Open Source Web-based Proton Mail Alternatives

There are many alternatives to Proton Mail as a web app if you are looking for a replacement. The best open source Online alternative is Tuta Mail. If that doesn't suit you, our users have ranked more than 100 alternatives to Proton Mail and 17 are open source and available as a web app so hopefully you can find a suitable replacement. Other interesting open source Online alternatives to Proton Mail are Posteo, Disroot, Infomaniak kMail and Kolab Now.

filter to find the best alternatives

Proton Mail alternatives are mainly WebMail Providers, but if you're looking for Email Clients or Calendar Apps you can filter on that. Other popular filters include Free, Self-Hosted and Open Source. 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
     560 likes

    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.

    108 Tuta Mail alternatives

    Cost / License

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • iPad
    • Flathub
    • F-Droid
    • Android Tablet
    • Thunderbird
     
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    10
  2. Posteo icon
     89 likes

    Web- and IMAP-based email service. 4GB cost 1€/month. Information is hosted on encrypted hard drives. Electricity from renewable resources is used.

    79 Posteo alternatives

    Cost / License

    • Paid
    • Open Source

    Platforms

    • Online
     
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    1
  3. Disroot icon
     120 likes

    Disroot is a platform providing online services based on principles of freedom, privacy, federation and decentralization.

    Cost / License

    • Free
    • Open Source

    Application type

    Platforms

    • Online
    • F-Droid
     
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    3
  4. 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.

    49 Infomaniak kMail alternatives

    Cost / License

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • F-Droid
     
  5. Kolab Now icon
     43 likes

    Kolab Now provides a suite of intuitive apps in a user friendly environment to make your day to day online comms easier, smarter and most importantly; secure.

    Cost / License

    • Paid
    • Open Source

    Platforms

    • Online
    • Software as a Service (SaaS)
    • DAVx5
     
  6. Forward Email icon
     8 likes

    Forward Email is the best email service, encrypted email service, and fastest email service. It supports unlimited domains and aliases for no extra cost. It uses quantum safe ChaCha20-Poly1305 encryption and offers SMTP, IMAP, POP3, email webhooks, email regular expressions...

    40 Forward Email alternatives

    Cost / License

    Application type

    Platforms

    • Self-Hosted
    • Online
     
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    1
  7. 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

    • Paid
    • Open Source

    Platforms

    • Online
    • iPhone
    • iPad
    • Android
    • Android Tablet
     
  8. Zero Email icon
     6 likes

    Zero is an open-source AI email solution that gives users the power to self-host their own email app while also integrating external services like Gmail and other email providers. Our goal is to modernize and improve emails through AI agents to truly modernize emails.

    Cost / License

    • Free
    • Open Source (MIT)

    Application type

    Platforms

    • Online
    • Self-Hosted
    • Docker
     
  9. systemli.org icon
     5 likes

    Systemli.org is a left network and technics-collective that was founded in 2003. Our aim is to provide safe and trustworthy communication services. The project addresses political activists and people who have a particular need to protect their data.

    Cost / License

    • Free
    • Open Source

    Platforms

    • Online
     
  10. Unofficial ProtonMail extension. Provides notifications and makes it possible to close the ProtonMail tab, and even the browser, without getting logged out.

    Cost / License

    • Free
    • Open Source

    Platforms

    • Online
    • ProtonMail
    • Google Chrome
    • Firefox
     
  11. Galae icon
     1 like

    Galae is a secure email service focused on deliverability, self-management and interoperability. It totally relies on free/libre opensource software.

    Cost / License

    Application type

    Platforms

    • Online
    • Software as a Service (SaaS)
     
  12. SwisMail icon
     1 like

    Secure Free EMail Service Hosted in Switzerland.

    Cost / License

    • Freemium
    • Open Source

    Platforms

    • Online
    • Android
    • iPhone
     
12 of 17 Proton Mail alternatives