# Try It Live Below is a **real mini guestbook**. The verification widget is wired up to Capcat's **production service** running on Cloudflare Workers. Check the box and proof of work runs in the background of your browser; once it passes, the "Post message" button unlocks. On submit, the server first burns this cap-token through a real [`/siteverify`](https://capcat.ai/guide/siteverify.md) check — only then is your message stored. Messages are public, showing the latest 10 by default. > (An interactive demo lives here; the Markdown version cannot render it. Open https://capcat.ai/guide/demo.html in a browser to try it.) > (An interactive demo lives here; the Markdown version cannot render it. Open https://capcat.ai/guide/demo.html in a browser to try it.) ## What happens behind the scenes 1. The widget requests a challenge from the verification service, and the server issues a signed JWT. 2. Your browser solves two layers of challenge in the background: proof of work (solved in parallel across Web Workers), plus a dynamically generated browser instrumentation routine — confirming the solve happened in a real browser, not a script talking to the API directly (usually 1–3 seconds, entirely invisible to the user). 3. The solution is submitted back to the server for verification. Once it passes, a single-use `cap-token` is issued — your backend calls [`/siteverify`](https://capcat.ai/guide/siteverify.md) with it to complete the final confirmation, and the token is burned on use. The "Post message" button on this page performs that exact step: only when the burn succeeds is your message stored and shown in the list. > **Note** > > This demo uses the same configuration as the production site: PoW + instrumentation checks (including headless browser detection) are on by default, and can be tuned per site in the console. The guestbook is demo-only and keeps just the most recent messages. ## Scenario demos Want to see Capcat dropped into a real page? The [live demo](https://capcat.ai/demo/) collects three common scenarios, each gating a key action behind Capcat verification: - **Comments & messages** — the post button is locked until verification passes, instantly making spam-bot flooding uneconomical. - **Account signup** — every submission must first pay real compute cost and pass browser instrumentation, sharply cutting the throughput of bulk registration and credential-stuffing scripts. - **AI chat / expensive endpoints** — verification runs before the call, raising the cost of abusing the endpoint without getting in the way of real users. Ready to integrate Capcat into your own project? Head to [Quick Start](https://capcat.ai/guide/index.md) — it takes about 5 minutes.