head to head · open source
Cap vs ALTCHA
Cap has 8,236 GitHub stars, 637 forks, 10 open issues and last shipped 5 days ago. ALTCHA has 2,870 stars, 143 forks, 0 open issues and last shipped 12 days ago. Cap leads on adoption by 187% (8,236 vs 2,870 stars). Cap is written in JavaScript under a custom or non-standard licence; ALTCHA is written in TypeScript under MIT. Cap has attracted 8% as many forks as stars, ALTCHA 5%. Cap was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 5 topic tags (anti-abuse, anti-bot, antispam, captcha), 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 | ALTCHA | |
|---|---|---|
| GitHub stars | ★ 8.2K | ★ 2.9K |
| License | Custom / other | MIT |
| Written in | JavaScript | TypeScript |
| Last push | 2026-10-29 | 2026-10-22 |
| Forks | ⑂ 637 | ⑂ 143 |
| 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 ALTCHA if
- You want the ALTCHA feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and ALTCHA 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 ALTCHA
ALTCHA ALTCHA is a self hosted, privacy first security solution that protects your websites, APIs, and online services from spam and abuse through an innovative proof of work mechanism. Unlike traditional CAPTCHAs that depend on intrusive methods like cookies or fingerprinting, ALTCHA delivers robust protection while respecting user privacy. ALTCHA is fully compliant with: Global privacy regulations : GDPR, HIPAA, CCPA, PIPEDA/CPPA, LGPD, DPDPA, and PIPL Accessibility standards : WCAG 2.2 AA level and the European Accessibility Act For more details, visit altcha.org. Playground Want to see it in action? Visit…
read the full ALTCHA overview →
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Frequently asked questions
Is Cap or ALTCHA more popular?
Cap has 8,236 GitHub stars and ALTCHA has 2,870. Cap has the larger community by that measure.
Are Cap and ALTCHA free?
Both are open source. Cap has no licence declared in this registry, and ALTCHA is licensed under MIT. Both are free to self-host.
What is the difference between Cap and ALTCHA?
Cap is written in JavaScript and ALTCHA in TypeScript. 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 ALTCHA?
Choose Cap if you want the larger community (8,236 stars) or its Custom / other licence terms. Choose ALTCHA if its feature set, stack or MIT licence fits better. Both are self-hostable.