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Spark Mail alternatives · Email

Open-source alternatives to Spark Mail

Spark Mail is not described as open source on its own site. 8 of the 51 other email apps in this directory are open source, according to their own sites.

Spark Mail has a free plan. Paid plans start at $8.25 per user / month, billed annually ($99 / year). 6 of them are free or have a free plan.

8 tools · Listings checked up to Oct 9, 2026 · Where the facts come from

How each one differs from Spark Mail

  1. Wino Mail

    Free, open source mail and calendar app for Windows

    • Only Spark Mail lists macOS, iOS and Android apps.
    • Wino Mail is open source, according to its own site.
    • Wino Mail also covers tasks.
    • Spark Mail also covers meeting notes and shared inbox.
    Wino Mail pricing and details

  2. 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. Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Only Proton Mail lists a web app.
    • Only Proton Mail lists a Linux app.
    • Proton Mail is open source and end-to-end encrypted, according to its own site.
    Proton Mail pricing and details

  3. Thunderbird

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

    • Thunderbird is free. Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Only Thunderbird lists a Linux app.
    • Only Spark Mail lists an iOS app.
    • Thunderbird is open source, according to its own site.
    Thunderbird pricing and details

  4. Tuta Mail

    End-to-end encrypted email and calendar from Germany

    • Tuta Mail starts at €3 per month, paid yearly (lowest paid personal plan). Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Only Tuta Mail lists a web app.
    • Only Tuta Mail lists a Linux app.
    • Tuta Mail is open source and end-to-end encrypted, according to its own site.
    Tuta Mail pricing and details

  5. Mailspring

    Open-source desktop email client for Mac, Windows and Linux

    • Mailspring starts at $8 per month, or $85 per year (Mailspring Pro). Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Only Mailspring lists a Linux app.
    • Only Spark Mail lists iOS and Android apps.
    • Mailspring is open source, according to its own site.
    Mailspring pricing and details

  6. Posteo

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

    • Posteo starts at €1 per month, prepaid (minimum top-up €12). Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Spark Mail has a free plan. Posteo does not.
    • Only Posteo lists a web app.
    • Only Spark Mail lists macOS, Windows, iOS and Android apps.
    Posteo pricing and details

  7. Inbox Zero

    Open source AI email assistant for Gmail and Outlook

    • Inbox Zero starts at $18 per user / month, billed annually ($20 billed monthly). Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Spark Mail has a free plan. Inbox Zero does not, though it has a free trial.
    • Only Inbox Zero lists a web app.
    • Only Inbox Zero lists a browser extension.
    Inbox Zero pricing and details

  8. FairEmail

    Open source, privacy-oriented email client for Android

    • FairEmail starts at $7.49 one-time (pro features, US Google Play in-app purchase). Spark Mail starts at $8.25 per user / month, billed annually ($99 / year).
    • Only Spark Mail lists macOS, Windows and iOS apps.
    • FairEmail is open source and end-to-end encrypted, according to its own site.
    • FairEmail can be bought with a one-time purchase.
    FairEmail pricing and details

Common questions

Is there an open-source alternative to Spark Mail?

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

Is Spark Mail open source?

Spark Mail is not described as open source on its own site. The listing was checked on Oct 4, 2026 against the pages it cites.

Which of these email apps are free?

Wino Mail, Proton Mail, Thunderbird, Tuta Mail, Mailspring and FairEmail 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 Oct 9, 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 Spark Mail: the alternatives its listing names first, then the tools that share the most features with it.