head to head · open source
Cap vs Private Captcha
Cap has 7,798 GitHub stars, 579 forks, 10 open issues and last shipped 2 days ago. Private Captcha has 195 stars, 6 forks, 4 open issues and last shipped yesterday. Cap leads on adoption by 3,899% (7,798 vs 195 stars). Cap is written in JavaScript under a custom or non-standard licence; Private Captcha is written in Go under a custom or non-standard licence. Cap has attracted 7% as many forks as stars, Private Captcha 3%. Private Captcha was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 4 topic tags (anti-abuse, anti-bot, 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 | Private Captcha | |
|---|---|---|
| GitHub stars | ★ 7.8K | ★ 195 |
| License | Custom / other | Custom / other |
| Written in | JavaScript | Go |
| Last push | 2026-09-16 | 2026-09-17 |
| Forks | ⑂ 579 | ⑂ 6 |
| 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 Private Captcha if
- You want the Private Captcha feature set and don't need the biggest community
- You prefer the Custom / other license terms
- Your stack matches Go
- You evaluated both and Private Captcha 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 Private Captcha
Private Captcha is an independent, privacy first, self hostable Proof of Work CAPTCHA service built in the European Union. The project provides bot protection for web applications by asking visitors to solve a computational challenge rather than identifying distorted images or clicking through behavioral tests. The backend is written in Go and serves both the API and the portal, while the client side ships as a JavaScript widget that uses WebAssembly workers where possible. Business data such as accounts and properties is stored in Postgres, and operational data such as difficulty scaling and statistics is stored…
read the full Private Captcha overview →
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Frequently asked questions
Is Cap or Private Captcha more popular?
Cap has 7,798 GitHub stars and Private Captcha has 195. Cap has the larger community by that measure.
Are Cap and Private Captcha free?
Neither Cap nor Private Captcha declares a licence in this registry, so check each project's own repository before relying on either for a commercial use. Both are free to self-host.
What is the difference between Cap and Private Captcha?
Cap is written in JavaScript and Private Captcha 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, Cap or Private Captcha?
Choose Cap if you want the larger community (7,798 stars) or its Custom / other licence terms. Choose Private Captcha if its feature set, stack or Custom / other licence fits better. Both are self-hostable.