# Delx Commerce X402 Payment Replay Key

> Delx Commerce X402 Payment Replay Key is a paid API for AI agents from commerce.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Generates a deterministic replay key from nonce, payer, and resource inputs for verifying and deduplicating x402 micropayments without retaining any data.

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/x402-payment-replay-key?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-commerce-x402-payment-replay-key-9fd3d128
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aXbOX7jDWNZEjzssjTFqc

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability delx-commerce-x402-payment-replay-key-9fd3d128 -d '<json body>'
```

Example prompt: Compute an x402 payment replay key for nonce 'abc123', payer '0xDeadBeef...', and resource '/api/v1/data' so I can verify this payment hasn't been replayed.

## When to prefer this

Use this endpoint when you need a lightweight, stateless, verifiable deduplication key for x402 protocol micropayments — particularly when you want in-memory-only computation with no server-side data retention and a cryptographically auditable SHA-256 input hash. Prefer this over custom hashing logic when operating within the x402/USDC-on-Base or Solana payment ecosystem.

## Known failure modes

- Missing required fields (nonce, payer, resource) result in a validation error
- Inputs exceeding 8192 characters may be rejected
- Malformed JSON body returns a parse error
- Network timeout or service unavailability returns a 5xx error

## How this service works

Pay-per-result APIs for agents. No signup. Exact price. Verifiable delivery. USDC on Base + Solana via x402.

## Output

Returns a deterministic 64-character hex replay key derived from the provided nonce, payer, and resource fields, along with the field list used, a SHA-256 hash of the input (for auditability), confirmation that no data was retained, and the operation name 'delivery_contract:x402_payment_replay_key'.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "nonce": {
   "type": "string",
   "maxLength": 8192,
   "description": "Nonce supplied to X402 Payment Replay Key; used only for this bounded calculation and processed in memory without retention."
  },
  "payer": {
   "type": "string",
   "maxLength": 8192,
   "description": "Payer supplied to X402 Payment Replay Key; used only for this bounded calculation and processed in memory without retention."
  },
  "resource": {
   "type": "string",
   "maxLength": 8192,
   "description": "Resource supplied to X402 Payment Replay Key; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "key": "e3cc8d847b2f88337939a2fab5ac3409aebfe27f223855a64805eba4ea53a947",
   "fields": [
    "nonce",
    "payer",
    "resource"
   ],
   "secret": false
  },
  "schema": "delx/util-x402-payment-replay-key/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "07fbf5ea1e08edc254770787f1273ba864ab5603eb570e42969f774e980e8a0e",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_payment_replay_key"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-x402-payment-replay-key-9fd3d128/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from commerce.delx.ai](https://www.zero.xyz/host/commerce.delx.ai/llms.txt)