Proton Mail

Proton Mail is a <a href="/facts/Switzerland/LcGuxeTe">Swiss</a> <a href="/facts/End-to-end_encryption/e1MwRzEU">end-to-end encrypted</a> <a href="/facts/Email/6pD9GLtI">email</a> service launched in 2014 and operated by <a href="/facts/Proton_AG/8XyLckH3">Proton AG</a>, which also operates <a href="/facts/Proton_VPN/euXoC16J">Proton VPN</a>, <a href="/facts/Proton_Drive/zkzPe5pX">Proton Drive</a>, <a href="/facts/Proton_Calendar/8XyLckH3">Proton Calendar</a>, <a href="/facts/Proton_Pass/mVLeD3c0">Proton Pass</a> and Proton Wallet. Proton AG is owned by the nonprofit Proton Foundation. Proton Mail uses <a href="/facts/Client-side_encryption/og8q1jQp">client-side encryption</a> to protect email content and user data before they are sent to Proton Mail servers, unlike other common email providers such as <a href="/facts/Gmail/GXU2IQH4">Gmail</a> and <a href="/facts/Outlook.com/I4sund79">Outlook.com</a>. 
Proton Mail received its initial funding through a <a href="/facts/Crowdfunding/u9gwrlYI">crowdfunding</a> campaign, and initial access was by invitation only, but it opened to the public in 2016. There were two million users by 2017 and almost 70 million by 2022.
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 <a href="/facts/Open-source_license/FlFTwHmd">open-source license</a>.

Proton Mail open-in-new

Proton Mail