Play: try real CAPTCHAs and see the server's verdict
Solve real reCAPTCHA, Turnstile, ALTCHA and Cap widgets on our own domain and see what each vendor's server decides. Practice puzzles are coming.
Facts on this page checked 2026-11-03
Most CAPTCHA demo pages show you a puzzle and a green tick. They rarely show what matters: the verdict the vendor's server gives the site, and the invisible score behind it. Here you can see both.
Open the live measurement page
What you can play now
| What | What you see | Status (2026-11-03) |
|---|---|---|
| Google reCAPTCHA v3 | No puzzle. Your browser's score from 0.0 to 1.0, as Google's server returns it to the site | Live, real key |
| Google reCAPTCHA v2 tick box | The "I'm not a robot" box, sometimes a picture or audio challenge, then the server verdict | Live, real key |
| Cloudflare Turnstile | Usually no puzzle; whether Cloudflare's server accepts the token, and whether it asked you to click | Live, real key |
| ALTCHA | A proof-of-work check your browser computes; verified by our own server | Live, self-hosted |
| Cap | A proof-of-work check; verified by its own server, which we host | Live, self-hosted |
All five run on measure.captcharena.org with keys we own, on our own domain, and every token is checked by the vendor's own server (or, for the self-hosted ones, by the software's own verifier). The page stores no IP address and sets no cookie of ours. More about what the page measures: Browser score.
Coming next
Elsewhere on the web
- neal.fun "I'm Not a Robot", a comedy game of increasingly absurd CAPTCHA levels by Neal Agarwal (launched 2025-09-16). It "offers 0% security and 100% user annoyance", in its author's words on its embed page (checked 2026-11-01). It is a game, not a security check.
- Detection test pages that show what your browser reveals, such as EFF Cover Your Tracks and BrowserLeaks (checked 2026-11-01).
Rules every page here follows
- No practice puzzle ever imitates a real vendor's look, name or logo. Fake CAPTCHAs are a common malware lure, and we will not train people to trust lookalikes.
- No page here ever asks you to press a key combination, open a terminal, paste anything or download a file. If a "CAPTCHA" asks for that anywhere, it is an attack: how to spot a fake CAPTCHA.
Pages in Play: try real CAPTCHAs and see the server's verdict
- Practice puzzles: the open research puzzles we will host coming
Which open-source CAPTCHA research puzzles the Play section will host, under which licences, and how human and agent results will be compared.