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FreshProof Compare
x402
FreshProof Compare is a paid API for AI agents from freshproof-api-mainnet.up.railway.app, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).
Fetches a live copy of a public URL and compares it against a previously stored FreshProof snapshot, returning deterministic fact differences, content hashes, and significance scores.
Price / call$0.02
Success—
StatusUnknown
How this service works
Compare a fresh public web retrieval with previous evidence from a ProofBundle or retained snapshot. Returns deterministic fact differences, evidence, content hashes, retrieval timestamps, and significance for autonomous agents without inventing unsupported changes.
Output
Returns a structured object containing deterministic fact differences (added, removed, or changed facts), content hashes for both the fresh retrieval and the previous snapshot, retrieval timestamps, evidence backing each difference, and a significance score indicating how materially the content has changed.
Example use cases
Detecting product price changes
“Compare the current Amazon listing at https://www.amazon.com/dp/B09XYZ1234 against my stored snapshot 1a2b3c4d-1234-4abc-a123-abcdef123456 and tell me if the price or availability has changed.”
Auditing a public policy document
“Fetch the latest version of https://example.gov/privacy-policy and diff it against snapshot f47ac10b-58cc-4372-a567-0e02b2c3d479 — I need to know exactly which facts or clauses were added, removed, or changed.”
Monitoring a competitor's homepage
“Pull the current version of https://competitor.com and compare it to my retained proof snapshot 550e8400-e29b-41d4-a716-446655440000 so I can see if they've updated their pricing, features, or messaging since last week.”
Technical details
Endpoint
POSThttps://freshproof-api-mainnet.up.railway.app/v1/compareWhen to prefer
Choose this endpoint when you need a deterministic, evidence-backed diff between a live web page and a previously captured FreshProof snapshot. It is ideal for autonomous agents that must audit factual changes without hallucinating or inferring unsupported differences. Prefer it over generic scraping or summarization tools when reproducibility, content hashing, and verifiable evidence are required — especially for compliance, monitoring, or fact-checking workflows where provenance matters.
Side effects
- Snapshot ID not found or expired — returns 404-equivalent with error indicating unknown snapshotId
- Target URL is unreachable or returns non-200 — returns error with retrieval failure details
- URL pattern validation failure if URL is malformed or non-HTTP/HTTPS
- Payment not included or insufficient — returns 402 Payment Required
- Rate limiting or timeout on the target URL causes partial or failed retrieval
- ProofBundle format mismatch causing comparison failure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Public HTTP or HTTPS URL to retrieve for fresh comparison. |
| previous | object | Previous evidence supplied as a ProofBundle or retained snapshot identifier. |
Output
Schema · Response
{
"type": "json",
"example": {
"changed": true,
"warnings": [],
"addedFacts": [],
"currentHash": "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
"previousHash": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
"removedFacts": [],
"modifiedFacts": [
{
"name": "price",
"newValue": {
"amount": 24.99,
"currency": "USD"
},
"oldValue": {
"amount": 19.99,
"currency": "USD"
},
"newEvidence": {
"quote": "USD 24.99",
"locator": "Freshly retrieved product price evidence",
"sourceUrl": "https://example.com/"
},
"oldEvidence": {
"quote": "USD 19.99",
"locator": "Previous retained product price evidence",
"sourceUrl": "https://example.com/"
},
"significance": "material"
}
],
"currentSnapshotId": "8b267630-834b-46c8-8e70-b7ca7cc54e28",
"currentRetrievedAt": "2026-07-28T08:30:00.000Z",
"highestSignificance": "material",
"previousRetrievedAt": "2026-07-27T08:30:00.000Z"
}
}Tags
x402
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