● Service online

Prove your users are human.
On any website.

captcha.eval8.ai is the human-verification service of the eval8 platform. Redirect users here before any sensitive action — they pass three challenges backed by behavioral bot detection, and return to your site with a one-time token your backend can trust.

🖱️

Mouse-only checkbox

Keyboard and scripted activation are physically impossible. Cursor trajectory is analyzed for human motion.

🔤

Text CAPTCHA

Distorted characters generated and validated entirely server-side, with keystroke-dynamics analysis while you type.

Press & hold

Hold a button until the bar fills — the duration is randomized per session and enforced on the server clock. Release timing exposes scripts.

How it works

1

Redirect

Your site sends the user to /challenge with your public site key and a whitelisted return URL.

2

Verify human

The user completes the three challenges while behavioral signals are scored server-side.

3

Return with token

The user comes back to your site carrying a single-use eval8-token valid for 5 minutes.

4

Confirm server-side

Your backend posts its secret key + token to /api/siteverify and gets a definitive yes/no.

Quick start

# 1. Send the user to the challenge page
GET /challenge?site_key=eval8-xxx&redirect_uri=https://yoursite.com/resume&state=abc

# 2. They come back to you as
https://yoursite.com/resume?captcha_token=eval8-token-xxx&state=abc

# 3. Confirm from your backend (never from the browser)
POST /api/siteverify   { "secret": "eval8-secret-xxx", "token": "eval8-token-xxx" }
# → { "success": true, "challenge_ts": "…", "hostname": "yoursite.com" }