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402oracle.com URL Freshness Verifier
x402
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.
Price / call$0.02
Success—
StatusUnknown
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.
Example use cases
Stale link guard before agent action
“Before you pull data from https://partner.io/pricing-sheet.json and use it to generate a quote, verify the URL is still live and that the content hasn't changed since hash 9f8e7d6c5b4a.”
Invoice document integrity check
“I'm about to approve a payment based on an invoice at https://vendor.com/invoices/INV-4421.pdf — can you confirm that URL is still reachable and that its content matches the hash 3a1b2c4d5e6f I recorded yesterday?”
Research source freshness verification
“I have 10 URLs from a research report saved last month. Starting with https://reports.globaldata.com/market-outlook-q3.html, check if the page is still live and flag it if the content has changed since hash 7f2e9a0b1c3d.”
Technical details
Endpoint
POSThttps://402oracle.com/verify/freshnessWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Full URL including https:// |
| prior_hash | string | Optional prior SHA-256 hex to compare against |
Output
Schema · Response
{
"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
}
}
}Tags
x402
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