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Phone showing several notification badges

Badging for app icons

The Badging API allows installed web apps to set an application-wide badge on the app icon.

Updated
Pete LePage
Pete LePage

Caution: This API is part of the new capabilities project, and it is available as an origin trial. This post will be updated as the Badging API evolves.

What is the Badging API?

Example of Twitter with eight notifications and another app showing a flag type badge.
Example of Twitter with eight notifications and another app showing a flag type badge.

The Badging API allows installed web apps to set an application-wide badge, shown in an operating-system-specific place associated with the application (such as the shelf or home screen).

Badging makes it easy to subtly notify the user that there is some new activity that might require their attention, or to indicate a small amount of information, such as an unread count.

Badges tend to be more user-friendly than notifications, and can be updated with a much higher frequency, since they don't interrupt the user. And, because they don't interrupt the user, they don't need the user's permission.

Possible use cases

Examples of sites that may use this API include:

  • Chat, email, and social apps, to signal that new messages have arrived, or to show the number of unread items.
  • Productivity apps, to signal that a long-running background task (such as rendering an image or video) has completed.
  • Games, to signal that a player action is required (e.g., in Chess, when it is the player's turn).

Current status

Step Status
1. Create explainer Complete
2. Create initial draft of specification Complete
3. Gather feedback & iterate on design In progress
4. Origin trial v2 (Chrome 79-81) In progress
v1 (Chrome 73-78) In progress
5. Launch Not started

Try it

  1. Using Chrome 73 or later on Windows or Mac, open the Badging API demo.
  2. When prompted, click Install to install the app, or use the Chrome menu to install it.
  3. Open it as an installed PWA. Note, it must be running as an installed PWA (in your task bar or dock).
  4. Click the Set or Clear button to set or clear the badge from the app icon. You can also provide a number for the Badge value.

How to use the Badging API

The Badging API is available as an origin trial in Chrome 79 and later.

The Badging API works on Windows, and macOS. Support for Chrome OS is in development and will be available in a future release of Chrome. On Android, the Badging API is not supported. Instead, Android automatically shows a badge on a web app when there is an unread notification, just like for native apps.

Register for the origin trial

Caution: In Chrome 79 (stable Dec 2019), the first origin trial ended, and was replaced by a new origin trial that uses a slightly different API design. Unfortunately, it is not backwards compatible, and calls to the previous API will fail. See Supporting both the first and second origin trial for details on how to provide backwards compatibility.

Origin trials allow you to try new features and give feedback on their usability, practicality, and effectiveness to the web standards community. For more information, see the Origin Trials Guide for Web Developers. To sign up for this or another origin trial, visit the registration page.

  1. Request a token for your origin.
  2. Add the token to your pages. There are two ways to do that:
    • Add an origin-trial <meta> tag to the head of each page. For example, this may look something like:
      <meta http-equiv="origin-trial" content="TOKEN_GOES_HERE">
    • If you can configure your server, you can also add the token using an Origin-Trial HTTP header. The resulting response header should look something like:
      Origin-Trial: TOKEN_GOES_HERE

If necessary, you can request a token for Chrome 78 and earlier.

Alternatives to the origin trial

If you want to experiment with the Badging API locally, without an origin trial, enable the #enable-experimental-web-platform-features flag in chrome://flags.

Setting and clearing a badge

To use the Badging API, your web app needs to meet Chrome's installability criteria, and users must add it to their home screens.

The Badge API consists of the following methods on navigator:

  • setExperimentalAppBadge([number]): Sets the app's badge. If a value is provided, set the badge to the provided value otherwise, display a plain white dot (or other flag as appropriate to the platform).
  • clearExperimentalAppBadge(): Removes app's badge.

For example:

// Set the badge
const unreadCount = 24;
navigator.setExperimentalAppBadge(unreadCount);

// Clear the badge
navigator.clearExperimentalAppBadge();

setExperimentalAppBadge() and clearExperimentalAppBadge() can be called from a foreground page, or potentially in the future, a service worker. In either case, it affects the whole app, not just the current page.

In some cases, the OS may not allow the exact representation of the badge. In such cases, the browser will attempt to provide the best representation for that device. For example, because the Badging API isn't supported on Android, Android only ever shows a dot instead of a numeric value.

Don't assume anything about how the user agent wants to display the badge. Some user agents may take a number like "4000" and rewrite it as "99+". If you saturate the badge yourself (for example by setting it to "99") then the "+" won't appear. No matter the actual number, just call setExperimentalAppBadge(unreadCount) and let the user agent deal with displaying it accordingly.

While the Badging API in Chrome requires an installed app, you shouldn't make calls to the Badging API dependent on the install state. Just call the API when it exists, as other browsers may show the badge in other places. If it works, it works. If not, it simply doesn't.

Supporting both the first and second origin trial

In Chrome 79, a second origin trial was started. Based on developer feedback recevied during the first origin trial, the API has changed, and is not backwards compatible with the first origin trial.

If you have an existing implementation, and want to provide backwards compatibility for your users, you can wrap the calls in the following wrapper function. Once all of your users have migrated to Chrome 79 or later, you can remove this wrapper function from your code.

function setBadge(...args) {
if (navigator.setExperimentalAppBadge) {
navigator.setExperimentalAppBadge(...args);
} else if (window.ExperimentalBadge) {
window.ExperimentalBadge.set(...args);
}
}

function clearBadge() {
if (navigator.clearExperimentalAppBadge) {
navigator.clearExperimentalAppBadge();
} else if (window.ExperimentalBadge) {
window.ExperimentalBadge.clear();
}
}

Be sure to include both the first (Chrome 78 and earlier), and second (Chrome 79 and later) origin trial tokens in your page.

Feedback

The Chrome team wants to hear about your experiences with the Badging API.

Tell us about the API design

Is there something about the API that doesn't work like you expected? Or are there missing methods or properties that you need to implement your idea? Have a question or comment on the security model?

Report a problem with the implementation

Did you find a bug with Chrome's implementation? Or is the implementation different from the spec?

  • File a bug at https://new.crbug.com. Be sure to include as much detail as you can, simple instructions for reproducing, and set Components to UI>Browser>WebAppInstalls. Glitch works great for sharing quick and easy repros.

Show support for the API

Planning to use Badging API on your site? Your public support helps the Chrome team to prioritize features, and shows other browser vendors how critical it is to support them.

  • Send a Tweet to @ChromiumDev tagged with #badgingapi and let us know where and how you're using it.

Helpful links

Last updated: Improve article