard	HTML5
Open format?	Yes
Website	html.spec.whatwg.org/multipage/browsers.html#offline

The cache manifest in HTML5 is an obsolete web browser feature which provided the ability to access a web application even without a network connection. It became part of the W3C Recommendation on 28 October 2014.

Web pages could specify static cache manifests listing all resources used by the page. The browser could download every resource in advance and store it for offline use. In practice, the simple and rigid declarative nature of the format worked well only for very simple pages, falling apart for many interactive websites. In response to this demand, Google Chrome 40 introduced Service Worker API which allows websites to create programmable caches aware of the specifics of its main application logic. Shortly after introduction or Service Workers, browsers deprecated cache manifests. Since 2021, cache manifests are no longer widely available. Browser vendors recommend using service workers instead.

Cache manifests are distinct from web application manifests, a different technology which aims to improve discoverability of progressive web apps and associated metadata.