# HTTP Policy Evidence Checker

> HTTP Policy Evidence Checker is a paid API for AI agents from x402-url-evidence.vercel.app, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Sends a POST, PUT, or PATCH request to a given URL and returns evidence of the HTTP response policy (HTTPS status, final URL after redirects, observed headers).

## Facts

- Endpoint: POST https://x402-url-evidence.vercel.app/api/http-policy
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/http-policy-evidence-checker-4865c4c6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hGjmzVx-DegzGx84SpLtn

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 http-policy-evidence-checker-4865c4c6 -d '<json body>'
```

Example prompt: Can you probe https://api.example.com/submit with a POST request and a JSON body containing {"url": "https://api.example.com/submit"} to check whether it uses HTTPS, what status code it returns, and how many response headers it sends back?

## When to prefer this

Use this endpoint when you need deterministic, paid evidence of HTTP policy for a specific URL — particularly when you need to confirm HTTPS usage, trace redirects on non-GET requests, or audit response header counts for POST/PUT/PATCH endpoints. Prefer this over browser-based or GET-only tools when you specifically need to test write-method HTTP behavior with a JSON, form-data, or text body.

## Known failure modes

- Target URL is unreachable or times out — may return a network error or non-200 status
- URL does not accept POST/PUT/PATCH — returns 405 Method Not Allowed
- Malformed input schema (missing required fields like 'url', 'type', 'method', 'bodyType') — returns validation error
- Target URL returns unexpected content type — may produce parsing issues
- Payment not settled — x402 payment required error before request is processed

## How this service works

Paid deterministic utility APIs settled in native USDC on Base.

## Output

Returns a JSON object confirming whether the target URL uses HTTPS (boolean), the HTTP status code received, the final URL after any redirects, and the count of observed response headers.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "https": true,
  "status": 200,
  "finalUrl": "https://example.com/",
  "observedHeaderCount": 3
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/http-policy-evidence-checker-4865c4c6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-url-evidence.vercel.app](https://www.zero.xyz/host/x402-url-evidence.vercel.app/llms.txt)