Editor’s note: This article is the third in a series focusing on the best encrypted apps and services available. Content has been provided by an anonymous security and privacy professional. Readers are encouraged to verify this information on their own.


ProtonMail was founded by CERN and MIT scientists after the Snowden leak. Their goal was to create an encrypted email service that is just as easy to use as an unencrypted one. ProtonMail is partly open source, with the browser-based JavaScript encryption being accessible simply by using a browser’s “view source” tool. It was originally audited by CERN’s computer security staff, and later by outside professionals donating their time, who also got access to the back-end code. ProtonMail has been attempting to become completely open source for a long time (unedited code would not be flattering), but resources are limited. However, they do maintain an open source library.

ProtonMail gives free accounts an address and 500mb of storage, with additional storage, alias addresses, and other features purchasable piecemeal or bundled. Paid users can also download emails to an IMAP and/or SMTP-supporting application, via the ProtonMail Bridge application. ProtonMail is based in Switzerland. (one of the perks of working at CERN, along with the lunchroom being a captive audience of top engineers. Though they once drew criticism for sharing metadata with law enforcement in a kidnapping case in which a court order was inevitable but had not yet been issued.) Timers for ephemeral emails are set in hourly increments, with the longest delay being four weeks, set using drop-down menus for weeks, days, and hours. Out of network encrypted email can only be ephemeral (that is, they become impossible to decrypt), defaulting to four weeks—I don’t know what’s the purpose, but it hasn’t caused any problems.