browser_specific_settings

The browser_specific_settings key contains keys that are specific to a particular host application.

Firefox stores browser-specific settings in these sub-keys:

• gecko for the desktop version of Firefox.
• gecko_android for the Android version of Firefox.

The gecko subkey supports these properties:

id

The extension ID. When provided, this property must contain 80 characters or less. See Extensions and the Add-on ID to determine when to specify the ID.

strict_min_version

Minimum version of Gecko to support. If the Firefox version on which the extension is being installed or run is below this version, the extension is not installed or not run. If not provided, all versions earlier than strict_max_version are supported. "*" is not valid in this field.

strict_max_version

Maximum version of Gecko to support. If the Firefox version on which the extension is being installed or run is above this version, the extension is not installed or not run. Defaults to "*", which disables checking for a maximum version.

update_url

A link to an extension update manifest. Note that the link must begin with "https". This key is for managing extension updates yourself (i.e., not through AMO).

The gecko_android subkey supports these properties:

strict_min_version

Minimum version of Gecko to support on Android. If the Firefox for Android version on which the extension is being installed or run is below this version, the extension is not installed or not run. If not provided, defaults to the version determined by gecko.strict_min_version. "*" is not valid in this field.

strict_max_version

Maximum version of Gecko to support on Android. If the Firefox version on which the extension is being installed or run is above this version, the extension is not installed or not run. Defaults to the version determined by gecko.strict_max_version.

See the list of valid Gecko versions.

To support Firefox for Android without specifying a version range, the gecko_android subkey must be an empty object, i.e. "gecko_android": {}. Otherwise, the extension is only made available on desktop Firefox.

Extension ID format

The extension ID must be one of the following:

• GUID
• A string formatted like an email address: extensionname@example.org

The latter format is easier to generate and manipulate. Be aware that using a real email address here may attract spam.

For example:

"id": "extensionname@example.org"

"id": "{daf44bf7-a45e-4450-979c-91cf07434c3d}"

Safari stores its browser-specific settings in the safari subkey, which has these properties:

strict_min_version

Minimum version of Safari to support.

strict_max_version

Maximum version of Safari to support.

Example with all possible keys. Note that most extensions omit strict_max_version and update_url.

"browser_specific_settings": {
  "gecko": {
    "id": "addon@example.com",
    "strict_min_version": "42.0",
    "strict_max_version": "50.*",
    "update_url": "https://example.com/updates.json"
  },
  "safari": {
    "strict_min_version": "14",
    "strict_max_version": "20"
  }
}