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FreshProof HTTP API
x402
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 2026-10-01).
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.
Price / call$0.005
Success—
StatusUnknown
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.
Example use cases
Audit a public policy page
“Fetch https://acme.com/privacy-policy and give me a cryptographic fingerprint of what it contains today — I need a timestamped SHA-256 hash as proof of the current version, so use a max_age of 0 to make sure it's a fresh fetch.”
Monitor a live API endpoint for changes
“Check https://api.partner.com/v1/status for me and return a SHA-256 hash of the response body — use a max_age of 60 seconds so I can compare it against the hash I recorded an hour ago and see if anything changed.”
Certify a public file's content at a moment in time
“I need a verified observation of https://releases.myproject.io/latest/manifest.json — grab it fresh and give me the SHA-256 hash, observed timestamp, and final URL so I can attach this as evidence to our compliance report.”
Technical details
Endpoint
POSThttps://freshproof-http.ricardobessellp-11d.workers.dev/observe?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Public HTTP or HTTPS URL to observe |
| max_age | integer | Maximum acceptable observation age in seconds. Defaults to 300. Set to 0 to force a fresh public-network request. |
Output
Schema · Response
{
"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
}
}Tags
x402
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