Cache manifest in HTML5

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.

Cache manifests enabled web pages to statically declare 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. Many interactive websites and single page required a dynamic, programmable storage logic. In response to this demand, Google Chrome 40 introduced Service Worker API which allows websites to register a script which runs in the user's browser and functions like a proxy (or a middleman) between the visible page and the network. Such Service Workers provide a programmable cache aware of the specifics of its main application logic, has access to information about user's current network connection and can support explicit invocations by the user. Shortly after introduction or Service Workers, browsers deprecated cache manifests.

Since 2021, this technology is no longer widely available. It was removed from Firefox 85, and disabled by default in Chrome 84 and removed in Chrome 95. Using any of the offline Web application features at this time is highly discouraged and use of service workers is recommended instead. Cache manifests are distinct from web application manifests, a JSON-based file format which is part of the progressive web app technology, and as of 2026 is currently active and going through the standardization process at the W3C.