The manifest file is one of the basic building blocks of a Progressive Web App (PWA). It is a simple JSON file stored in the root of your server’s web directory that lists properties of your app, including the name, icons and theme colors, orientation of the app, and much more.
Along with the other technologies, the manifest file allows you to create a web app with performance and experience that rivals that of native apps. Users will be able to install the app on the device’s home screen directly from the web, use the app when offline, and receive push notifications. This will allow companies to focus on building a single app that provides a great experience for web and native users.
At the time of writing, caniuse reports that only Chrome, Chrome for Android, and the Samsung browser support the Web App Manifest. Those three browsers alone provide support for 59% of all internet users.
The other top three browsers, Microsoft Edge, FireFox, and Safari (WebKit) are listed as in development. So, it will only be a matter of time before we see support in those browsers.
As with other features of a Progressive Web App, the lack of browser support is not a deterrent. These features only enhance the experience of users on supported platforms and do not significantly degrade the experience on platforms without support.