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GMX Mail alternatives · Email

Open-source alternatives to GMX Mail

GMX Mail is not described as open source on its own site. 39 of the 125 other email apps in this directory are open source, according to their own sites.

GMX Mail is free to use. 33 of them are free or have a free plan.

39 tools · Listings checked up to Nov 13, 2026 · Where the facts come from

The 12 closest to GMX Mail

  1. Proton Mail

    End-to-end encrypted email service based in Switzerland

    • Proton Mail starts at $3.99 per month, billed every 12 months ($47.88); $4.99 billed monthly. GMX Mail is free.
    • Only Proton Mail lists macOS, Windows and Linux apps.
    • Only GMX Mail lists a browser extension.
    • Proton Mail is open source and end-to-end encrypted, according to its own site.
    Proton Mail vs GMX MailProton Mail pricing and details

  2. Thunderbird

    Free, open-source email app for Windows, macOS, Linux and Android

    • Thunderbird is free. GMX Mail is free.
    • Only Thunderbird lists Windows, macOS and Linux apps.
    • Only GMX Mail lists a web app.
    • Only GMX Mail lists an iOS app.
    Thunderbird pricing and details

  3. Tuta Mail

    End-to-end encrypted email and calendar from Germany

    • Tuta Mail starts at €3 per month, paid yearly (lowest paid personal plan). GMX Mail is free.
    • Only Tuta Mail lists Windows, macOS and Linux apps.
    • Only GMX Mail lists a browser extension.
    • Tuta Mail is open source and end-to-end encrypted, according to its own site.
    Tuta Mail pricing and details

  4. Posteo

    Ad-free, green-powered email from Berlin for €1 a month

    • Posteo starts at €1 per month, prepaid (minimum top-up €12). GMX Mail is free.
    • GMX Mail has a free plan. Posteo does not.
    • Only GMX Mail lists iOS and Android apps.
    • Only GMX Mail lists a browser extension.
    Posteo pricing and details

  5. Inbox Zero

    Open source AI email assistant for Gmail and Outlook

    • Inbox Zero starts at $18 per user / month, billed annually ($20 billed monthly). GMX Mail is free.
    • GMX Mail has a free plan. Inbox Zero does not, though it has a free trial.
    • Only Inbox Zero lists macOS and Windows apps.
    • Inbox Zero is open source and self-hostable, according to its own site.
    Inbox Zero pricing and details

  6. Wino Mail

    Free, open source mail and calendar app for Windows

    • Only Wino Mail lists a Windows app.
    • Only GMX Mail lists a web app.
    • Only GMX Mail lists iOS and Android apps.
    • Only GMX Mail lists a browser extension.
    Wino Mail pricing and details

  7. Zero Mail

    Open-source AI email client that connects your existing inboxes

    • Zero Mail starts at $20 per month (billing basis not shown). GMX Mail is free.
    • Only GMX Mail lists iOS and Android apps.
    • Only GMX Mail lists a browser extension.
    • Zero Mail is open source and self-hostable, according to its own site.
    Zero Mail pricing and details

  8. Zimbra

    Self-hosted email, calendar and file sharing for organizations

    • GMX Mail has a free plan. Zimbra does not.
    • Only Zimbra lists Windows, macOS and Linux apps.
    • Only GMX Mail lists a browser extension.
    • Zimbra is open source and self-hostable, according to its own site.
    Zimbra pricing and details

  9. Evolution

    GNOME's free mail, calendar and address book app

    • Evolution is free. GMX Mail is free.
    • Only Evolution lists a Linux app.
    • Only GMX Mail lists a web app.
    • Only GMX Mail lists iOS and Android apps.
    Evolution pricing and details

  10. Claws Mail

    Lightweight GTK email and news client, free under the GPL

    • Claws Mail is free. GMX Mail is free.
    • Only Claws Mail lists Linux and Windows apps.
    • Only GMX Mail lists a web app.
    • Only GMX Mail lists iOS and Android apps.
    Claws Mail pricing and details

  11. Betterbird

    A fork of Thunderbird with extra features and bug fixes

    • Betterbird is free. GMX Mail is free.
    • Only Betterbird lists Windows, macOS and Linux apps.
    • Only GMX Mail lists a web app.
    • Only GMX Mail lists iOS and Android apps.
    Betterbird pricing and details

  12. Sylpheed

    Lightweight desktop email client built on GTK+

    • Sylpheed is free. GMX Mail is free.
    • Only Sylpheed lists Windows, macOS and Linux apps.
    • Only GMX Mail lists a web app.
    • Only GMX Mail lists iOS and Android apps.
    Sylpheed pricing and details

27 more that are open source

All 39 in one table

Common questions

Is there an open-source alternative to GMX Mail?

Yes. Proton Mail, Thunderbird, Tuta Mail, Posteo, Inbox Zero, Wino Mail, Zero Mail, Zimbra and 31 more are open source, according to their own sites.

Is GMX Mail open source?

GMX Mail is not described as open source on its own site. The listing was checked on Nov 12, 2026 against the pages it cites.

Which of these email apps are free?

Proton Mail, Thunderbird, Tuta Mail, Wino Mail, Zero Mail, Evolution, Claws Mail, Betterbird and 25 more are free or have a free plan.

When was this checked?

Each listing shows its own date. On this page they run from Oct 4, 2026 to Nov 13, 2026. Vendors change prices and plans without notice, so confirm on their site before you buy.

This page is built from the listings. A tool is here because its listing says so, and the order is how close each is to GMX Mail: the alternatives its listing names first, then the tools that share the most features with it.