# 402oracle.com URL Freshness Verifier

> 402oracle.com URL Freshness Verifier is a paid API for AI agents from 402oracle.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-13).

Checks whether a URL is live and its content is current by returning HTTP status, caching headers, a SHA-256 content hash, and a signed attestation indicating whether the content changed since a prior check.

## Facts

- Endpoint: POST https://402oracle.com/verify/freshness
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/402oracle-com-url-freshness-verifier-522344c4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8f0nrGlQF47KeTI6rlytR

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 402oracle-com-url-freshness-verifier-522344c4 -d '<json body>'
```

Example prompt: Before you summarize that report, can you check if https://example.com/annual-report-2024.pdf is still live and whether its content has changed since the SHA-256 hash abc123def456 I got last week?

## When to prefer this

Choose this endpoint when your agent needs cryptographic assurance that a URL is live and its content is current or unchanged before taking an action that depends on it — such as approving a payment, summarizing a document, or citing a source. The signed attestation makes this especially valuable in agentic pipelines where you need auditable proof of content state. Prefer this over a simple HTTP HEAD check when content-change detection and signed provenance are required.

## Known failure modes

- URL is unreachable or returns a non-200 status (4xx/5xx) — attestation reflects the error status
- Network timeout when fetching the target URL — may return an error or timeout indicator
- URL redirects to a login page or paywall, resulting in a hash of the redirect destination rather than intended content
- No prior hash provided — change detection cannot be performed, only current state returned
- Invalid URL format submitted — request rejected with validation error

## How this service works

Check that a URL is live and its data is fresh before your agent acts on its contents. A freshness oracle: returns HTTP status, Last-Modified/ETag, a content SHA-256, and whether the content changed versus a prior hash. Returns a signed attestation.

## Output

Returns the HTTP status code of the URL, Last-Modified and ETag caching headers if available, a SHA-256 hash of the current content, a boolean indicating whether the content changed relative to a previously provided hash, and a cryptographically signed attestation of the result.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Full URL including https://"
  },
  "prior_hash": {
   "type": "string",
   "description": "Optional prior SHA-256 hex to compare against"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "signature": {
   "alg": "ES256",
   "jwks": "/.well-known/jwks.json"
  },
  "attestation": {
   "type": "freshness_verification",
   "result": {
    "status": 200,
    "changed": false,
    "reachable": true,
    "content_sha256": "9f86d081884c7d65"
   },
   "subject": {
    "url": "https://example.com/data.json"
   },
   "confidence": 0.98
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/402oracle-com-url-freshness-verifier-522344c4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 402oracle.com](https://www.zero.xyz/host/402oracle.com/llms.txt)