Email Apps
Open-source email apps
8 of the 52 email apps in this directory are open source, according to their own sites.
6 of them are free or have a free plan.
Listings checked up to Oct 9, 2026 · Where the facts come from
| Tool | Price | Free plan | Runs on |
|---|---|---|---|
| Proton MailEnd-to-end encrypted email service based in Switzerland | Free plan · from $3.99/mo | Yes | Web, macOS, Windows, Linux, iOS, Android |
| ThunderbirdFree, open-source email app for Windows, macOS, Linux and Android | Free | Free | macOS, Windows, Linux, Android |
| Tuta MailEnd-to-end encrypted email and calendar from Germany | Free plan · from €3/mo | Yes | Web, macOS, Windows, Linux, iOS, Android |
| MailspringOpen-source desktop email client for Mac, Windows and Linux | Free plan · from $8/mo | Yes | macOS, Windows, Linux |
| PosteoAd-free, green-powered email from Berlin for €1 a month | From €1/mo | No | Web |
| FairEmailOpen source, privacy-oriented email client for Android | Free plan · from $7.49 one-time | Yes | Android |
| Inbox ZeroOpen source AI email assistant for Gmail and Outlook | Free trial · from $18/mo | Trial only | Web, macOS, Windows, iOS, Android, Browser extension |
| Wino MailFree, open source mail and calendar app for Windows | Free plan | Yes | Windows |
Common questions
Which email apps are open source?
8 of the 52 email apps in this directory are open source, according to their own sites. They are Proton Mail, Thunderbird, Tuta Mail, Mailspring, Posteo, FairEmail, Inbox Zero and Wino Mail.
Which of these email apps are free?
Proton Mail, Thunderbird, Tuta Mail, Mailspring, FairEmail and Wino Mail 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 each listing names the pages it was read from.