Open-source alternatives guide · Updated 2026

Best open-source alternatives to Gmail

Compare the best free and open-source alternatives to Gmail — 4 verified projects with explicit catalog relationships. Inspect licenses, GitHub activity, self-hosting signals, and migration fit before you switch.

4verified alternatives
2self-hosted signals
3categories

Only explicit alternative relationships are shown—never inferred competitor claims.

Overview

This guide compares 4 verified open-source alternatives to Gmail, including Zero, Tuta, UnInbox, and Twake Mail.

Projects appear across AI & Machine Learning, Security & Privacy, and Infrastructure. 2 options include a self-hosting signal — see the self-hosted catalog. Ranking follows public GitHub stars and recorded momentum—not vendor marketing. Compare projects side by side, then confirm license fit, migration effort, and operational ownership before adopting any option.

Strongest repository-activity signal: Zero · Jump to ranking · 10.7K stars

About Gmail

Proprietary product with documented open-source alternatives cataloged on OpenSourceChoice. Compare licenses, repository activity, and self-hosting options befo

Ranked open-source alternatives to Gmail

Compare capabilities, licensing, and ownership model. Stars help with discovery; they are not a security or product-fit guarantee.

Zero

Open-source alternative to Gmail

AI & Machine LearningMITAI-native

Experience email the way you want with Mail0 – the first open source email app that puts your privacy and safety first. Join the discord: https://mail0.link/discord

Experience email the way you want with Mail0 – the first open source email app that puts your privacy and safety first. Join the discord: https://mail0.link/discord Review the offi

Best for: AI product teams
Deployment: Inspectable source
License: MIT
Activity: Updated 2 months ago

Key capabilities

privacy

security

Tuta

Open-source alternative to Gmail

Security & PrivacyGPL-3.0

Tuta is an email service with a strong focus on security and privacy that lets you encrypt emails, contacts and calendar entries on all your devices.

Tuta is an email service with a strong focus on security and privacy that lets you encrypt emails, contacts and calendar entries on all your devices. Review the official repository

Best for: Security teams
Deployment: Inspectable source
License: GPL-3.0
Activity: Updated 28 hours ago

Key capabilities

javascript

privacy

security

UnInbox

Open-source alternative to Gmail

InfrastructureLicense not declaredSelf-hosted

Modern email for teams and professionals. A replacement for outdated email technology and tools. Alt to hey.com, front.com, missiveapp.com

Modern email for teams and professionals. A replacement for outdated email technology and tools. Alt to hey.com, front.com, missiveapp.com Review the official repository, license,

Best for: Infrastructure teams
Deployment: Self-hostable
License: License not declared
Activity: Updated 5 months ago

Key capabilities

self-hosted

react

nextjs chat

Twake Mail

Open-source alternative to Gmail

InfrastructureAGPL-3.0Self-hosted

A multi-platform (Flutter) application for reading your emails, with your favorite devices, using the JMAP protocol!

A multi-platform (Flutter) application for reading your emails, with your favorite devices, using the JMAP protocol! Review the official repository, license, release activity, and

Best for: Infrastructure teams
Deployment: Self-hostable
License: AGPL-3.0
Activity: Updated 33 hours ago

Key capabilities

hacktoberfest

flutter

mobile

How to choose a Gmail alternative

Map must-have capabilitiesList the workflows in Gmail you cannot drop during migration.

Verify the licenseConfirm it fits your use, distribution, and compliance model. Browse license briefs.

Run a proof of conceptTest real data, integrations, clients, and failure modes. Use Compare for side-by-side checks.

Plan ownershipAssess upgrades, backups, support, and an exit path. Read when self-hosting is worth it.

Frequently asked questions about Gmail alternatives

What are the best open-source alternatives to Gmail?

OpenSourceChoice currently lists 4 projects with an explicit alternative relationship to Gmail. Catalog highlights include Zero, Tuta, and UnInbox. Rankings follow public GitHub stars and recorded momentum—not paid placement. Match capabilities and license fit to your workflow before adopting any option.

Are open-source alternatives to Gmail free?

Most catalogued alternatives publish source under OSI or source-available licenses and are free to inspect. Hosting, commercial support, or cloud model APIs may still cost money. Always read the project license for your use case.

Can I self-host an alternative to Gmail?

2 options in this list carry a self-hosting signal. Confirm the official install guide, backups, upgrades, and hardening steps before production.

How should I evaluate Gmail alternatives?

Map must-have Gmail workflows, verify license and compliance fit, run a proof of concept with real data and integrations, then plan ownership for upgrades, backups, support, and an exit path.

Browse and filter the catalog

Narrow the same alternatives by search, license, tags, or self-hosting signals when you need a tighter shortlist.

Zero

MIT

Experience email the way you want with Mail0 – the first open source email app that puts your privacy and safety first. Join the discord: https://mail0.link/discord