Open Source Email & Communication Tools

Open source email & communication tools

projects 13 combined stars ★ 71K refresh nightly

Email & Communication is one of the most active slices of the open source world — the 13 projects below are ranked by GitHub stars, which makes this page roughly a community-voted shortlist rather than a vendor-curated catalogue. Every card shows the license and the last-commit date, so you can filter out the two failure modes of free software in one glance: restrictive licensing that blocks your use case, and abandonment that leaves you maintaining a fork. When two projects look comparable, prefer the one with more recent activity and the more permissive license (MIT/Apache-2.0 over AGPL) unless copyleft specifically serves your goals. Hover into any project for its full README — the documentation quality is usually the honest tell of engineering quality.

All Email & Communication tools

Ntfy ★ 34K

Simple, fast, and secure push notifications for all

rank001 licenseApache-2.0 written inGo typeEmail & Communication

Inbox Zero ★ 12K

AI email assistant that automates, organizes, and declutters

rank002 licenseNOASSERTION written inTypeScript typeEmail & Communication

Plunk ★ 5.5K

The open-source, affordable email platform

rank003 licenseAGPL-3.0 written inTypeScript typeEmail & Communication

useSend ★ 4.7K

Pay per email sent, not for contact storage

rank004 licenseAGPL-3.0 written inTypeScript typeEmail & Communication

Freescout ★ 4.5K

Open-source helpdesk for seamless customer support

rank005 licenseAGPL-3.0 written inPHP typeEmail & Communication

Keila ★ 2.2K

Open-source email marketing for the privacy-conscious

rank006 licenseAGPL-3.0 written inElixir typeEmail & Communication

Sendportal ★ 2.2K

Self-hosted email marketing with unlimited everything

rank007 licenseMIT written inPHP typeEmail & Communication

UnInbox ★ 1.8K

Transform team email into efficient collaborative workflows

rank008 licenseNOASSERTION written inTypeScript typeEmail & Communication

DoubleZero ★ 1.2K

Self-hosted email infrastructure for developers

rank009 licenseAGPL-3.0 written inElixir typeEmail & Communication

Sessy ★ 929

Own your SES email analytics, from send to inbox

rank010 licenseNOASSERTION written inRuby typeEmail & Communication

Hyvor Relay ★ 897

Open-source email API with enterprise deliverability

rank011 licenseAGPL-3.0 written inPHP typeEmail & Communication

Twake Mail ★ 653

Secure open source email with advanced encryption & AI

rank012 licenseAGPL-3.0 written inDart typeEmail & Communication

AgentMail ★ 38

Email inbox API built for AI agents and workflows

rank013 licenseMIT written inTypeScript typeEmail & Communication

Frequently asked questions

How many open source Email & Communication tools are there?

This registry tracks 13 open source Email & Communication projects, with 71,127 combined GitHub stars. The list is ranked by stars and refreshed nightly.

What is the most popular open source Email & Communication project?

Ntfy leads this category with 34,282 GitHub stars, followed by Inbox Zero.

Are these Email & Communication tools free?

Yes — every project listed here is open source. Some also offer paid hosted versions alongside the free self-hosted option; the licence for each project is shown on its card.