mCaptcha - mCaptcha
mCaptcha is proof-of-work based captcha system that is privacy focused and fully automated.
Categories:
mCaptcha is a privacy-respecting, proof-of-work based CAPTCHA system for developers and website owners to defend against bots and spam without tracking or annoying users.
🚀 Overview
mCaptcha is an open-source CAPTCHA alternative that uses SHA256 proof-of-work (PoW) to rate-limit requests, making it computationally expensive for bots and attackers while being seamless for humans. It eliminates the need for image puzzles, behavioral tracking, or third-party services like reCAPTCHA or hCaptcha.
Traditional CAPTCHAs compromise user privacy, accessibility, and UX. mCaptcha solves this by being fully self-hostable, privacy-focused, and transparent.
Answer these questions:
- What problem does this project solve? Traditional CAPTCHAs track users, have poor UX and accessibility, and rely on opaque ML. mCaptcha provides robust, privacy-preserving bot protection using PoW.
- Who is it built for? Developers, website owners, and teams needing spam/DDoS defense without privacy trade-offs.
- Why did you build it? To create a libre software solution that changes how the web defends itself, funded by NLnet, prioritizing privacy, UX, and accessibility over proprietary trackers.
✨ Key Features
- Privacy focused (what it does and why it matters): No cookies, tracking, or profiling—protects users from surveillance capitalism in CAPTCHAs.
- Seamless UX: Users just click a button for automatic PoW; no images or manual solving needed.
- Robust and accurate: IP-independent rate-limiting works behind NATs, replay-resistant with short-lived tokens.
- Defend like castles: PoW makes DDoS and spam attacks costly for bots.
- Libre and self-hostable: AGPL-3.0 core, easy Docker setup.
- Drop-in replacement: APIs compatible with reCAPTCHA/hCaptcha for easy migration. Optional: Upcoming features via active development on GitHub.
🛠 Tech Stack
- Frontend: TypeScript, HTML, SCSS, Webpack, Jest
- Backend: Rust, Actix-web
- Database: PostgreSQL or MariaDB, Redis
- Auth: Custom (admin panel with users)
- Hosting: Self-hosted, Docker/Docker Compose
👥 Who Is This For?
This project is useful for:
- Developers who want to ___ integrate privacy-friendly anti-bot protection
- Teams looking for ___ self-hosted DDoS/spam defense
- Indie makers building ___ transparent web apps without Big Tech dependencies
📸 Screenshots / Demo
- Live demo: https://demo.mcaptcha.org/
- GitHub: https://github.com/mCaptcha/mCaptcha
🔥 Project Status
- 🟢 Actively building
Last updated: 2026-03-24
❓ FAQ
Is this project free?
Yes / Freemium / Paid / Open Source Fully free and open-source (AGPL-3.0), self-hostable with no costs.
Is the source code available?
Yes — link to repository https://github.com/mCaptcha/mCaptcha
Can I contribute?
See HACKING.md for dev setup. Open issues/PRs on GitHub, join Matrix room, or provide feedback.
📬 Contact & Links
- Website: https://mcaptcha.org/
- GitHub: https://github.com/mCaptcha/mCaptcha
- Twitter/X: https://twitter.com/m_captcha
- Email: realaravinth@batsense.net
Built with ❤️ and kept warm on WarmIndex.
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