Distributing an add-on yourself

You aren't required to list or distribute your add-on through addons.mozilla.org (AMO); you can distribute it yourself. However, before distributing your add-on yourself, here are some things you should consider:

  • AMO is a very popular distribution platform, with millions of monthly visitors and installations. It's integrated into the Firefox Add-ons Manager, allowing for easy installation of add-ons published on AMO.

  • When an add-on is listed on AMO, Firefox automatically updates installed copies when a new version is listed on AMO. To enable Firefox to automatically update self-distributed add-ons, you need to include the URL where Firefox can find updates in the add-on manifest's update_url key. If the add-on does not have an update URL to check, Firefox will check AMO for a listed update. If a listed update with a higher version number is available, Firefox will distribute that version to users who have installed the self-distributed file.

For more information on how to submit an add-on for distribution on AMO or self-distribution, see Submitting an add-on.

Self-distribution options

When you choose to distribute an add-on yourself, they can be installed using the following methods:

  • Web download—make your extension available on a suitable web accessible server and when the user downloads the signed add-on file Firefox installs it. The web accessible server must serve the signed addon xpi file with Content-Type: application/x-xpinstall in the HTTP response headers.
  • Installing add-on from file—enables a user to install an add-on using an .xpi file saved on their computer.
  • Add-ons for use with a desktop app—starting with Firefox 74, it is no longer be possible to have an extension be automatically installed as part of another application install. See the Add-ons Blog for more information.
  • Add-ons in an enterprise environment—this page discusses the use of signed compared to unsigned extensions, installation options, the Firefox settings affecting installation, and including add-ons with a custom Firefox install package.

Web download

When distributing an add–on from your website, you have two options for making the signed add–on file available for download:

  • Recommended approach: from a link on a webpage, like this:

    <div id="example-option-1" class="install-ok">
      <a href="https://example.com/path/to/extension.xpi">
        Install my add-on
  • Using JavaScript, like this:

    <div id="example-option-2" class="install-ok">
        Install my add-on
        document.querySelector("#example-option-2 > button").onclick = () => {
          window.location = "https://example.com/path/to/extension.xpi";

    If you take this approach, make sure that the browser detects your JavaScript code as handling user input, for example, it is called from inside a DOM click event.

If the download link or triggering JavaScript is not on the top-level frame of the website, none of the frames between the top-level page and the frame containing the download or JavaScript can be third-party or cross-origin frames.

You may find references to using the InstallTrigger API to trigger a download from JavaScript. This API was never officially supported and will be removed from Firefox 102. Use is therefore not recommended.

Using either method, when the user downloads the signed add-on file Firefox installs it.

See submitting an add-on for details on how to download your signed add-on file.