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
    </a>
  </div>

• Using JavaScript, like this:

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

  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.

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.