Web App Manifest made websites install like apps with one JSON file

Mobile operating systems made apps feel tangible: they had icons, names, launch screens and standalone windows. Websites had URLs. The Web App Manifest closed that gap without packaging the site into a native binary.

The W3C specification defines a JSON-based file format for metadata associated with a web application: name, icons, preferred launch URL, orientation, display mode, scope and deep-linking behavior.

MDN describes the manifest's most common use as giving the browser the information needed to install a progressive web app on a device. That made the design choice powerful: a website could remain a website and still become a launchable app.

Put app identity in manifest.json

JSON fit web developers' existing tooling and deployment habits.

A link tag let any page advertise its manifest without a new discovery system.

Scope and start_url gave browsers enough boundaries to launch the right app surface.

Icons and display mode made installable websites feel coherent on a home screen.

When a platform lacks an install step, do not copy the whole app-store model. Standardize the metadata the launcher needs and keep the app on the web.

The Web App Manifest became one of the core pieces of progressive web apps, alongside service workers and HTTPS. Its genius is modest: the browser does the installation because the site supplied the missing identity card.