head to head · open source
Cap vs mCaptcha
Cap has 8,236 GitHub stars, 637 forks, 10 open issues and last shipped 5 days ago. mCaptcha has 2,498 stars, 95 forks, 54 open issues and last shipped 1.1 years ago. Cap leads on adoption by 230% (8,236 vs 2,498 stars). Cap is written in JavaScript under a custom or non-standard licence; mCaptcha is written in Rust under AGPL-3.0. Cap has attracted 8% as many forks as stars, mCaptcha 4%. Cap was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (captcha, proof-of-work), 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
| Cap | mCaptcha | |
|---|---|---|
| GitHub stars | ★ 8.2K | ★ 2.5K |
| License | Custom / other | AGPL-3.0 |
| Written in | JavaScript | Rust |
| Last push | 2026-10-29 | 2025-10-07 |
| Forks | ⑂ 637 | ⑂ 95 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Cap if
- You weight community size — 8.2K stars and counting
- You want the Custom / other license terms
- Your stack matches JavaScript
- You value the larger contributor base for long-term maintenance
pick mCaptcha if
- You want the mCaptcha feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Rust
- You evaluated both and mCaptcha fits your workflow better
About Cap
Cap Cap is a lightweight, modern open source CAPTCHA alternative using proof of work and instrumentation challenges . It's fast, private, and extremely simple to integrate. Documentation Read the docs , try the demo or deploy on Railway What is Cap? Cap replaces visual captchas with modern, accessible and privacy preserving challenges. No images, no tracking, no dependencies, works everywhere. The default way to use Cap is with the Standalone Docker container. Learn more about how Cap works Why Cap? 250x smaller than hCaptcha 20kb, zero dependencies, loads in milliseconds Privacy first Cap doesn't send any…
About mCaptcha
mCaptcha Proof of work based, privacy respecting CAPTCHA system with a kickass UX. STATUS: ACTIVE DEVELOPMENT Skip to demo mCaptcha is a privacy respecting, free CAPTCHA system with a kickass UX. Your users no longer have to interact with ridiculous image based CAPTCHA system, wasting precious mental bandwidth. Instead, your computer will do the work for you, see for yourself! How does it work? mCaptcha uses SHA256 based proof of work (PoW) to rate limit users. When a user wants to do something on a mCaptcha protected website, 1. they will have to generate proof of work (a bunch of math that will takes time to…
read the full mCaptcha overview →
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Frequently asked questions
Is Cap or mCaptcha more popular?
Cap has 8,236 GitHub stars and mCaptcha has 2,498. Cap has the larger community by that measure.
Are Cap and mCaptcha free?
Both are open source. Cap has no licence declared in this registry, and mCaptcha is licensed under AGPL-3.0. Both are free to self-host.
What is the difference between Cap and mCaptcha?
Cap is written in JavaScript and mCaptcha in Rust. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Cap or mCaptcha?
Choose Cap if you want the larger community (8,236 stars) or its Custom / other licence terms. Choose mCaptcha if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.