The best open source Email Client alternative to Proton Mail is Tuta Mail. If that doesn't suit you, our users have ranked more than 100 alternatives to Proton Mail and eight of them are open source Email Clients so hopefully you can find a suitable replacement. Other interesting open source Email Client alternatives to Proton Mail are Posteo, Infomaniak kMail, Criptext and Swisscows.email.
Offers comprehensive encryption for email, calendar, and contacts with zero personal info required. Built on open source, install via Play Store, F-Droid, or APK, with Tor and VPN support. Both free and paid plans; utilizes quantum-resistant encryption ensuring privacy-focused, anonymous usage.
Web- and IMAP-based email service. 4GB cost 1€/month. Information is hosted on encrypted hard drives. Electricity from renewable resources is used.
Privacy-focused Swiss email system provides 20 GB free storage, supports custom domains and unlimited storage, syncs contacts and calendars, is ad-free, and is part of a secure productivity suite used by over a million users across Europe on all devices.
Finally, an email service that's built around your privacy. Get your @criptext.com email address and see what it's like to have peace of mind and privacy in every email you send.
Swisscows.email is another product of Swisscows AG. This product offers you secure email traffic. With Swisscows.email you can send your emails encrypted so that absolutely no one can read them. The service is comparable to a letter that is protected from prying eyes in an...
Fripost – the Free Email Association. Fripost organize the people who want an alternative to "free" e-mail services where you are constantly under surveillance and personal data is handed over to third parties.
Aster is a privacy-focused, quantum-safe, end-to-end encrypted email service. Unlike other encrypted email providers, Aster uses standard OpenPGP (RSA-4096) with portable keys that work in GPG, Thunderbird, or any other PGP client.
Unofficial, free and open-source Google Inbox Desktop App. Built using electron, Inboxer includes a menu bar which is globalmenu compatible and works, and keyboard shortcuts.
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Functions on secure browsers like Klar and Tor.