# Reverse Agent API – Evidence Endpoint

> Reverse Agent API – Evidence Endpoint is a paid API for AI agents from reversecaptcha.fun, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-23).

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.

## Facts

- Endpoint: POST https://reversecaptcha.fun/v1/paid/evidence?utm_source=zero.xyz
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/reverse-agent-api-evidence-endpoint-17ce00fc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kYckjdUqP2I19n0wKlWqf

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

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability reverse-agent-api-evidence-endpoint-17ce00fc -d '<json body>'
```

Example prompt: Fetch https://example.com/terms-of-service and give me a SHA-256 fingerprint of the page along with the title and timestamp so I have tamper-evident proof of what it contains right now.

## When to prefer this

Choose this endpoint when you need cryptographically verifiable, timestamped evidence of a webpage's contents — for audit trails, compliance documentation, content integrity checks, or proving what a URL contained at a specific moment. It is distinct from simple web scrapers because it returns a SHA-256 hash suitable for tamper-evident archiving, not just raw HTML or parsed text.

## Known failure modes

- Non-HTTPS URLs are rejected by schema validation (must start with https://)
- Target URL returns non-200 status — status field reflects this but ok may be false
- Target URL is unreachable or times out — request fails with error
- Redirects to a non-HTTPS final URL may cause issues
- Payment failure via x402 protocol prevents the call from completing

## How this service works

Reverse Agent API by reverse.captcha — pay-per-use security and web utilities for autonomous agents.

## Output

A JSON object with: `ok` (boolean success flag), `title` (page title string), `sha256` (hex SHA-256 hash of the page content), `status` (HTTP status code returned by the target URL), `final_url` (resolved URL after any redirects), and `fetched_at` (ISO 8601 timestamp of when the fetch occurred).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "pattern": "^https://"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "title": "Example Domain",
  "sha256": "...",
  "status": 200,
  "final_url": "https://example.com/",
  "fetched_at": "2026-01-01T00:00:00.000Z"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/reverse-agent-api-evidence-endpoint-17ce00fc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from reversecaptcha.fun](https://www.zero.xyz/host/reversecaptcha.fun/llms.txt)