mCaptcha/mCaptcha

Health v2 · maintenance only

Adoption not part of the score

2486 stars · 94 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

mCaptcha is a self-hosted, privacy-respecting CAPTCHA system that uses SHA-256 proof-of-work to rate-limit users instead of image puzzles. This repository is the backend service that validates proofs of work and issues tokens for websites to verify.

Use cases

• protect a website form from spam bots without annoying image CAPTCHAs
• mitigate DDoS attacks by making requests computationally expensive for clients
• replace Google reCAPTCHA with a self-hosted, tracking-free alternative
• add bot protection to a login or signup flow with seamless UX
• rate limit abusive traffic using variable proof-of-work difficulty

When to choose

• you need a privacy-focused CAPTCHA with no user tracking
• you want to self-host your bot protection instead of relying on third parties
• you prioritize seamless UX over interactive puzzles
• you need DDoS mitigation that scales difficulty with attack load

When to avoid

• you need accessibility features for users on low-powered devices where PoW computation is slow
• you prefer a managed SaaS CAPTCHA with zero infrastructure
• you need a CAPTCHA that blocks fully automated headless browsers with high compute resources

Facets

service · maturity active

security rate-limiting http-server web-framework self-hosted security web-development privacy self-hosted self-hosted rust captcha proof-of-work anti-spam ddos-protection bot-protection privacy-respecting actix-web linux docker web-server

Member repositories

For agents

markdown · JSON · MCP: product_card(name="mCaptcha/mCaptcha")