What is the WEBMANIFEST file format?
A .webmanifest file is the Web Application Manifest, a JSON document that a browser reads to install and display a Progressive Web App (PWA). It holds a single JSON object whose members describe the app: name, short_name, icons, start_url, scope, display, background_color, and theme_color, among others. When you add a PWA to a phone home screen or a desktop, these values decide the app icon, its title, and how the window opens.
The format is a W3C standard, first drafted in 2013 and supported in browsers from Chrome 45 in 2015. A page links to it in the HTML head:
<link rel="manifest" href="/app.webmanifest">The registered media type is application/manifest+json. The .webmanifest extension is the one IANA registered, though many sites still name the file manifest.json. Both work as long as the server sends a JSON-valid content type.
Security & safety
RISK: LOWA .webmanifest file is plain-text JSON with no executable code, so opening it cannot run anything on your machine. The only practical risk is that a manifest can declare protocol_handlers or file_handlers that register a PWA to handle links or file types once the app is installed, which is a browser-mediated permission, not an action of opening the file. Editing an invalid manifest can break PWA installation but poses no security threat.
Format details
in a nutshell- Firefox WebExtension manifest - Browser extensions use a manifest file, but it is named manifest.json with a .json extension, not .webmanifest.
- Java JAR/app manifests - Unrelated MANIFEST.MF metadata inside Java archives; different format and purpose.
Programs that open WEBMANIFEST files
Windows4 apps
Visual Studio Code
Free Open the .webmanifest file to view and edit its JSON with syntax highlighting and JSON validation. 
Google Chrome (DevTools)
Free Load the PWA and use DevTools > Application > Manifest to parse and preview the manifest and its icons. 
macOS3 apps
Linux3 apps
PWA Manifest Generator (Progressier)
Freemium Create or edit a manifest in the browser and export a ready-to-use .webmanifest file. Technical details
deep spec| Encoding | UTF-8 text |
| Byte order | Not applicable (text) |
| Container | JSON object with top-level keys called members |
| Compression | None (may be gzip/brotli compressed in transit by the web server) |
| Typical size | Under 5 KB |
| Structure | A single JSON object whose members describe a web application: name, short_name, description, icons (array of image objects with src, sizes, type), start_url, scope, display, orientation, background_color, theme_color, categories, screenshots, shortcuts, share_target, protocol_handlers, and file_handlers. |
| Integrity | None built in; integrity relies on HTTPS transport and same-origin/CORS fetch rules |
| Platforms | Windows, macOS, Linux, Android, iOS, ChromeOS |
| Notes | Referenced from a page's HTML head via <link rel="manifest" href="app.webmanifest">. The browser reads it to install a Progressive Web App, set the home-screen icon and name, and control the launch display mode. Servers should return it with the application/manifest+json media type, though browsers also accept application/json. When the manifest is on a different origin than the page scope it must be fetched with CORS. |
| Released | 2013 (first W3C Working Draft, December 17, 2013) |
| Latest version | W3C Working Draft (ongoing) |
| Open standard | Yes · royalty-free |
| Specification | www.w3.org |
WEBMANIFEST conversions
Community Q&A
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