Analysis of information sources in references of the Wikipedia article "Proton AG" in Portuguese language version.
We don't plan to open source the back-end code, because it doesn't add trust (users can't verify what code is running on the backend) and doing so would given away information about how we do anti-spam and anti-abuse.
We don't have a stand-alone back-end that can be installed for small deployment, because our backend software is optimized for large deployments with millions of users and distributed infrastructure.
