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Immuta Seal – On-Chain Document Notarization
x402
Immuta Seal – On-Chain Document Notarization is a paid API for AI agents from api.immuta.app, paid per call via x402, $1/call, status unknown (last checked 2026-09-13).
Notarizes a SHA-256 hash on the blockchain, creating a permanent, independently verifiable timestamp proof that a document existed at a specific moment.
Price / call$1
Success—
StatusUnknown
How this service works
Notarize a document on-chain: permanent, independently verifiable proof that a SHA-256 hash existed at this moment. Send only the hash - the document never leaves your system. Returns a blockchain transaction receipt.
Output
Returns a blockchain transaction receipt confirming the hash has been permanently anchored on-chain, including the transaction hash, block number, timestamp, and network details — providing independently verifiable proof that the given SHA-256 hash existed at that exact moment.
Example use cases
Legal contract timestamp proof
“I've just finalized a contract and need to prove it existed as of today. The SHA-256 hash of the PDF is a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3 — can you seal that on-chain for me?”
Intellectual property authorship record
“I've written a new piece of software and want to establish that I authored it before I file for a patent. The SHA-256 of my source archive is 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 — please notarize it on the blockchain right now.”
Audit trail for compliance evidence
“We're required to demonstrate that our compliance report wasn't altered after submission. Hash is 9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08 — seal it on-chain so we have an immutable timestamped record for our auditors.”
Technical details
Endpoint
POSThttps://api.immuta.app/sealWhen to prefer
Choose this endpoint when you need a cryptographically secure, blockchain-anchored timestamp proving a document or file existed at a specific moment — without ever transmitting the document itself. Ideal for legal evidence, IP authorship records, compliance audit trails, or any workflow requiring tamper-proof, independently verifiable proof of existence. Prefer this over centralized notarization services when trustlessness and decentralization matter.
Side effects
- Invalid or malformed SHA-256 hash format — returns 400 Bad Request
- Insufficient USDC balance or payment failure — transaction not submitted
- Blockchain network congestion causing delayed confirmation
- Duplicate hash submission — may succeed but creates a second on-chain record
- Network timeout before transaction is mined — receipt may not be returned even if transaction was broadcast
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| note | string | Optional note stored on-chain (up to 500 bytes) |
| label | string | Short label stored on-chain with the record (1-100 bytes) |
| sha256 | string | SHA-256 hash (64 hex chars) of the document to notarize. Compute locally; do not send the document. |
Tags
x402
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