head to head · open source
Cap vs mCaptcha
Cap has 7,798 GitHub stars, 579 forks, 10 open issues and last shipped 2 days ago. mCaptcha has 2,490 stars, 93 forks, 54 open issues and last shipped 12 months ago. Cap leads on adoption by 213% (7,798 vs 2,490 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 7% 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 | ★ 7.8K | ★ 2.5K |
| License | Custom / other | AGPL-3.0 |
| Written in | JavaScript | Rust |
| Last push | 2026-09-16 | 2025-10-07 |
| Forks | ⑂ 579 | ⑂ 93 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Cap if
- You weight community size — 7.8K 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 is a free, open source, self hosted CAPTCHA replacement that swaps visual puzzles for proof of work and instrumentation challenges, built for developers and site operators who want anti bot protection without shipping their visitors' data to a third party service.
About mCaptcha
mCaptcha is a privacy first proof of work CAPTCHA system written in Rust and licensed under AGPL 3.0. It operates as a backend component within the self hosted application security ecosystem, where it provides CAPTCHA, spam protection, and DDoS mitigation for websites and services. The project replaces traditional image based user interaction with an automated computational challenge, so the client device performs the work instead of the human user.
read the full mCaptcha overview →
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Frequently asked questions
Is Cap or mCaptcha more popular?
Cap has 7,798 GitHub stars and mCaptcha has 2,490. 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 (7,798 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.