WEBMANIFEST MIME Type

About Web app manifest files

The manifest linked with <link rel="manifest"> gives an installable web app its name, icons, colours and start URL. Browsers also accept it as application/json or with a .json extension, so the type rarely causes problems; a wrong icon path or missing icon size is the more common reason an app isn’t installable.

File signature

WEBMANIFEST has no fixed signature: it is data without a magic number, so validate uploads by parsing the content rather than by checking bytes.

Serve .webmanifest with the right Content-Type

Content-Type: application/manifest+json

application/manifest+json webmanifest;

AddType application/manifest+json .webmanifest

@webmanifest path *.webmanifest
header @webmanifest Content-Type "application/manifest+json"

curl -sI https://example.com/file.webmanifest | grep -i '^content-type'
# Content-Type: application/manifest+json

Set the type in code

res.set('Content-Type', 'application/manifest+json');

import mimetypes

mimetypes.add_type('application/manifest+json', '.webmanifest')  # if your system doesn't know it
mimetypes.guess_type('file.webmanifest')[0]  # 'application/manifest+json'

mime.AddExtensionType(".webmanifest", "application/manifest+json")
w.Header().Set("Content-Type", "application/manifest+json")

Accept .webmanifest uploads

<input type="file" accept=".webmanifest,application/manifest+json">

The accept attribute only filters the file picker; users can still choose another file. Listing the extension as well as the type matters, because operating systems don’t always report the type you expect.

Related types

• .json (application/json): JSON
• .png (image/png): PNG image
• .html (text/html): HTML

More web

.css , .js , .mjs , .svg , .wasm , .rss , .vtt . Look up any extension or type with the MIME type lookup.

Sources

• IANA registration: application/manifest+json
• MDN: Common media types

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Frequently asked questions