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Stacks / Auth

Easy

ALTCHA / mCaptcha

A CAPTCHA you host. ALTCHA is MIT proof-of-work; mCaptcha is AGPL-3.0 — Google reCAPTCHA without the third-party widget.

The problem

Google reCAPTCHA is a third-party bot widget (and a privacy review). You wanted a challenge on a box you run. ALTCHA is MIT (altcha-org/altcha) — proof-of-work, self-hosted. mCaptcha is AGPL-3.0 (mCaptcha/mCaptcha) if you want that PoW backend. This is not every reCAPTCHA Enterprise score, or Cloudflare Turnstile (not open source). Login still stays on /replace/clerk.

Replaces

Google reCAPTCHA

Replace Google reCAPTCHA

Estimated SaaS saved

$1,200

per year, small team, before lock-in

Start on Railway

SuperTokens / PocketBase if this is login, not a bot widget

Sponsor this stack Tip jar

Placeholder: ALTCHA ships as a widget plus optional server checks; mCaptcha is a self-hosted backend. Bind HTTP to 0.0.0.0:$PORT. No one-click template in this repo yet — Start on Railway. Auth stays on /stacks/auth-without-the-bill.

The stack

Cost table

You stop payingTypical / yearSelf-host instead
Google reCAPTCHA (site)$1,200ALTCHA or mCaptcha

Agent setup prompt

Replace Google reCAPTCHA with ALTCHA (preferred) or mCaptcha.

- Drop the reCAPTCHA script. Put ALTCHA on the form that currently loads Google. Self-host mCaptcha if you want that AGPL backend.
- Confirm one form submit. Do not claim reCAPTCHA Enterprise scores. Write AGENT_PROMPT.md.

Also as markdown: /stacks/altcha-captcha.md

FAQ

ALTCHA or mCaptcha?
ALTCHA if you want the MIT widget. mCaptcha if you want an AGPL PoW backend. Pick one.
Why not Turnstile?
Cloudflare Turnstile is not open source. This site skips it.
Is this login?
No. Login is /replace/clerk. This page is the bot widget on a form.