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Kairostamp URL Digest Receipt
x402
Kairostamp URL Digest Receipt is a paid API for AI agents from kairostamp.com, paid per call via x402, $0.002/call, status down (last checked 2026-10-13).
Fetches a public URL server-side and returns a tamper-evident receipt containing HTTP status, final URL, content type, byte length, SHA-256 hash, redirect chain, and a hash-chain entry for audit integrity.
Price / call$0.002
Success—
StatusDown
How this service works
URL digest receipt: server-side fetch of one public http/https URL, returning a time-stamped receipt with the HTTP status, final URL, content type, byte length, SHA-256 of the response body, redirect chain, receipt id and tamper-evident hash-chain entry. Single GET query parameter (url). One call performs one fetch; there is no monitoring and no retry.
Output
Returns a JSON object containing: a UUID receipt_id, a fetched_at ISO timestamp, the final URL after redirects, HTTP status_code, content_type, byte_length, sha256 hash of the response body, an ordered redirect_chain array, an optional text_preview, a chain_hash (SHA-256 hash-chain entry linking this receipt to prior ones), and a previous_chain_hash for chain continuity verification.
Example use cases
Legal evidence of published content
“Fetch https://acme.com/press-release/acquisition-announcement.html right now and give me a timestamped receipt with the SHA-256 hash and receipt ID — I need to prove what was publicly posted at that URL today.”
File integrity checkpoint before processing
“Before I ingest this report, fetch https://data.gov/datasets/report-2024.csv and get me a digest receipt with the byte length, content type, and SHA-256 so I can confirm the file hasn't changed later.”
API response snapshot for audit log
“Hit https://api.partner.com/v2/pricing and capture a tamper-evident receipt showing the HTTP status, body hash, and timestamp — I need an audit trail of what price data they were serving this morning.”
Technical details
Endpoint
GEThttps://kairostamp.com/api/v1/digest?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a single-point-in-time cryptographic attestation of what a URL served — combining HTTP metadata, body hash, and a tamper-evident hash chain — rather than just checking liveness or extracting readable content. Prefer it over the sibling HTTP metadata endpoint when you need the SHA-256 body hash and hash-chain linkage for audit or legal purposes. Use it when the goal is to create verifiable evidence of a URL's content that can be independently verified via Kairostamp's receipt verification endpoint.
Side effects
- Non-public or authenticated URLs return an error since the server fetches without credentials
- Unreachable or offline URLs result in a connection error receipt
- URLs exceeding 2048 characters are rejected by schema validation
- Private/intranet URLs (e.g. localhost, 192.168.x.x) are likely blocked
- Malformed URL format returns a 400-level validation error
- Very large response bodies may time out or be truncated
Tags
x402
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