Decode transaction calldata API

Decode raw EVM transaction calldata into its function name and arguments using the free OpenChain signature database — no ABI needed. Answers queries like 'what does this calldata do', 'decode this transaction input', 'what function is this hex calling'.

Price$0.01per request

MethodPOST

Route/v1/evm/decode-calldata

StatusLive

MIME typeapplication/json

Rate limit90/minute

CacheNo cache

evmcalldatadecodetransactionfunction-selector4byteabi

API URLhttps://x402.hexl.dev/v1/evm/decode-calldata

Integration docs

Example request

{
  "data": "0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000de0b6b3a7640000"
}

Example response

{
  "selector": "0xa9059cbb",
  "signature": "transfer(address,uint256)",
  "functionName": "transfer",
  "args": [
    "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "1000000000000000000"
  ],
  "candidates": [
    "transfer(address,uint256)"
  ]
}

Input schema

{
  "type": "object",
  "required": [
    "data"
  ],
  "properties": {
    "data": {
      "type": "string",
      "pattern": "^0x[0-9a-fA-F]{8,}$"
    }
  }
}

Output schema

{
  "type": "object",
  "required": [
    "selector",
    "candidates"
  ],
  "properties": {
    "selector": {
      "type": "string"
    },
    "signature": {
      "type": [
        "string",
        "null"
      ]
    },
    "functionName": {
      "type": [
        "string",
        "null"
      ]
    },
    "args": {
      "type": [
        "array",
        "null"
      ],
      "items": {
        "type": "string"
      }
    },
    "candidates": {
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "note": {
      "type": "string"
    }
  }
}