head to head · open source
ECC vs mailcatcher
ECC has 263,932 GitHub stars, 39,482 forks, 210 open issues and last shipped 2 days ago. mailcatcher has 6,779 stars, 605 forks, 43 open issues and last shipped 6 days ago. ECC leads on adoption by 3,793% (263,932 vs 6,779 stars). ECC is written in JavaScript under MIT; mailcatcher is written in Ruby under MIT. ECC has attracted 15% as many forks as stars, mailcatcher 9%. ECC 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
| ECC | mailcatcher | |
|---|---|---|
| GitHub stars | ★ 264K | ★ 6.8K |
| License | MIT | MIT |
| Written in | JavaScript | Ruby |
| Last push | 2026-09-20 | 2026-09-16 |
| Forks | ⑂ 39K | ⑂ 605 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick ECC if
- You weight community size — 264K stars and counting
- You want the MIT license terms
- Your stack matches JavaScript
- You value the larger contributor base for long-term maintenance
pick mailcatcher if
- You want the mailcatcher feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Ruby
- You evaluated both and mailcatcher fits your workflow better
About ECC
ECC is an MIT licensed open source agent harness performance optimization system that gives AI coding agents a coordinated engineering workflow — plan, test, implement, review, verify, remember, improve — for developers working in Claude Code, Codex, OpenCode, Cursor, and other harnesses.
About mailcatcher
MailCatcher is a Ruby SMTP server that catches every message sent to it and serves those messages through a local web interface, and it is made for developers who need to inspect the email their application sends without delivering it to real recipients.
read the full mailcatcher overview →
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Frequently asked questions
Is ECC or mailcatcher more popular?
ECC has 263,932 GitHub stars and mailcatcher has 6,779. ECC has the larger community by that measure.
Are ECC and mailcatcher free?
Both are open source. ECC is licensed under MIT and mailcatcher under MIT. Neither carries a licence fee.
What is the difference between ECC and mailcatcher?
ECC is written in JavaScript and mailcatcher in Ruby. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, ECC or mailcatcher?
Choose ECC if you want the larger community (263,932 stars) or its MIT licence terms. Choose mailcatcher if its feature set, stack or MIT licence fits better. Both are self-hostable.