StartMail alternatives · Email
Open-source alternatives to StartMail
StartMail is not described as open source on its own site. 16 of the 73 other email apps in this directory are open source, according to their own sites.
StartMail is a paid product with a free trial, starting at $4.99 per month, billed annually ($59.88). 13 of them are free or have a free plan.
16 tools · Listings checked up to Nov 12, 2026 · Where the facts come from
The 12 closest to StartMail
- Free plan · from $3.99/mo
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. StartMail starts at $4.99 per month, billed annually ($59.88).
- Proton Mail has a free plan. StartMail does not, though it has a free trial.
- Only Proton Mail lists macOS, Windows, Linux and iOS apps.
- Proton Mail is open source and end-to-end encrypted, according to its own site.
- Free plan · from €3/mo
Tuta Mail
End-to-end encrypted email and calendar from Germany
- Tuta Mail starts at €3 per month, paid yearly (lowest paid personal plan). StartMail starts at $4.99 per month, billed annually ($59.88).
- Tuta Mail has a free plan. StartMail does not, though it has a free trial.
- Only Tuta Mail lists Windows, macOS, Linux and iOS apps.
- Tuta Mail is open source and end-to-end encrypted, according to its own site.
- From €1/mo
Posteo
Ad-free, green-powered email from Berlin for €1 a month
- Posteo starts at €1 per month, prepaid (minimum top-up €12). StartMail starts at $4.99 per month, billed annually ($59.88).
- Only StartMail lists an Android app.
- Posteo is open source and end-to-end encrypted, according to its own site.
- Posteo also covers notes and calendar.
- Free trial · from $18/mo
Inbox Zero
Open source AI email assistant for Gmail and Outlook
- Inbox Zero starts at $18 per user / month, billed annually ($20 billed monthly). StartMail starts at $4.99 per month, billed annually ($59.88).
- Only Inbox Zero lists macOS, Windows and iOS apps.
- Only Inbox Zero lists a browser extension.
- Inbox Zero is open source and self-hostable, according to its own site.
- Free plan · from $20/mo
Zero Mail
Open-source AI email client that connects your existing inboxes
- Zero Mail starts at $20 per month (billing basis not shown). StartMail starts at $4.99 per month, billed annually ($59.88).
- Zero Mail has a free plan. StartMail does not, though it has a free trial.
- Only StartMail lists an Android app.
- Zero Mail is open source and self-hostable, according to its own site.
- Free
Claws Mail
Lightweight GTK email and news client, free under the GPL
- Claws Mail is free. StartMail starts at $4.99 per month, billed annually ($59.88).
- Claws Mail has a free plan. StartMail does not, though it has a free trial.
- Only Claws Mail lists Linux and Windows apps.
- Only StartMail lists a web app.
- Free
Thunderbird
Free, open-source email app for Windows, macOS, Linux and Android
- Thunderbird is free. StartMail starts at $4.99 per month, billed annually ($59.88).
- Thunderbird has a free plan. StartMail does not, though it has a free trial.
- Only Thunderbird lists Windows, macOS and Linux apps.
- Only StartMail lists a web app.
- Free plan · from $8/mo
Mailspring
Open-source desktop email client for Mac, Windows and Linux
- Mailspring starts at $8 per month, or $85 per year (Mailspring Pro). StartMail starts at $4.99 per month, billed annually ($59.88).
- Mailspring has a free plan. StartMail does not, though it has a free trial.
- Only Mailspring lists macOS, Windows and Linux apps.
- Only StartMail lists a web app.
- Free plan · from $7.49 one-time
FairEmail
Open source, privacy-oriented email client for Android
- FairEmail starts at $7.49 one-time (pro features, US Google Play in-app purchase). StartMail starts at $4.99 per month, billed annually ($59.88).
- FairEmail has a free plan. StartMail does not, though it has a free trial.
- Only StartMail lists a web app.
- FairEmail is open source and end-to-end encrypted, according to its own site.
- Free plan
Wino Mail
Free, open source mail and calendar app for Windows
- Wino Mail has a free plan. StartMail does not, though it has a free trial.
- Only Wino Mail lists a Windows app.
- Only StartMail lists a web app.
- Only StartMail lists an Android app.
- Paid
Zimbra
Self-hosted email, calendar and file sharing for organizations
- Only Zimbra lists Windows, macOS, Linux and iOS apps.
- Zimbra is open source and self-hostable, according to its own site.
- Zimbra also covers tasks and calendar.
- StartMail also covers inbox filtering.
- Free
Roundcube
Free open-source webmail client you host yourself
- Roundcube is free. StartMail starts at $4.99 per month, billed annually ($59.88).
- Roundcube has a free plan. StartMail does not, though it has a free trial.
- Only StartMail lists an Android app.
- Roundcube is open source and self-hostable, according to its own site.
Common questions
Is there an open-source alternative to StartMail?
Yes. Proton Mail, Tuta Mail, Posteo, Inbox Zero, Zero Mail, Claws Mail, Thunderbird, Mailspring and 8 more are open source, according to their own sites.
Is StartMail open source?
StartMail is not described as open source on its own site. The listing was checked on Oct 6, 2026 against the pages it cites.
Which of these email apps are free?
Proton Mail, Tuta Mail, Zero Mail, Claws Mail, Thunderbird, Mailspring, FairEmail, Wino Mail and 5 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 12, 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 StartMail: the alternatives its listing names first, then the tools that share the most features with it.