# altcha-org/altcha

GDPR, WCAG 2.2 AA, and EAA compliant, self-hosted CAPTCHA alternative with PoW mechanism.

Repository: https://github.com/altcha-org/altcha
Canonical: https://ross.abutalabs.com/products/altcha
Homepage: https://altcha.org
Language: TypeScript
License: MIT
License Family: permissive
Topics: antispam, captcha, hcaptcha, recaptcha, svelte, captcha-alternative, spam-detection, spam-prevention, spam-api, ddos-protection, proof-of-work, ddos-mitigation, spam-protection, wcag, anti-abuse, anti-bot, privacy, security
Last push: 2026-08-19T04:24:45+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 98, release rhythm 98, longevity 72
- inputs: {"age_days": 1019, "days_push": 14, "days_rel": 14, "gap_med": 8, "n_releases_24m": 42}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2708, forks 133 (observed 2026-08-28T04:07:11.710976+00:00)

## What it is
ALTCHA is an open-source, privacy-first CAPTCHA alternative that protects websites, forms, and APIs from bots and spam using a proof-of-work mechanism instead of cookies, tracking, or fingerprinting. It ships as a lightweight JavaScript widget with server-side verification libraries, and is GDPR, HIPAA, and WCAG 2.2 AA compliant while being fully self-hostable.

## Use cases
- stop spam submissions on contact forms
- replace reCAPTCHA with a GDPR-compliant alternative
- block fake sign-ups and bot registrations
- add accessible bot protection for visually impaired users
- self-host CAPTCHA without third-party tracking
- protect login forms from automated abuse
- add proof-of-work verification to APIs

## When to choose
- you need privacy-compliant (GDPR/HIPAA/CCPA) bot protection with no cookies or fingerprinting
- accessibility compliance (WCAG 2.2 AA, EAA) is required
- you want self-hosted protection with full data sovereignty
- you want a frictionless, invisible challenge for most users
- you need a lightweight widget with framework starters for React, Vue, Svelte, Angular, and more

## When to avoid
- you need advanced adaptive bot detection with machine learning and threat intelligence without building it yourself (consider the commercial Sentinel/Cloud offerings)
- your threat model requires image-based CAPTCHA puzzles or human interaction challenges
- you cannot run a server-side challenge generation and verification endpoint and prefer a fully managed free service

## Facets
- artifact type: library
- maturity: active
- function: security, middleware, ui-components, http-server
- domain: security, web-development, privacy, self-hosted
- platform: browser, self-hosted
- tags: captcha-alternative, proof-of-work, anti-bot, anti-spam, gdpr-compliant, wcag-accessible, widget, svelte, ddos-protection, web-server, nodejs, docker

## Member repositories
- altcha-org/altcha (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:11.710976+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 2026-08-30T02:15:41.026582+00:00, confidence not recorded.
  - readme: https://github.com/altcha-org/altcha (fetched 2026-08-28T04:07:11.710976+00:00, sha 962dbac0a48b)
  - homepage: https://altcha.org (fetched 2026-08-29T09:59:18.413308+00:00, sha bd52244014a2)
  - site_page: https://altcha.org/docs (fetched 2026-08-29T09:59:18.424621+00:00, sha 5bcc855dca2f)
  - site_page: https://altcha.org/sentinel-api-docs-v1.html (fetched 2026-08-29T09:59:18.426276+00:00, sha e7eddc80d4b0)
  - site_page: https://altcha.org/docs/integration/quick-start (fetched 2026-08-29T09:59:18.427814+00:00, sha 766b00b4db06)
  - site_page: https://altcha.org/docs/trust (fetched 2026-08-29T09:59:18.429287+00:00, sha 309c07f8ebc0)
  - site_page: https://altcha.org/docs/cloud (fetched 2026-08-29T09:59:18.430943+00:00, sha b03961b72e3d)
  - site_page: https://altcha.org/docs/sentinel (fetched 2026-08-29T09:59:18.432476+00:00, sha b327764ce107)
  - site_page: https://altcha.org/docs/sentinel/install (fetched 2026-08-29T09:59:18.434083+00:00, sha 308cf6aa0c3a)
  - registry_npm: https://registry.npmjs.org/altcha (fetched 2026-08-29T09:59:18.435958+00:00, sha ce80dd569157)
- Data as of 2026-08-30T08:39:29.467469+00:00.