Type Array
Mandatory No
Example
"permissions": [
  "*://developer.mozilla.org/*",
  "webRequest"
]

Use the permissions key to request special powers for your extension. This key is an array of strings, and each string is a request for a permission.

If you request permissions using this key, then the browser may inform the user at install time that the extension is requesting certain privileges, and ask them to confirm that they are happy to grant these privileges. The browser may also allow the user to inspect an extension's privileges after installation.

The key can contain three kinds of permissions:

  • host permissions
  • API permissions
  • the activeTab permission

Host permissions

Host permissions are specified as match patterns, and each pattern identifies a group of URLs for which the extension is requesting extra privileges. For example, a host permission could be "*://developer.mozilla.org/*".

The extra privileges include:

  • XMLHttpRequest and fetch access to those origins without cross-origin restrictions (even for requests made from content scripts)
  • the ability to inject scripts programmatically (using tabs.executeScript) into pages served from those origins
  • the ability to receive events from the webRequest API for these hosts
  • the ability to access cookies for that host using the cookies API, as long as the "cookies" API permission is also included.
  • bypass tracking protection if the host is a full domain without wildcards. Doesn't work with <all_urls>.

In Firefox, from version 56 onwards, extensions automatically get host permissions for their own origin, which is of the form:

moz-extension://60a20a9b-1ad4-af49-9b6c-c64c98c37920/

where 60a20a9b-1ad4-af49-9b6c-c64c98c37920 is the extension's internal ID. The extension can get this URL programmatically by calling extension.getURL():

browser.extension.getURL("");
// moz-extension://60a20a9b-1ad4-af49-9b6c-c64c98c37920/

API permissions

API permissions are specified as keywords, and each keyword names a WebExtension API that the extension would like to use.

The following keywords are currently available:

  • activeTab
  • alarms
  • background
  • bookmarks
  • browserSettings
  • browsingData
  • contentSettings
  • contextMenus
  • contextualIdentities
  • cookies
  • debugger
  • dns
  • downloads
  • downloads.open
  • find
  • geolocation
  • history
  • identity
  • idle
  • management
  • menus
  • nativeMessaging
  • notifications
  • pageCapture
  • pkcs11
  • privacy
  • proxy
  • search
  • sessions
  • storage
  • tabHide
  • tabs
  • theme
  • topSites
  • webNavigation
  • webRequest
  • webRequestBlocking

In most cases the permission just grants access to the API, with the following exceptions:

activeTab permission

This permission is specified as "activeTab". If an extension has the activeTab permission, then when the user interacts with the extension, the extension is granted extra privileges for the active tab only.

"User interaction" includes:

  • the user clicks the extension's browser action or page action
  • the user selects its context menu item
  • the user activates a keyboard shortcut defined by the extension

The extra privileges are:

  • the ability to inject JavaScript or CSS into the tab programmatically, using browser.tabs.executeScript and browser.tabs.insertCSS
  • access to the privileged parts of the tabs API for the current tab: Tab.url, Tab.title, and Tab.faviconUrl.

The intention of this permission is to enable extensions to fulfill a common use case, without having to give them very powerful permissions. Many extensions want to "do something to the current page when the user asks". For example, consider an extension that wants to run a script in the current page when the user clicks a browser action. If the  activeTab permission did not exist, the extension would need to ask for the host permission <all_urls>. But this gives the extension more power than it needs: it could now execute scripts in any tab, any time it likes, instead of just the active tab and just in response to a user action.

Note that you can only get access to the tab/data that was there, when the user interaction occurred (e.g. the click). When the active tab navigates away, e.g. due to finishing loading or some other event, the permission does not grant you access to the tab anymore.

Usually the tab that's granted activeTab is just the currently active tab, except in one case. The menus API enables an extension to create a menu item which is shown if the user context-clicks on a tab (that is, on the element in the tabstrip that enables the user to switch from one tab to another). If the user clicks such an item, then the activeTab permission is granted for the tab the user clicked, even if that's not the currently active tab.

Clipboard access

There are two permissions which enables the extension to interact with the clipboard:

  • clipboardWrite: write to the clipboard using document.execCommand("copy") or document.execCommand("cut")
  • clipboardRead: read from the clipboard using document.execCommand("paste")

See Interact with the clipboard for all the details on this.

Unlimited storage

The unlimitedStorage permission:

  • enables extensions to exceed any quota imposed by the storage.local API
  • in Firefox, enables extensions to create a "persistent" IndexedDB database, without the browser prompting the user for permission at the time the database is created.

Example

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

Request privileged access to pages under developer.mozilla.org.

  "permissions": ["tabs"]

Request access to the privileged pieces of the tabs API.

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

Request both of the above permissions.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxOperaFirefox for Android
Basic supportChrome Full support YesEdge Full support 14Firefox Full support 48Opera Full support YesFirefox Android Full support 48
activeTabChrome Full support YesEdge No support NoFirefox Full support 48Opera Full support YesFirefox Android Full support 48
alarmsChrome Full support YesEdge No support NoFirefox Full support 45Opera Full support YesFirefox Android Full support 48
backgroundChrome Full support 10Edge No support NoFirefox No support NoOpera No support NoFirefox Android No support No
bookmarksChrome Full support YesEdge Full support 15Firefox Full support 45Opera Full support YesFirefox Android No support No
browserSettingsChrome No support NoEdge No support NoFirefox Full support 56Opera No support NoFirefox Android Full support 56
browsingDataChrome Full support YesEdge No support NoFirefox Full support 53Opera Full support YesFirefox Android Full support 56
clipboardReadChrome Full support YesEdge No support NoFirefox Full support 54Opera Full support YesFirefox Android Full support 54
clipboardWriteChrome Full support YesEdge No support NoFirefox Full support 51Opera Full support YesFirefox Android Full support 51
contentSettingsChrome Full support YesEdge No support NoFirefox No support NoOpera Full support YesFirefox Android No support No
contextMenusChrome Full support YesEdge Full support 14Firefox Full support 55
Notes
Full support 55
Notes
Notes Available as an alias to the menus permission.
Opera Full support YesFirefox Android No support No
contextualIdentitiesChrome No support NoEdge No support NoFirefox Full support 53Opera No support NoFirefox Android Full support 53
cookiesChrome Full support YesEdge Full support 14Firefox Full support 45Opera Full support YesFirefox Android Full support 48
debuggerChrome Full support YesEdge No support NoFirefox No support NoOpera Full support YesFirefox Android No support No
dnsChrome No support NoEdge No support NoFirefox Full support 60Opera No support NoFirefox Android Full support 60
downloadsChrome Full support YesEdge No support NoFirefox Full support 47Opera Full support YesFirefox Android Full support 48
downloads.openChrome Full support YesEdge No support NoFirefox Full support 48Opera Full support YesFirefox Android Full support 48
findChrome No support NoEdge No support NoFirefox Full support 57Opera No support NoFirefox Android No support No
geolocationChrome Full support YesEdge Full support 14Firefox Full support 54Opera Full support YesFirefox Android Full support 54
historyChrome Full support YesEdge No support NoFirefox Full support 49Opera Full support YesFirefox Android No support No
identityChrome Full support YesEdge No support NoFirefox Full support 53Opera Full support YesFirefox Android No support No
idleChrome Full support YesEdge Full support 15Firefox Full support 45Opera Full support YesFirefox Android Full support 48
managementChrome Full support YesEdge No support NoFirefox Full support 51Opera Full support YesFirefox Android Full support 51
menusChrome No support NoEdge No support NoFirefox Full support 53Opera No support NoFirefox Android No support No
nativeMessagingChrome Full support 29Edge Full support 15Firefox Full support 50Opera Full support 16Firefox Android No support No
notificationsChrome Full support 5Edge No support NoFirefox Full support 45Opera Full support 25Firefox Android Full support 48
pageCaptureChrome Full support YesEdge No support NoFirefox No support NoOpera Full support YesFirefox Android No support No
pkcs11Chrome No support NoEdge No support NoFirefox Full support 58Opera No support NoFirefox Android No support No
privacyChrome Full support YesEdge No support NoFirefox Full support 54Opera Full support YesFirefox Android Full support 54
proxyChrome No support NoEdge No support NoFirefox Full support 55Opera No support NoFirefox Android Full support 55
sessionsChrome Full support YesEdge No support NoFirefox Full support 52Opera Full support YesFirefox Android No support No
storageChrome Full support YesEdge Full support 14Firefox Full support 45Opera Full support YesFirefox Android Full support 48
tabsChrome Full support YesEdge Full support 14Firefox Full support 45Opera Full support YesFirefox Android Full support 54
themeChrome No support NoEdge No support NoFirefox Full support 55Opera No support NoFirefox Android No support No
topSitesChrome Full support YesEdge No support NoFirefox Full support 52Opera Full support YesFirefox Android Full support 52
unlimitedStorageChrome Full support YesEdge Full support 14Firefox Full support 56Opera No support NoFirefox Android Full support 56
webNavigationChrome Full support YesEdge Full support 14Firefox Full support 45Opera Full support 17Firefox Android Full support 48
webRequestChrome Full support YesEdge Full support 14Firefox Full support 45Opera Full support YesFirefox Android Full support 48
webRequestBlockingChrome Full support YesEdge Full support 14Firefox Full support 45Opera Full support YesFirefox Android Full support 48

Legend

Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.

Document Tags and Contributors

Last updated by: hellosct1,