chrome.permissions

Description

Use the chrome.permissions API to request declared optional permissions at run time rather than install time, so users understand why the permissions are needed and grant only those that are necessary.

Overview

Permission warnings exist to describe the capabilities granted by an API, but some of these warnings may not be obvious. The Permissions API allows developers to explain permission warnings and introduce new features gradually which gives users a risk-free introduction to the extension. This way, users can specify how much access they are willing to grant and which features they want to enable.

For example, the optional permissions extension's core functionality is overriding the new tab page. One feature is displaying the user's goal of the day. This feature only requires the storage permission, which does not include a warning. The extension has an additional feature, that users can enable by clicking the following button:

Extension button that enables additional features

Displaying the user's top sites requires the topSites permission, which has the following warning.

Extension warning for topSites API

Implementing optional permissions

Step 1: Decide which permissions are required and which are optional

An extension can declare both required and optional permissions. In general, you should:

  • Use required permissions when they are needed for your extension's basic functionality.
  • Use optional permissions when they are needed for optional features in your extension.

Advantages of required permissions:

  • Fewer prompts: An extension can prompt the user once to accept all permissions.
  • Simpler development: Required permissions are guaranteed to be present.

Advantages of optional permissions:

  • Better security: Extensions run with fewer permissions since users only enable permissions that are needed.
  • Better information for users: An extension can explain why it needs a particular permission when the user enables the relevant feature.
  • Easier upgrades: When you upgrade your extension, Chrome will not disable it for your users if the upgrade adds optional rather than required permissions.

Step 2: Declare optional permissions in the manifest

Declare optional permissions in your extension manifest with the optional_permissions key, using the same format as the permissions field:

{
  "name": "My extension",
  ...
  "optional_permissions": ["tabs"],
  "optional_host_permissions": ["https://www.google.com/"],
  ...
}

If you want to request hosts that you only discover at runtime, include "https://*/*" in your extension's optional_host_permissions field. This lets you specify any origin in Permissions.origins as long as it has a matching scheme.

Permissions that can not be specified as optional

Most Chrome extension permissions can be specified as optional, with the following exceptions.

Permission Description
"debugger" The chrome.debugger API serves as an alternate transport for Chrome's remote debugging protocol.
"declarativeNetRequest" Grants the extension access to the chrome.declarativeNetRequest API.
"devtools" Allows extension to expand Chrome DevTools functionality.
"experimental" Canary and Dev channel only. Grants the extension access to chrome.experimental APIs.
"geolocation" Allows the extension to use the HTML5 geolocation API.
"mdns" Grants the extension access to the chrome.mdns API.
"proxy" Grants the extension access to the chrome.proxy API to manage Chrome's proxy settings.
"tts" The chrome.tts API plays synthesized text-to-speech (TTS).
"ttsEngine" The chrome.ttsEngine API implements a text-to-speech (TTS) engine using an extension.
"wallpaper" ChromeOS only. Use the chrome.wallpaper API change the ChromeOS wallpaper.

View Declare Permissions and Warn Users for further information on available permissions and their warnings.

Step 3: Request optional permissions

Request the permissions from within a user gesture using permissions.request():

document.querySelector('#my-button').addEventListener('click', (event) => {
  // Permissions must be requested from inside a user gesture, like a button's
  // click handler.
  chrome.permissions.request({
    permissions: ['tabs'],
    origins: ['https://www.google.com/']
  }, (granted) => {
    // The callback argument will be true if the user granted the permissions.
    if (granted) {
      doSomething();
    } else {
      doSomethingElse();
    }
  });
});

Chrome prompts the user if adding the permissions results in different warning messages than the user has already seen and accepted. For example, the previous code might result in a prompt like this:

example permission confirmation prompt

Step 4: Check the extension's current permissions

To check whether your extension has a specific permission or set of permissions, use permission.contains():

chrome.permissions.contains({
  permissions: ['tabs'],
  origins: ['https://www.google.com/']
}, (result) => {
  if (result) {
    // The extension has the permissions.
  } else {
    // The extension doesn't have the permissions.
  }
});

Step 5: Remove the permissions

You should remove permissions when you no longer need them. After a permission has been removed, calling permissions.request() usually adds the permission back without prompting the user.

chrome.permissions.remove({
  permissions: ['tabs'],
  origins: ['https://www.google.com/']
}, (removed) => {
  if (removed) {
    // The permissions have been removed.
  } else {
    // The permissions have not been removed (e.g., you tried to remove
    // required permissions).
  }
});

Types

Permissions

Properties

  • origins

    string[] optional

    The list of host permissions, including those specified in the optional_permissions or permissions keys in the manifest, and those associated with Content Scripts.

  • permissions

    string[] optional

    List of named permissions (does not include hosts or origins).

Methods

contains()

Promise 
chrome.permissions.contains(
  permissions: Permissions,
  callback?: function,
)

Checks if the extension has the specified permissions.

Parameters

  • permissions

    Permissions

  • callback

    function optional

    The callback parameter looks like: 

    (result: boolean) => void

    • result

      boolean

      True if the extension has the specified permissions. If an origin is specified as both an optional permission and a content script match pattern, this will return false unless both permissions are granted.

Returns

  • Promise<boolean>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

getAll()

Promise 
chrome.permissions.getAll(
  callback?: function,
)

Gets the extension's current set of permissions.

Parameters

  • callback

    function optional

    The callback parameter looks like: 

    (permissions: Permissions) => void

    • permissions

      Permissions

      The extension's active permissions. Note that the origins property will contain granted origins from those specified in the permissions and optional_permissions keys in the manifest and those associated with Content Scripts.

Returns

  • Promise<Permissions>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

remove()

Promise 
chrome.permissions.remove(
  permissions: Permissions,
  callback?: function,
)

Removes access to the specified permissions. If there are any problems removing the permissions, runtime.lastError will be set.

Parameters

  • permissions

    Permissions

  • callback

    function optional

    The callback parameter looks like: 

    (removed: boolean) => void

    • removed

      boolean

      True if the permissions were removed.

Returns

  • Promise<boolean>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

request()

Promise 
chrome.permissions.request(
  permissions: Permissions,
  callback?: function,
)

Requests access to the specified permissions, displaying a prompt to the user if necessary. These permissions must either be defined in the optional_permissions field of the manifest or be required permissions that were withheld by the user. Paths on origin patterns will be ignored. You can request subsets of optional origin permissions; for example, if you specify *://*\/* in the optional_permissions section of the manifest, you can request http://example.com/. If there are any problems requesting the permissions, runtime.lastError will be set.

Parameters

  • permissions

    Permissions

  • callback

    function optional

    The callback parameter looks like: 

    (granted: boolean) => void

    • granted

      boolean

      True if the user granted the specified permissions.

Returns

  • Promise<boolean>

    Chrome 96+

    Promises are only supported for Manifest V3 and later, other platforms need to use callbacks.

Events

onAdded

chrome.permissions.onAdded.addListener(
  callback: function,
)

Fired when the extension acquires new permissions.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (permissions: Permissions) => void

onRemoved

chrome.permissions.onRemoved.addListener(
  callback: function,
)

Fired when access to permissions has been removed from the extension.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (permissions: Permissions) => void