# Delx Commerce X402 Scheme Select

> Delx Commerce X402 Scheme Select 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).

Selects the best matching X402 payment scheme from a list of schemes against a set of supported schemes, returning the chosen scheme with verifiable evidence.

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/x402-scheme-select?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-scheme-select-a67d3287
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EW2MfEIoGJRL6tE1olUXR

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-scheme-select-a67d3287 -d '<json body>'
```

Example prompt: Given my available x402 payment schemes ['exact','flexible'] and the server's supported schemes ['exact'], figure out which scheme we should use to proceed with this payment.

## When to prefer this

Use this endpoint when your agent needs to programmatically negotiate the correct X402 payment scheme before initiating a micropayment, particularly when interacting with servers that advertise multiple scheme options and you need a deterministic, verifiable selection with cryptographic evidence of the input — without retaining sensitive data server-side.

## Known failure modes

- No matching scheme found between offered and supported lists — returns error or empty selection
- Malformed or empty schemes arrays — may return validation error
- Exceeding maxItems (256) per array — request rejected
- Non-string scheme values — schema validation failure

## 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 JSON object with the selected scheme name, a list of supported schemes, a status ('pass'), and a verifiable evidence block containing a SHA-256 hash of the input, a flag confirming no data retention, and a count of zero external calls made during processing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "schemes": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Schemes supplied to X402 Scheme Select; used only for this bounded calculation and processed in memory without retention."
  },
  "supported_schemes": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Supported Schemes supplied to X402 Scheme Select; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "selected": "exact",
   "supported": [
    "exact"
   ]
  },
  "schema": "delx/util-x402-scheme-select/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "a045739927a7259d237f0c405b73130cd2fb17caabdca6ce41cffff6ac4ff2ed",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_scheme_select"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-x402-scheme-select-a67d3287/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)