# Delx Commerce — EVM Transaction Selector Extractor

> Delx Commerce — EVM Transaction Selector Extractor is a paid API for AI agents from commerce.delx.ai, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).

Extracts the 4-byte ABI function selector and remaining calldata byte count from raw EVM transaction calldata hex.

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/selector-extract?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-commerce-evm-transaction-selector-extractor-73a3c068
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WSsa3sycUgTKHRAAu4_Te

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-evm-transaction-selector-extractor-73a3c068 -d '<json body>'
```

Example prompt: Can you extract the function selector from this EVM transaction calldata: 0xa9059cbb000000000000000000000000ab5801a7d398351b8be11c439e05c5b3259aec9000000000000000000000000000000000000000000000000000000003b9aca00 — I want to know which function it's calling and how many bytes of parameters follow.

## When to prefer this

Use this endpoint when you need a lightweight, pay-per-use, no-signup way to programmatically extract and validate the ABI function selector from raw EVM transaction calldata. It is ideal for blockchain agents, transaction monitoring pipelines, and smart contract auditing tools that need to quickly identify which Solidity function a raw hex payload targets without spinning up a local EVM decoder. Prefer it over full node RPC calls or heavy decoding libraries when you only need the selector and byte count in a single fast API call.

## Known failure modes

- Malformed or non-hex calldata string returns valid:false
- Calldata shorter than 4 bytes cannot yield a selector
- Missing 'calldata' field in request body causes validation error
- Payment failure via x402 protocol prevents execution
- Truncated calldata may return a selector but incorrect remaining_bytes count

## 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 a validity boolean, a schema identifier string (e.g. 'delx/util-selector-extract/v1'), the extracted 4-byte function selector as a hex string (e.g. '0xa9059cbb'), and the count of remaining bytes after the selector in the calldata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "calldata": {
   "type": "string",
   "description": "Transaction calldata hex; first 4 bytes are the selector."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "valid": true,
  "schema": "delx/util-selector-extract/v1",
  "selector": "0xa9059cbb",
  "remaining_bytes": 32
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-evm-transaction-selector-extractor-73a3c068/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)