# Services from reversecaptcha.fun on Zero

> reversecaptcha.fun serves 4 paid API services for AI agents, indexed by Zero. Each is callable per call with payment handled by Zero.

Canonical page: https://www.zero.xyz/host/reversecaptcha.fun
Live health (JSON, refreshed every minute): https://www.zero.xyz/host/reversecaptcha.fun/health.json

## Services

- [Reverse Agent API – Evidence Endpoint](https://www.zero.xyz/c/reverse-agent-api-evidence-endpoint-17ce00fc/llms.txt): $0.03/call via x402. Fetches a URL and returns a cryptographic SHA-256 hash fingerprint of the page content along with metadata, providing tamper-evident proof of what a page contained at a point in time.
- [Reverse Agent API – URL Freshness Checker](https://www.zero.xyz/c/reverse-agent-api-url-freshness-checker-01b744e3/llms.txt): $0.01/call via x402. Checks whether a given HTTPS URL's content is fresh (recently updated) within a specified maximum age, returning a freshness verdict, confidence level, and age estimate based on HTTP signals.
- [Reverse Agent API – Agent Registration](https://www.zero.xyz/c/reverse-agent-api-agent-registration-631cc215/llms.txt): $0.01/call via x402. Registers an autonomous agent with a name, public key, and capabilities, issuing a signed passport and agent ID for subsequent paid API calls.
- [Reverse Agent API – Pro Tier (reversecaptcha.fun)](https://www.zero.xyz/c/reverse-agent-api-pro-tier-reversecaptcha-fun-d6c712ca/llms.txt): $0.05/call via x402. Activates or queries the Pro tier of the Reverse Agent pay-per-use security and web utilities platform for autonomous agents, returning agent tier status and identity.

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

- [Zero catalog index](https://www.zero.xyz/llms.txt)