Proton Mail is an email and security service by Proton AG, based in Switzerland. Founded in 2014 by CERN scientists, it offers end-to-end encrypted email, calendar and file storage designed to keep user data private. Proton Mail’s infrastructure is hosted under Swiss privacy laws (no data goes to the US), and the company has grown to over 100 million users worldwide. The service is open-source and ad-free, with a commitment that even Proton cannot read customer data (zero-access encryption).