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Kairostamp Change Check
x402
Kairostamp Change Check is a paid API for AI agents from kairostamp.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).
Fetches a public URL server-side, compares its response body against a prior SHA-256 or Kairostamp receipt, and returns whether the content changed along with a new tamper-evident timestamped evidence receipt.
Price / call$0.01
Success—
StatusUnknown
How this service works
Kairostamp change check: server-side fetch of one public http/https URL, compared against a caller-supplied prior SHA-256 or prior Kairostamp receipt id. Returns whether the response body changed, both digests, and a new time-stamped evidence receipt with its tamper-evident hash-chain entry. One call performs one check; repeat monitoring means calling again.
Output
Returns a JSON object indicating whether the response body changed (boolean), the current SHA-256 digest of the fetched page, the prior SHA-256 digest used for comparison, a new Kairostamp evidence receipt with a UUID receipt ID, a timestamp, and a tamper-evident hash-chain entry linking this check to the prior receipt or hash.
Example use cases
Legal document change detection
“Has the privacy policy at https://acmecorp.com/privacy changed since we audited it? Here's the SHA-256 we recorded last month: d4e5f6a7b8c9012345678901234567890123456789012345678901234567890f — give me a receipt I can attach to our compliance log.”
Supplier price list drift monitoring
“Check if the public price list at https://supplier.example.com/prices.json has changed from the snapshot we captured yesterday — the prior receipt ID is 3fa85f64-5717-4562-b3fc-2c963f66afa6. I need to know if anything shifted.”
Regulatory filing verification
“Verify whether the SEC filing page at https://sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001234567 still matches the hash we recorded: 9b2e1f3a4c5d678901234567890123456789012345678901234567890123bcde, and produce a tamper-evident receipt as evidence.”
Technical details
Endpoint
POSThttps://kairostamp.com/api/v1/change-check?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need both a change-detection answer and a cryptographic, tamper-evident audit trail in a single call. It is ideal for compliance monitoring, legal evidence gathering, or automated alerting workflows where you need a hash-chain receipt proving the state of a URL at a specific moment. Prefer it over simple diff tools or basic polling when tamper-evident provenance matters, or when you already have a prior Kairostamp receipt ID and want to chain evidence. For first-time snapshots with no prior baseline, use the sibling URL digest receipt endpoint first.
Side effects
- URL is not publicly reachable or returns an error status — check fails with a fetch error
- URL uses a non-http/https scheme — rejected as invalid input
- Neither prior_sha256 nor prior_receipt_id supplied — request rejected
- Both prior_sha256 and prior_receipt_id supplied simultaneously — request rejected with conflict error
- prior_receipt_id refers to an unknown or expired receipt — lookup failure
- URL returns a redirect to a private or non-routable address — blocked for security
- Response body too large to hash within timeout — fetch timeout error
Tags
x402
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