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SALT19 Commerce Receipt Verifier
x402
SALT19 Commerce Receipt Verifier is a paid API for AI agents from api.salt19.com, paid per call via x402, $0.04/call, status unknown (last checked 2026-09-15).
Verifies and issues a cryptographically signed receipt for an x402 micropayment transaction, confirming payment settlement and delivery against policy constraints.
Price / call$0.04
Success—
StatusUnknown
How this service works
SALT19 is an independent applied AI systems lab behind EvoMind governed cognition, the MCP-native Agent Utility Grid, the ARCS research community, AeroClear UAS flight intelligence, and practical software for real-world work.
Output
A JSON object containing a signed receipt with a unique receipt ID, a signing key ID, a verification URL (at api.salt19.com/proof402/receipts/), the signature algorithm (Ed25519), a verdict string (e.g. VERIFIED_LOCAL_EVIDENCE), and a commerce root hash attesting to the transaction.
Example use cases
Auditing agent micropayment compliance
“My AI agent just paid for a data lookup using x402 — can you verify the payment against my spend policy (max 500000 atomic units per transaction, USDC only, no blocked payees) and return a signed receipt I can store for compliance audits?”
Confirming paid content delivery
“I paid for a file via x402 and got a payload back — verify the payment was legitimate, check the delivered content matches the expected SHA256 hash, and give me a SALT19-signed receipt proving I received what I paid for.”
Enforcing per-day spend limits for an agent fleet
“My agent fleet is making x402 payments autonomously — after each payment, validate it against a 24-hour rolling spend cap of 10000000 atomic units and issue a signed receipt so I can track every transaction's verification status.”
Technical details
Endpoint
POSThttps://api.salt19.com/v1/commerce-receiptWhen to prefer
Use this endpoint when you need a cryptographically signed, auditable receipt for an x402-protocol micropayment — especially when operating autonomous agents that must enforce spend policies, verify content delivery integrity via SHA256, or produce compliance records. Prefer this over generic payment webhooks or off-chain confirmations when you need Ed25519-attested proof with a publicly verifiable URL hosted by SALT19.
Side effects
- Payment payload does not satisfy the provided policy (blocked payee, disallowed asset, or exceeded spend limit) — returns a rejection verdict
- Invalid or malformed x402Version (only version 2 is accepted) — validation error
- Expected SHA256 hash does not match delivered content — delivery verification failure
- Target operation ID is missing or too short (minimum 8 characters) — schema validation error
- Policy spend_24h_atomic or max_amount_atomic value is not a valid numeric string — request rejected
- Accepts array in payment_required is empty or exceeds 16 items — schema constraint violation
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| policy | object | |
| request | object | |
| delivery | — | |
| settlement | object | |
| payment_payload | object | |
| payment_required | object | |
| expected_delivery | object | |
| target_salt19_operation_id | string |
Output
Schema · Response
{
"type": "json",
"example": {
"receipt": {
"id": "...",
"signing_key_id": "...",
"verification_url": "https://api.salt19.com/proof402/receipts/...",
"signature_algorithm": "Ed25519"
},
"verdict": "VERIFIED_LOCAL_EVIDENCE",
"commerce_root": "..."
}
}Tags
x402
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