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X402 Idempotency Check
x402
X402 Idempotency Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-20).
Compares payment and delivery idempotency keys for an x402 operation to detect duplicates and verify keys match before accepting or paying for agent-delivered results.
Price / call$0.001
Success—
StatusUnknown
How this service works
X402 Idempotency Check: X402 Idempotency Check compares payment and delivery idempotency keys for one operation from bounded caller-supplied values without an external provider. Call X402 Idempotency Check before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for X402 Idempotency Check as versioned deterministic…
Output
Returns an explicit acceptance or rejection status for the operation, contract-specific validation checks, normalized evidence from the provided keys, and any mismatch reasons detected between the payment and delivery idempotency keys.
Example use cases
Guard against duplicate x402 payments
“I'm about to pay for an x402 result — can you check the payment key 'pay_a1b2c3' and delivery key 'del_c3b2a1' to make sure this isn't a duplicate and the keys actually match?”
Validate agent delivery before acceptance
“Before my agent accepts this delivery, verify that the payment idempotency key 'pay_qwerty123' and the delivery idempotency key 'del_qwerty456' are aligned and there's no mismatch reason flagged.”
Audit x402 operation key consistency
“Can you run an idempotency check on these two keys from an x402 operation — payment key 'pay_zz9900ff' and delivery key 'del_zz9900ff' — and tell me whether they're accepted or rejected and why?”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/x402-idempotency-check?utm_source=zero.xyzWhen to prefer
Use this endpoint when operating in the x402 payment protocol ecosystem and needing a deterministic, stateless check that payment and delivery idempotency keys correspond before committing to a payment or accepting an agent result. Prefer this over custom key comparison logic when you need normalized evidence and explicit accept/reject verdicts with mismatch explanations included.
Side effects
- Missing or empty payment_key or delivery_key fields causes validation failure
- Keys exceeding 8192 character limit are rejected
- Mismatched keys return rejection status with detailed mismatch reasons
- Malformed or non-string key values may result in error response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| payment_key | string | Payment Key supplied to X402 Idempotency Check; used only for this bounded calculation and processed in memory without retention. |
| delivery_key | string | Delivery Key supplied to X402 Idempotency Check; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"matched": true,
"payment_key": "job-42",
"delivery_key": "job-42"
},
"schema": "delx/util-x402-idempotency-check/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "a9aa562b36a16cb899fdccfd5bcae9beef661bc9955a23c2dab0076b08c36ff5",
"external_calls": 0
},
"operation": "delivery_contract:x402_idempotency_check"
}
}Tags
x402
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