# FreshProof HTTP API

> FreshProof HTTP API is a paid API for AI agents from freshproof-http.ricardobessellp-11d.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-02).

Fetches a public URL and returns a timestamped SHA-256 fingerprint of the response body, proving what content was served at a specific moment in time.

## Facts

- Endpoint: POST https://freshproof-http.ricardobessellp-11d.workers.dev/observe?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/freshproof-http-api-0d25f25c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KQsUBFbWaZomdfPvqfUor

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 freshproof-http-api-0d25f25c -d '<json body>'
```

Example prompt: Get me a fresh SHA-256 fingerprint of https://example.com/terms-of-service right now — force a new network request so I have a timestamped proof of exactly what that page contains today.

## When to prefer this

Choose FreshProof when you need cryptographically verifiable, timestamped proof of what a public URL served at a specific moment — particularly for auditing, compliance, content integrity checks, or dispute resolution. It is ideal when you need to prove a page said something at a given time, detect content drift over repeated observations, or create an immutable audit trail. Prefer max_age=0 when freshness is critical. Use over generic HTTP clients when the timestamped SHA-256 fingerprint and machine-to-machine payment via x402 are required as part of the workflow.

## Known failure modes

- URL is not publicly reachable — network error or timeout returned
- URL returns a non-200 status (e.g. 403, 404, 500) — status is recorded but may not represent expected content
- shared_cache result returned when max_age > 0 and a recent observation already exists — may not reflect the very latest content
- Payment failure or insufficient USDC balance — request rejected before observation is made
- URL redirects to a private or internal address — may fail or return unexpected content
- Response body too large — may cause timeout or truncation in the fingerprint

## How this service works

Paid machine-to-machine public URL observations with timestamped SHA-256 response-body fingerprints. POST /observe costs $0.005 USDC per call on Base via x402 v2. The price is the same for shared_cache and fresh_fetch results. A fresh_fetch means FreshProof performed a new public-network HTTP request at the recorded time. The destination itself may serve content from its own CDN, proxy, or cache.

## Output

A JSON object containing: the observed URL and final URL after redirects, HTTP status code, source ('fresh_fetch' or 'shared_cache'), SHA-256 content hash of the response body, ISO 8601 observed_at timestamp, age_seconds, content_length in bytes, fetch_duration_ms, and optional ETag and Last-Modified headers if present.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "description": "Public HTTP or HTTPS URL to observe"
  },
  "max_age": {
   "type": "integer",
   "minimum": 0,
   "description": "Maximum acceptable observation age in seconds. Defaults to 300. Set to 0 to force a fresh public-network request."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://example.com",
  "etag": null,
  "source": "fresh_fetch",
  "status": 200,
  "final_url": "https://example.com/",
  "age_seconds": 0,
  "observed_at": "2026-09-23T10:00:00.000Z",
  "content_hash": "sha256:ff67a9d764d6a2367a187734e697f6a53217db9a21c101d410a113ca871a299d",
  "last_modified": null,
  "content_length": 559,
  "fetch_duration_ms": 8
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/freshproof-http-api-0d25f25c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from freshproof-http.ricardobessellp-11d.workers.dev](https://www.zero.xyz/host/freshproof-http.ricardobessellp-11d.workers.dev/llms.txt)