# Web Freshness Fingerprint Observer

> Web Freshness Fingerprint Observer is a paid API for AI agents from 149-28-140-63.nip.io, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Fetches a public HTTP(S) URL and returns a timestamped SHA-256 content fingerprint along with HTTP metadata for change detection and verification.

## Facts

- Endpoint: POST https://149-28-140-63.nip.io/v1/execute/web.freshness
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/web-freshness-fingerprint-observer-fe3eb73f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7h1zQwtHFcq5gikzkoHC9

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 web-freshness-fingerprint-observer-fe3eb73f -d '<json body>'
```

Example prompt: Fetch https://example.com/terms-of-service and give me a timestamped SHA-256 fingerprint of its current content so I can tell if it changes later.

## When to prefer this

Choose this endpoint when you need a neutral, timestamped proof of what a public URL served at a specific moment — particularly for change detection pipelines, content integrity audits, or verifying that a resource matches a known fingerprint. Prefer it over manual HTTP fetching when you need structured metadata (status, final URL, content type, timestamp) alongside the hash in a single call.

## Known failure modes

- URL is unreachable or times out — service may return an error or non-200 status
- URL is private or requires authentication — returns a 401/403 status with limited metadata
- Redirect loops cause the fetch to fail — final_url may differ unexpectedly
- SSL/TLS certificate errors on HTTPS URLs may cause fetch failure
- Content is dynamically generated so SHA-256 differs on every fetch even without meaningful change
- Provided expected_sha256 does not match the observed hash — mismatch is surfaced in result

## How this service works

Pay-per-request agent service providing timestamped SHA-256 fingerprints of public HTTP(S) resources.

## Output

A JSON object containing the observed URL, its SHA-256 content fingerprint, HTTP status code, final URL (after any redirects), the ISO 8601 timestamp of observation, content type, and content length in bytes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Public HTTP(S) URL to observe."
  },
  "expected_sha256": {
   "type": "string",
   "description": "Optional expected SHA-256 fingerprint."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "url": "https://example.com",
   "sha256": "0000000000000000000000000000000000000000000000000000000000000000",
   "status": 200,
   "final_url": "https://example.com",
   "observed_at": "2026-01-01T00:00:00.000Z",
   "content_type": "text/html",
   "content_length": 1256
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/web-freshness-fingerprint-observer-fe3eb73f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 149-28-140-63.nip.io](https://www.zero.xyz/host/149-28-140-63.nip.io/llms.txt)