Type Array
Mandatory No
Manifest version 2 or higher
"optional_permissions": [

Use the optional_permissions key to list permissions that you want to ask for at runtime, after your extension has been installed.

The permissions key lists permissions that your extension needs before it can be installed. In contrast, optional_permissions lists permissions that your extension doesn't need at install time but it may ask for after it has been installed. To ask for a permission, use the permissions API. Asking for a permission may present the user with a dialog requesting them to grant the permission to your extension.

For advice on designing your request for runtime permissions, to maximize the likelihood that users grant them, see Request permissions at runtime.

Starting with Firefox 84, users can manage optional permissions from the Firefox Add-ons Manager. Extensions that use optional permissions can listen for browser.permissions.onAdded and browser.permissions.onRemoved API events to know when a user grants or revokes these permissions.

The key can contain two kinds of permissions: host permissions and API permissions.

Host permissions

These are the same as the host permissions you can specify in the permissions key.

Note: When using Manifest V3 or higher optional host permissions should be specified using the optional_host_permission manifest key. Firefox introduced optional_host_permissionin release 128, see bug 1766026, and allows for the continued use of optional_permissions to specify optional hosts. Use of optional_host_permission however is recommended.

API permissions

You can include any of the following here, but not in all browsers: check the compatibility table for browser-specific details.

  • activeTab
  • background
  • bookmarks
  • browserSettings
  • browsingData
  • clipboardRead
  • clipboardWrite
  • contentSettings
  • contextMenus
  • cookies
  • debugger
  • declarativeNetRequest
  • declarativeNetRequestFeedback
  • declarativeNetRequestWithHostAccess
  • devtools
  • downloads
  • downloads.open
  • find
  • geolocation
  • history
  • idle
  • management
  • nativeMessaging
  • notifications
  • pageCapture
  • pkcs11
  • privacy
  • proxy
  • scripting
  • search
  • sessions
  • tabHide
  • tabs
  • topSites
  • webNavigation
  • webRequest
  • webRequestBlocking
  • webRequestFilterResponse
  • webRequestFilterResponse.serviceWorkerScript

Note that this is a subset of the API permissions allowed in permissions.

Of this set, the following permissions are granted silently, without a user prompt:

  • activeTab
  • cookies
  • idle
  • webRequest
  • webRequestBlocking
  • webRequestFilterResponse
  • webRequestFilterResponse.serviceWorkerScript


 "optional_permissions": ["*://developer.mozilla.org/*"]

In Manifest V2 only, enable the extension to ask for privileged access to pages under developer.mozilla.org.

  "optional_permissions": ["tabs"]

Enable the extension to ask for access to the privileged pieces of the tabs API.

  "optional_permissions": ["*://developer.mozilla.org/*", "tabs"]

In Manifest V2 only, enable the extension to ask for both of the above permissions.

Browser compatibility

BCD tables only load in the browser