# tiagozip/cap

Free, open-source and self-hosted CAPTCHA alternative to reCAPTCHA. Privacy-first and powered by proof-of-work and instrumentation challenges.

Repository: https://github.com/tiagozip/cap
Canonical: https://ross.abutalabs.com/products/tiagozip-cap
Homepage: https://trycap.dev
Language: JavaScript
License: NOASSERTION
License Family: other
Topics: captcha, javascript, proof-of-work, antispam, anti-abuse, anti-bot, defense, anti-scraper
Last push: 2026-08-14T19:39:12+00:00

## Health v2 (maintenance only)
Score: 81/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 97, release rhythm 82, longevity 42
- inputs: {"age_days": 599, "days_push": 19, "days_rel": 42, "gap_med": 0.0, "n_releases_24m": 121}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 7610, forks 551 (observed 2026-08-28T04:10:01.946899+00:00)

## What it is
Cap is a lightweight, open-source, self-hosted CAPTCHA alternative to reCAPTCHA, hCaptcha, and Cloudflare Turnstile. It uses invisible proof-of-work (SHA-256 via WASM or time-lock challenges) plus instrumentation challenges to verify real browsers, with no tracking or visual puzzles.

## Use cases
- replace reCAPTCHA with a self-hosted captcha
- stop bot signups and spam form submissions
- add anti-bot protection without visual puzzles
- self-host a privacy-first captcha for GDPR compliance
- protect login and comment forms from scrapers
- migrate from reCAPTCHA without rewriting verification code
- run an invisible captcha widget in the background

## When to choose
- you need a self-hosted, privacy-compliant captcha with no third-party telemetry
- you want a tiny (~20kb) widget with zero dependencies
- you want reCAPTCHA siteverify API compatibility for easy migration
- you need accessibility-friendly protection without image puzzles

## When to avoid
- you need advanced human-verification like behavioral analysis against sophisticated bot farms
- you cannot run your own server or Docker container
- you require a fully managed SaaS captcha service

## Facets
- artifact type: library
- maturity: active
- function: security, middleware, wasm, self-hosted
- domain: security, web-development, privacy, self-hosted
- platform: self-hosted, browser, cross-platform
- tags: captcha, proof-of-work, anti-bot, antispam, anti-scraper, recaptcha-alternative, privacy-first, invisible-captcha, web-server, docker, nodejs

## Member repositories
- tiagozip/cap (main) score 81

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:01.946899+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:36:50.553407+00:00, confidence not recorded.
  - readme: https://github.com/tiagozip/cap (fetched 2026-08-28T04:10:01.946899+00:00, sha f6c36c6300f0)
  - homepage: https://trycap.dev (fetched 2026-08-29T08:32:27.449841+00:00, sha 8ab86ab9fca7)
  - site_page: https://trycap.dev/guide (fetched 2026-08-29T08:32:27.452724+00:00, sha c4a0fd25ca40)
- Data as of 2026-08-30T08:39:29.467469+00:00.