Proton Mail

Proton Mail is an end-to-end encryptedemail hosting service. It was launched in 2014 by Andy Yen, Jason Stockman and Wei Sun. Proton Mail is headquartered in Geneva, Switzerland. It is owned by the non-profit Proton Foundation through its subsidiary Proton AG, which also operates Proton VPN, Proton Drive, Proton Calendar, Proton Pass, Proton Wallet, Proton Meet, and Lumo AI. Proton Mail uses client-side encryption to protect email content and user data before they are sent to company servers, unlike other common email providers such as Gmail and Outlook.com.

Proton Mail received its initial funding through a crowdfunding campaign, and initial access was by invitation only, but it opened to the public in 2016. There were two million users by 2017, almost 70 million by 2022, and 100 million users in 2024.

The source code for the back end of Proton Mail remains closed-source, but Proton Mail released the source code for the web interface, iOS and Android apps, and the Proton Mail Bridge app under an open-source licence.