Proton Mail AlternativesOnly apps categorised as Calendar Apps

The best Calendar alternative to Proton Mail is Tuta Mail, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Proton Mail and 13 are Calendar Apps so hopefully you can find a suitable replacement. Other interesting Calendar App alternatives to Proton Mail are Posteo, mailbox, Mailfence and Infomaniak kMail.

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Proton Mail alternatives are mainly Calendar Apps, but if you're looking for WebMail Providers or Email Clients 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

     577 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.

    110 Tuta Mail alternatives

    Cost / License

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • iPad
    • Flathub
    • F-Droid
    • Android Tablet
    • Thunderbird
    Tuta Mail screenshot 1
     
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    10
    Tuta Mail vs Proton Mail Comments
    Top Positive Comment
    Belsima
    11

    Functions on secure browsers like Klar and Tor.

    Advik
    Positive
    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
    -1

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

    3 of 10 comments
    • 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

     90 likes

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

    82 Posteo alternatives

    Cost / License

    • Paid
    • Open Source

    Application types

    Platforms

    • Online
    Drag and drop
     
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    1
    Posteo vs Proton Mail Comments
    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.

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

    mailbox

     77 likes

    E-mail inbox, online office, cloud storage, and video conferencing. Business or personal plans. From 1 € /month (1.10 USD).

    87 mailbox alternatives

    Cost / License

    Application types

    Platforms

    • Online
    mailbox screenshot 1
     
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    1
    mailbox vs Proton Mail Comments
    John Fastman
    Positive
    2

    Mailbox.org is a partial replacement for Protonmail. It offers a fully functional email solution (email, calendar, contacts), but with the added benefits of PGP encryption support (you can handle the keys or let them do it). It also allows you to send links to people who don't use PGP if you want to send private messages. For the encryption, it's a bit like Protonmail. For everything else, it's like a privacy-respecing Gmail alternative.

    • mailbox is Paid and ProprietaryProton Mail is Freemium and Open Source
    • mailbox is Security-focusedProton Mail is not according to our users
  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. Mailfence icon

    Mailfence

     66 likes

    This secure email platform offers end-to-end encryption, a comprehensive suite with Calendar and Documents. Mailfence is inter-operable with OpenPGP services, features digital signatures, provides keystores, and available as a PWA for mobile independence while ensuring no ads, trackers, or surveillance.

    76 Mailfence alternatives

    Cost / License

    • Freemium
    • Proprietary

    Application types

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    Mailfence screenshot 1
     
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    7
    Mailfence vs Proton Mail Comments
    Top Positive Comment
    PhmNguynHngThnh
    5

    Mailfence offers more functionality than Proton mail with Calendar, Document, Chat, and Group functionality. Moreover, the price is much lower than other competitors.

    Top Negative Comment
    Guest
    2

    Costs money to use with 3rd party programs.

    Guest
    Positive
    1

    because its free and don't need any pay and don't want phone number to sign in

    3 of 7 comments
    • Mailfence is Freemium and ProprietaryProton Mail is Freemium and Open Source
  8. Infomaniak kMail icon

    Infomaniak kMail

     51 likes

    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.

    51 Infomaniak kMail alternatives

    Cost / License

    Application types

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • F-Droid
    Infomaniak kMail screenshot 1
     
  9. Fastmail icon

    Fastmail

     79 likes

    Fastmail offers secure email hosting with comprehensive webmail services, including IMAP, POP, and SMTP protocols. It supports file sharing, shared folders, large mailboxes, instant messaging, and is compatible with popular email programs. Excellent for businesses with compliance features.

    81 Fastmail alternatives

    Cost / License

    • Paid
    • Proprietary

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • Flathub
    • Flatpak
    Fastmail screenshot 1
     
  10. Vivaldi Mail icon

    Vivaldi Mail

     35 likes

    Vivaldi Mail is a free email service with no ads and no strings attached developed by Vivaldi Technologies. It also offers contacts and calendar features, search capabilities, folders management, WEB/POP/IMAP access, 10GB of storage capacity, 20 MB of maximum attachment size...

    107 Vivaldi Mail alternatives

    Cost / License

    • Free
    • Proprietary

    Application types

    Platforms

    • Online
    • Vivaldi
    Mail
     
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    1
    Vivaldi Mail vs Proton Mail Comments
    John Fastman
    Positive
    0

    Vivaldi mail offers PGP-based email encryption, similar to Protonmail. But the web client is much less well developed. However, unlike Protonmail (at the time of writing), they allow you to import your own PGP keys, which is nice (a feature Protonmail users have been demanding for years).

    • Vivaldi Mail is Free and ProprietaryProton Mail is Freemium and Open Source
  12. Kolab Now icon

    Kolab Now

     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

    Application types

    Platforms

    • Online
    • Software as a Service (SaaS)
    • DAVx5
    Kolab Now email
     
  13. Mailture icon

    Mailture

     Like

    Mailture, a secure, business-oriented email service, is made to cater to all your emailing needs. With top-notch collaboration and communication features, Mailture offers much more than your usual inbox.

    Cost / License

    • Paid
    • Proprietary

    Application types

    Alerts

    • Discontinued

    Platforms

    • Software as a Service (SaaS)
    Account Overview
     
  14. mail2world icon

    mail2world

     3 likes

    the free email that has everyone talking!.

    73 mail2world alternatives

    Cost / License

    • Freemium
    • Proprietary

    Application types

    Platforms

    • Online
     
  15. VFEmail icon

    VFEmail

     6 likes

    Free email with privacy and security.

    Cost / License

    • Freemium
    • Proprietary

    Application types

    Platforms

    • Online
     
12 of 13 Proton Mail alternatives