Proton Mail AlternativesOnly Open Source apps categorised as Email Clients

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 50 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, Onion Mail and Criptext.

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Proton Mail alternatives are mainly Email Clients, but if you're looking for WebMail Providers or Calendar Apps you can filter on that. Other popular filters include Free, Open Source and Self-Hosted. These are just examples - use the filter bar below to find more specific alternatives to Proton Mail.
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Alternatives list

  1. Tuta Mail icon

    Tuta Mail

     516 likes
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    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.

    103 Tuta Mail alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • iPad
    • Flathub
    • F-Droid
    Tuta Mail screenshot 1
     
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    10
    153
    Comments about Tuta Mail as an Alternative to Proton Mail
    Comment summary: Tutanota is praised for its affordability and transparency, offering end-to-end encryption and a generous free storage plan that appeals to budget-conscious users. However, users note a wait period for account activation. It is considered user-friendly, though Proton Mail is seen as more secure but pricier. Tutanota encrypts titles and contacts, which some believe gives it an edge in privacy. Overall, it functions well on secure browsers and maintains a straightforward encryption model.
    Top Positive Comment
    Advik
    3

    Tutanota is end-to-end encrypted, as well offers 1 GB mail storage on free plan. The pro plans are cheap compared to protonmail, so it's better for low budget users

    Conner Vieira
    Positive
    -2

    Tutanota has historically been a lot more transparent, and arguably has been more honest about issues and plans

    Ada Byron
    Positive
    1

    I use both, ProtonMail is more secure but also more expensive and not as user-friendly. You cannot beat the price of Tutanota for service they provide.

    Show more comments
    3 of 10 comments
    Proton Mail Icon
    Tuta Mail icon

    • Almost everyone thinks Tuta Mail is a great Proton Mail alternative.

    • Tuta Mail is the most popular Web-based, Windows, Android & Mac alternative to Proton Mail.

    • Tuta Mail is the most popular Open Source & free alternative to Proton Mail.

    • Tuta Mail is Freemium and Open SourceProton Mail is also Freemium and Open Source
    • Tuta Mail is LightweightProton Mail is not according to our users
  2. Posteo icon

    Posteo

     83 likes
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    Web- and IMAP-based email service. 2GB cost 1€/month. Information is hosted on encrypted hard drives. Electricity from renewable resources is used.

    74 Posteo alternatives

    Cost / License

    • Subscription
    • Open Source

    Application types

    Platforms

    • Online
    Drag and drop
     
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    26
    Comments about Posteo as an Alternative to Proton Mail
    John Fastman
    Positive
    2

    Posteo could be a good Protonmail alternative. It offers email encryption in a similar way: Posteo's people, government surveillance and successful hackers won't get into your email content. It also offers a calendar feature, which protonmail users have been crying out for for years.

    Proton Mail Icon
    Posteo icon

    • Almost everyone thinks Posteo is a great Proton Mail alternative.

    • Posteo is the most popular commercial alternative to Proton Mail.

    • Posteo is Paid and Open SourceProton Mail is Freemium and Open Source
    • Posteo is Security-focusedProton Mail is not according to our users
  4. Infomaniak kMail icon

    Infomaniak kMail

     38 likes
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    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.

    42 Infomaniak kMail alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application types

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • F-Droid
    Infomaniak kMail screenshot 1
     
  5. Ad
    Screenshot
    Infomaniak kMail icon
    Infomaniak kMail

    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 acro...

    https://www.infomaniak.com
    Learn More
  6. Onion Mail icon

    Onion Mail

     4 likes
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    The power of simplicity. Onion Mail can manage emails in the normal network and in the Tor. Onion Mail protect your privacy and anonymity.

    31 Onion Mail alternatives

    Cost / License

    • Freemium
    • Open Source

    Application types

    Platforms

    • Online
    • Android
     
  7. Criptext icon

    Criptext

     11 likes
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    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.

    Cost / License

    • Free Personal
    • Open Source

    Application type

    Alerts

    • Discontinued

    Platforms

    • Mac
    • Windows
    • Linux
    • Android
    • iPhone
    Criptext screenshot 1
    Criptext screenshot 2
    Criptext screenshot 3
     
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    1
    7
    Comments about Criptext as an Alternative to Proton Mail
    Guest
    Positive
    3

    Even thought Proton Mail is a good privacy focused email, it still holds both your emails and your keys on their servers. Regarding ownership, Criptext gives the user ownership over their keys, which reside only on the user's devices. It also uses Signal Protocol for encryption which I personally like better than just using pgp.

    Review by a new / low-activity user.
    Proton Mail Icon
    Criptext icon

    • Almost everyone thinks Criptext is a great Proton Mail alternative.

    • Criptext is Free Personal and Open SourceProton Mail is Freemium and Open Source
  8. Swisscows.email icon

    Swisscows.email

     5 likes
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    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...

    Cost / License

    • Subscription
    • Open Source

    Application types

    Platforms

    • Online
    • iPhone
    • iPad
    • Android
    • Android Tablet
    Swisscows.email screenshot 1
     
  10. Fripost icon

    Fripost

     5 likes
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    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.

    Cost / License

    • Paid
    • Open Source

    Application types

    Platforms

    • Online
     
  11. Inboxer icon

    Inboxer

     3 likes
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    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.

    Cost / License

    • Free
    • Open Source

    Application type

    Alerts

    • Discontinued

    Platforms

    • Mac
    • Windows
    • Linux
    Inboxer screenshot 1
     
8 of 8 Proton Mail alternatives