Mullvad Browser Extension

Mullvad Browser Extension is a Firefox extension improving your browser experience while using Mullvad VPN. It also displays information about the connection, recommends optimal DNS settings, and a one-click access to proxy servers.

Download

You can visit our download page to get the latest release.

The extension is also available here on Github in the Releases.

Development

Environment

Build with:

• Node 20.11.0
• Npm 10.2.4

If you use nvm, run nvm use to automatically set these versions.

For:

• Firefox: last version (>91.1.0)

Developing

The first time, use npm install to install the necessary packages.

To start the extension in a a temporary and clean browser:

• use npm run dev to automatically rebuild the extension when changes are saved.
• use npm start in another terminal to start a development instance of Firefox with the extension loaded. The extension will automatically reload when changes are saved.

The developer tools can be started by clicking on the inspect in the debugging tab (automatically opened).

Building

• use npm run build to build the extension first
• use npm run pack:xpi to create .xpi file in the root folder

There are other build options which you can view in package.json.

Testing the extension in your browser

You can only install the extension temporarily when it is not signed by Mozilla. To do so:

• open Firefox
• enter "about:debugging#/runtime/this-firefox" in the URL bar
• click "Load Temporary Add-on"
• open extension.xpi file.

The extension will automatically unload when Firefox is closed.

Testing restart and persisting features

You can use the restart script to test restart and persisting features (like settings saved to local storage). It will require some manual configuration:

• go to about:profiles and create a new Firefox profile
• go to package.json and change the restart script with your own Firefox profile path
• go to about:config and set both extensions.webextensions.keepStorageOnUninstall and extensions.webextensions.keepUuidOnUninstall to true.

Learn more

Permissions

Mullvad Browser Extension requires the following permissions:

• management to be able to recommend third party extensions
• privacy to disable webRTC and check HTTPS-Only status
• storage to save preferences
• search to recommend other search engines
• *://*.mullvad.net/* to get proxy servers list and display your connection information (See Network requests for details)

The following permissions are optional, but are needed to use the proxy feature:

• proxy to configure and use Mullvad proxy servers
• tabs to show proxy settings from active tab
• <all_urls> to specify a proxy configuration per domain (each request needs to be intercepted)

Permissions are automatically accepted when testing the extension.

Network requests

Two external network requests are made by the extension:

• api.mullvad.net to get the lastest proxy servers (Frequency: each time the Select proxy server location drawer is opened)
• am.i.mullvad.net to get the connection information (Frequency: each time the popup is started and each time the proxy is connected/disconnected)

External links are marked with this icon

Source code

Source code is available in the Github repo.