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 50 alternatives to Proton Mail and 12 are Calendar Apps so hopefully you can find a suitable replacement. Other interesting Calendar App alternatives to Proton Mail are Posteo, Mailbox.org, Mailfence and Fastmail.

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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. These are just examples - use the filter bar below to find more specific alternatives to Proton Mail.
Proton Mail iconProton Mail
  939
  • ...

Secure Swiss-based email with end-to-end encryption and zero third-party access. Available across devices, offering a free version to promote privacy.

More about Proton Mail
More about Proton Mail
Proton Mail alternatives page was last updated May 12, 2025
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  1. Tuta Mail icon

    Tuta Mail

     488 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.

    100 Tuta Mail alternatives

    License model

    • Freemium • Open Source

    Application types

    Country of Origin

    • DE flagGermany
    • European Union flagEU

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • iPad
    • Flathub
    • F-Droid
    Mail View

    Properties

    1.  Privacy focused
    2.  Lightweight
    3.  Clean design

    Features

    1.  Encrypted Email
    2.  End-to-End Encryption
    3.  Dark Mode
    4.  Custom Domain
    5.  Encrypted calendar
    6.  Contacts
    7.  No Tracking
    8.  Multiple Account support
    9.  Integrated File Sharing
    10.  Ad-free
    11.  Spam Filter
    12.  Email Organizer

    Tuta Mail VS Proton Mail

     
    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
    Feb 1, 2022
    4

    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

    Most Recent Comment
    Conner Vieira
    Positive Sep 13, 2021
    0

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

    Ada Byron
    Positive Sep 12, 2021
    0

    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 Privacy focused and LightweightProton Mail is not according to our users
  2. Posteo icon

    Posteo

     80 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.

    73 Posteo alternatives

    License model

    Application types

    Country of Origin

    • DE flagGermany
    • European Union flagEU

    Platforms

    • Online
    Drag and drop

    Properties

    1.  Privacy focused
    2.  Security-focused

    Features

    1.  Encrypted mail and contacts
    2.  Encrypted Email
    3.  Calendar Integration
    4.  PGP Encryption
    5.  Two-factor Authentication
    6.  Mail Filtering
    7.  Support for Aliases
    8.  No Tracking
    9.  Ad-free
    10.  Calendar View
    11.  Spam Filter
    12.  End-to-End Encryption

    Posteo VS Proton Mail

     
    Comments about Posteo as an Alternative to Proton Mail
    John Fastman
    Positive Apr 28, 2018
    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 ProprietaryProton Mail is Freemium and Open Source
    • Posteo is Privacy focusedProton Mail is not according to our users
  4. Mailbox.org icon

    Mailbox.org

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

    82 Mailbox.org alternatives

    License model

    Application types

    Country of Origin

    • DE flagGermany
    • European Union flagEU

    Platforms

    • Online
    Dashboard online office. Powered by Open-Xchange

    Properties

    1.  Privacy focused

    Features

    1.  Custom Domain
    2.  Encrypted Email
    3.  Built-in Calendar
    4.  Calendar Integration
    5.  Two-factor Authentication
    6.  No Tracking
    7.  Spam Filter
    8.  PGP Encryption
    9.  Dark Mode
    10.  Calendar View
    11.  Ad-free
    12.  GPG Encryption

    Mailbox.org VS Proton Mail

     
    Comments about Mailbox.org as an Alternative to Proton Mail
    John Fastman
    Positive Dec 24, 2016
    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.

    Proton Mail Icon
    Mailbox.org icon

    • Almost everyone thinks Mailbox.org is a great Proton Mail alternative.

    • Mailbox.org is Paid and ProprietaryProton Mail is Freemium and Open Source
    • Mailbox.org is Privacy focusedProton Mail is not according to our users
  5. Ad
    Screenshot
    Fastmail icon
    Fastmail

    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...

    https://www.fastmail.com
    Learn More
  6. Mailfence icon

    Mailfence

     59 likes
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    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.

    71 Mailfence alternatives

    License model

    • Freemium • Proprietary

    Application types

    Country of Origin

    • BE flagBelgium
    • European Union flagEU

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    Mailfence screenshot 1

    Properties

    1.  Privacy focused

    Features

    1.  Calendar Integration
    2.  POP3 Support
    3.  IMAP Support
    4.  Ad-free
    5.  Encrypted Email
    6.  OpenPGP
    7.  Mail Filtering
    8.  PGP Encryption
    9.  AES-256 Encryption
    10.  No Tracking
    11.  Two-factor Authentication
    12.  End-to-End Encryption

    Mailfence VS Proton Mail

     
    Comments about Mailfence as an Alternative to Proton Mail
    Top Positive Comment
    PhmNguynHngThnh
    Oct 1, 2019
    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
    Aug 29, 2020
    2

    Costs money to use with 3rd party programs.

    Most Recent Comment
    Guest
    Positive Mar 15, 2020
    1

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

    Show more comments
    3 of 7 comments
    Proton Mail Icon
    Mailfence icon

    • Most users think Mailfence is a great Proton Mail alternative.

    • Mailfence is the most popular Android Tablet alternative to Proton Mail.

    • Mailfence is Freemium and ProprietaryProton Mail is Freemium and Open Source
    • Mailfence is Privacy focusedProton Mail is not according to our users
  7. Fastmail icon

    Fastmail

     71 likes
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    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.

    72 Fastmail alternatives

    License model

    Application types

    Country of Origin

    • AU flagAustralia

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    Fastmail screenshot 1

    Properties

    1.  Privacy focused

    Features

    1.  Support for Aliases
    2.  Ad-free
    3.  Full-Text Search
    4.  Two-factor Authentication
    5.  Email Organizer
    6.  Reminders
    7.  No Tracking
    8.  Spam Filter
    9.  Calendar Integration
    10.  Calendar View
    11.  Mail Filtering
    12.  Integrated Spam Protection

    Fastmail VS Proton Mail

     
  8. Vivaldi Mail icon

    Vivaldi Mail

     33 likes
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    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...

    99 Vivaldi Mail alternatives

    License model

    • Free • Proprietary

    Application types

    Country of Origin

    • NO flagNorway

    Platforms

    • Online
    • Vivaldi
    Mail

    Properties

    1.  Support for Themes

    Features

    1.  IMAP Support
    2.  Ad-free
    3.  POP3 Support
    4.  PGP Encryption
    5.  Email Organizer
    6.  Mail Filtering
    7.  GPG Encryption
    8.  Two-factor Authentication
    9.  Spam Filter
    10.  Calendar View
    11.  Unified inbox
    12.  Calendar Integration

    Vivaldi Mail VS Proton Mail

     
    Comments about Vivaldi Mail as an Alternative to Proton Mail
    John Fastman
    Positive Apr 28, 2018
    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).

    Proton Mail Icon
    Vivaldi Mail icon

    • Most users think Vivaldi Mail is a great Proton Mail alternative.

    • Vivaldi Mail is Free and ProprietaryProton Mail is Freemium and Open Source
  10. Infomaniak kMail icon

    Infomaniak kMail

     32 likes
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    Infomaniak’s Mail Service is a secure emailing system hosted in Switzerland and is the best (free) alternative to the web giants. Infomaniak’s emailing service is used by more than a million companies and individuals throughout Europe.

    41 Infomaniak kMail alternatives

    License model

    • Freemium • Open Source

    Application types

    Country of Origin

    • CH flagSwitzerland

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • F-Droid
    Infomaniak kMail screenshot 1

    Properties

    1.  Privacy focused

    Features

    1.  Ad-free
    2.  No Tracking
    3.  Portable
    4.  Calendar Integration
    5.  Multiple Account support
    6.  Cloud Sync
    7.  Support for Aliases
    8.  Real time collaboration
    9.  Secure mail
    10.  Sync Contacts
    11.  Calendar Sync
    12.  CardDAV Support

    Infomaniak kMail VS Proton Mail

     
7 of 12 Proton Mail alternatives