protonvpn servers can be used with openvpn
You can use your proton credentials to connect to a Proton VPN server using a third-party, open source VPN app, like Tunnelblick for macOS or OpenVPN for GNU/Linux.
Learn how to sign in to Proton VPN with third-party VPN applications.
These credentials cannot be used to sign in to our official Proton VPN apps.