manifest.json

This article describes manifest.json for web extensions. If you are looking for information about the manifest.json in PWAs, check out the Web App Manifest article.

The manifest.json file is the only file that every extension using WebExtension APIs must contain.

Using manifest.json, you specify basic metadata about your extension such as the name and version, and can also specify aspects of your extension's functionality, such as background scripts, content scripts, and browser actions.

It is a JSON-formatted file, with one exception: it is allowed to contain "//"-style comments.

manifest.json keys are listed below:

"manifest_version", "version", and "name" are the only mandatory keys. "default_locale" must be present if the "_locales" directory is present and must be absent otherwise. "browser_specific_settings" is not supported in Google Chrome.

You can access your extension's manifest from the extension's JavaScript using the runtime.getManifest() function:

browser.runtime.getManifest().version;

Example

The block below contains shows the basic syntax for some common manifest keys. Note that it is not intended to be used as a copy-paste-ready example: which keys you need will depend on the extension you are developing. For complete example extensions, see Example extensions.

{
  "browser_specific_settings": {
    "gecko": {
      "id": "addon@example.com",
      "strict_min_version": "42.0"
    }
  },

  "background": {
    "scripts": ["jquery.js", "my-background.js"],
    "page": "my-background.html"
  },

  "browser_action": {
    "default_icon": {
      "19": "button/geo-19.png",
      "38": "button/geo-38.png"
    },
    "default_title": "Whereami?",
    "default_popup": "popup/geo.html"
  },

  "commands": {
    "toggle-feature": {
      "suggested_key": {
        "default": "Ctrl+Shift+Y",
        "linux": "Ctrl+Shift+U"
      },
      "description": "Send a 'toggle-feature' event"
    }
  },

  "content_security_policy": "script-src 'self' https://example.com; object-src 'self'",

  "content_scripts": [
    {
      "exclude_matches": ["*://developer.mozilla.org/*"],
      "matches": ["*://*.mozilla.org/*"],
      "js": ["borderify.js"]
    }
  ],

  "default_locale": "en",

  "description": "...",

  "icons": {
    "48": "icon.png",
    "96": "icon@2x.png"
  },

  "manifest_version": 2,

  "name": "...",

  "page_action": {
    "default_icon": {
      "19": "button/geo-19.png",
      "38": "button/geo-38.png"
    },
    "default_title": "Whereami?",
    "default_popup": "popup/geo.html"
  },

  "permissions": ["webNavigation"],

  "version": "0.1",

  "user_scripts": {
    "api_script": "apiscript.js",
  },

  "web_accessible_resources": ["images/my-image.png"]
}

Browser compatibility

BCD tables only load in the browser

For a full overview of all manifest keys and their sub-keys, see the full manifest.json browser compatibility table.

See also

permissions JavaScript API