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Firefox Private Mode

You cannot run add-ons in Firefox Private Mode using the normal side-loading technique. This is because only they appear in the about:debugging page, which doesn’t give you the option to enable the extension in Private Mode.

As an alternative, you can install the development build as an unsigned add-on using the steps below.


  1. Install Firefox Developer Edition

  2. Configure Firefox Developer Edition:

    1. Open Firefox Developer Edition
    2. Navigate to about:config
    3. Set the xpinstall.signatures.required setting to false (add the setting if it’s not in the list already)


  1. Open your local browser repository on the command line
  2. Build and package the browser extension with npm run dist:firefox
  3. Open Firefox Developer Edition and navigate to about:addons
  4. Click the cog in the top-right next to “Manage Your Extensions”
  5. Click “Install Add-on From File”
  6. Open dist/ in your local repository
  7. The extension will now be the about:addons page. Click on the name of the extension to expand it, and then toggle “Run in Private Windows”.