Current availability
BadAssProxy does not currently publish its own Firefox add-on. Firefox provides manual connection settings, and extensions can manage proxy settings. Check the supported authentication method for your particular proxy and client.
Configure and test
Find Proxy settings in Firefox Settings, open the connection configuration and enter the supplied host and port for the appropriate protocol. Use the official Mozilla guide for your Firefox version. Test the connection before starting your workflow.
Keep a reversible setup
Record the original network settings before making changes. If connectivity fails, restore those settings and check the proxy credentials and product status. Only install add-ons from publishers you trust.