head to head · open source
Billion Mail vs OpenOutreach
Billion Mail has 16,185 GitHub stars, 1,803 forks, 236 open issues and last shipped 5 months ago. OpenOutreach has 3,494 stars, 629 forks, 1 open issues and last shipped 13 days ago. Billion Mail leads on adoption by 363% (16,185 vs 3,494 stars). Billion Mail is written in Go under AGPL-3.0; OpenOutreach is written in Python under GPL-3.0. Billion Mail has attracted 11% as many forks as stars, OpenOutreach 18%. OpenOutreach was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Billion Mail | OpenOutreach | |
|---|---|---|
| GitHub stars | ★ 16K | ★ 3.5K |
| License | AGPL-3.0 | GPL-3.0 |
| Written in | Go | Python |
| Last push | 2026-06-11 | 2026-10-23 |
| Forks | ⑂ 1.8K | ⑂ 629 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Billion Mail if
- You weight community size — 16K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches Go
- You value the larger contributor base for long-term maintenance
pick OpenOutreach if
- You want the OpenOutreach feature set and don't need the biggest community
- You prefer the GPL-3.0 license terms
- Your stack matches Python
- You evaluated both and OpenOutreach fits your workflow better
About Billion Mail
BillionMail 📧 An Open Source MailServer, NewsLetter, Email Marketing Solution for Smarter Campaigns [![][license shield]][license link] [![][docs shield]][docs link] [![][github release shield]][github release link] [![][github stars shield]][github stars link] English 简体中文 日本語 Türkçe What is BillionMail? BillionMail is a future open source Mail server, Email marketing platform designed to help businesses and individuals manage their email campaigns with ease. Whether you're sending newsletters, promotional emails, or transactional messages, this tool will provide full control over your email marketing efforts…
read the full Billion Mail overview →
About OpenOutreach
OpenOutreach — open source AI agent for B2B lead generation Describe your product. Define your target market. The AI finds the people who fit, tells you why each one does, and emails them. Self hosted CLI. One install, one onboarding, one command. Demo 🚀 What is OpenOutreach? OpenOutreach is a self hosted, open source lead finder that qualifies for you — and then writes the email. You describe your product and your target market; it discovers matching people from a licensed data provider , judges each one against the ICP it learned from your description, hands you the ones that fit with the reason each was…
read the full OpenOutreach overview →
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Frequently asked questions
Is Billion Mail or OpenOutreach more popular?
Billion Mail has 16,185 GitHub stars and OpenOutreach has 3,494. Billion Mail has the larger community by that measure.
Are Billion Mail and OpenOutreach free?
Both are open source. Billion Mail is licensed under AGPL-3.0 and OpenOutreach under GPL-3.0. Neither carries a licence fee.
What is the difference between Billion Mail and OpenOutreach?
Billion Mail is written in Go and OpenOutreach in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Billion Mail or OpenOutreach?
Choose Billion Mail if you want the larger community (16,185 stars) or its AGPL-3.0 licence terms. Choose OpenOutreach if its feature set, stack or GPL-3.0 licence fits better. Both are self-hostable.