# EVM Calldata Decoder via Openchain

> EVM Calldata Decoder via Openchain is a paid API for AI agents from 1c09pdnrx1.execute-api.us-east-1.amazonaws.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Decodes raw EVM calldata into a human-readable function name and typed parameters using openchain.xyz

## Facts

- Endpoint: POST https://1c09pdnrx1.execute-api.us-east-1.amazonaws.com/v1/decode/calldata
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-calldata-decoder-via-openchain-38ea06cc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FApLGtWNPGb0uYa_4Be9u

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 evm-calldata-decoder-via-openchain-38ea06cc -d '<json body>'
```

Example prompt: Can you decode this raw EVM calldata for me and tell me what function it's calling and what the parameters are: 0xa9059cbb000000000000000000000000ab5801a7d398351b8be11c439e05c5b3259aec9b0000000000000000000000000000000000000000000000000de0b6b3a7640000

## When to prefer this

Use this endpoint when you have raw hex calldata from an EVM transaction input and need to understand what function is being called and with what arguments. Prefer this over a full transaction decoder when you only have the calldata bytes (not a full tx hash) and need fast, targeted ABI decoding. Backed by openchain.xyz's extensive signature database for broad coverage.

## Known failure modes

- Unknown or unregistered function selector — openchain.xyz may not have the ABI for every contract, returning a not-found or unknown selector error
- Malformed calldata — if the hex string is not valid or too short, returns a parsing or validation error
- Calldata with no selector — bare bytes without a 4-byte selector cannot be decoded as a function call
- Rate limiting or upstream openchain.xyz unavailability — returns 5xx or timeout

## How this service works

Decode raw EVM calldata into function + typed params (GET wrapper) — $0.001 USDC

## Output

Returns the decoded function name, full function signature, and an array of typed parameters with their names, ABI types, and decoded values extracted from the calldata hex string.

## Example request

```json
{
 "chain": "ethereum",
 "calldata_hex": "0xa9059cbb000000000000000000000000ab5801a7d398351b8be11c439e05c5b3259aec9b0000000000000000000000000000000000000000000000000de0b6b3a7640000",
 "contract_address": null
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "title": "DatetimeParseRequest",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "string",
   "title": "Input",
   "maxLength": 500,
   "minLength": 1,
   "description": "Freeform datetime string in any format."
  },
  "timezone": {
   "type": "string",
   "title": "Timezone",
   "default": "UTC",
   "description": "IANA tz name (e.g. 'America/New_York')."
  },
  "base_time": {
   "anyOf": [
    {
     "type": "string"
    },
    {
     "type": "null"
    }
   ],
   "title": "Base Time",
   "description": "ISO 8601 reference; defaults to now UTC."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "params",
  "source",
  "decoded",
  "candidates",
  "function_name",
  "function_selector",
  "function_signature"
 ],
 "properties": {
  "params": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "name",
     "type",
     "value"
    ],
    "properties": {
     "name": {
      "type": "null"
     },
     "type": {
      "type": "string"
     },
     "value": {
      "type": "string"
     }
    }
   }
  },
  "source": {
   "type": "string"
  },
  "decoded": {
   "type": "boolean"
  },
  "candidates": {
   "type": "array",
   "items": {
    "type": "unknown"
   }
  },
  "function_name": {
   "type": "string"
  },
  "function_selector": {
   "type": "string"
  },
  "function_signature": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evm-calldata-decoder-via-openchain-38ea06cc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 1c09pdnrx1.execute-api.us-east-1.amazonaws.com](https://www.zero.xyz/host/1c09pdnrx1.execute-api.us-east-1.amazonaws.com/llms.txt)