Open alternatives5
Open-source apps that replace Gmail and Microsoft Outlook

Tuta Mail is an email service with built-in end-to-end encryption, with open-source apps for web, desktop and phones. It is for people who want private email and are fine using Tuta's own hosted service, which cannot be self-hosted.

Thunderbird is a free, open-source email app for Windows, macOS and Linux that also includes calendars and contacts, with an Android app for email. It suits people who want to manage their email and calendars in one desktop program without relying on a big tech company.

Mailspring is a desktop email app for Windows, Mac and Linux that lets you read and send email from one place. It is aimed at people who want a faster, lighter alternative to web-based or heavy mail clients.

Roundcube is a webmail program you install on your own server so you can read and send email in a web browser. It is meant for people or organizations who want to run their own email web interface.

FairEmail is an email app for Android phones that works with most email providers, including Gmail and Outlook. It is aimed at people who want a privacy-focused way to read and send email.
What's missing
What people still miss here, and wish existed. Upvote what matters to you.
Before you build
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About this page
Replaces fully means it does the main job of these apps; Replaces partly means it covers some of it.
Licenses: every project here uses an open-source license (what each one means). Open core means some parts are paid or under another license.
GitHub stars are shown for reference. They measure popularity, not whether it replaces anything.
Verified means r/TrueOpenSource mods checked it: open-source license, maintained, and it really does the job.
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