head to head · open source
ECC vs d2
ECC has 267,023 GitHub stars, 39,902 forks, 232 open issues and last shipped yesterday. d2 has 25,506 stars, 752 forks, 530 open issues and last shipped 5 days ago. ECC leads on adoption by 947% (267,023 vs 25,506 stars). ECC is written in JavaScript under MIT; d2 is written in Go under MPL-2.0. ECC has attracted 15% as many forks as stars, d2 3%. ECC was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (developer-tools), so they are genuine substitutes rather than adjacent tools.
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 | d2 | |
|---|---|---|
| GitHub stars | ★ 267K | ★ 26K |
| License | MIT | MPL-2.0 |
| Written in | JavaScript | Go |
| Last push | 2026-09-24 | 2026-09-20 |
| Forks | ⑂ 40K | ⑂ 752 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick ECC if
- You weight community size — 267K stars and counting
- You want the MIT license terms
- Your stack matches JavaScript
- You value the larger contributor base for long-term maintenance
pick d2 if
- You want the d2 feature set and don't need the biggest community
- You prefer the MPL-2.0 license terms
- Your stack matches Go
- You evaluated both and d2 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 d2
D2 is a modern diagram scripting language, written in Go and released under the MPL 2.0 licence, that turns plain text .d2 files into rendered diagrams such as SVGs, aimed at developers and teams who want their architecture and system diagrams kept as reviewable source rather than as opaque image files.
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Frequently asked questions
Is ECC or d2 more popular?
ECC has 267,023 GitHub stars and d2 has 25,506. ECC has the larger community by that measure.
Are ECC and d2 free?
Both are open source. ECC is licensed under MIT and d2 under MPL-2.0. Neither carries a licence fee.
What is the difference between ECC and d2?
ECC is written in JavaScript and d2 in Go. 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 d2?
Choose ECC if you want the larger community (267,023 stars) or its MIT licence terms. Choose d2 if its feature set, stack or MPL-2.0 licence fits better. Both are self-hostable.