# propeller.rocks EVM Calldata Encoder

> propeller.rocks EVM Calldata Encoder is a paid API for AI agents from propeller.rocks, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Encodes a function call (given a signature or ABI plus arguments) into EVM-compatible calldata bytes

## Facts

- Endpoint: GET https://propeller.rocks/encode/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/propeller-rocks-evm-calldata-encoder-c65ad2f7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cXMpDW9m8VFFPZ3_gDGxK

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 propeller-rocks-evm-calldata-encoder-c65ad2f7
```

Example prompt: Encode the EVM calldata for a call to transfer(address,uint256) with recipient 0xAbCd1234... and amount 1000000000000000000 — give me the hex calldata I can paste into a raw transaction.

## When to prefer this

Use this endpoint when you need to construct raw EVM calldata for a contract interaction and don't have a full Ethereum library (like ethers.js or web3.py) available in your agent environment. Ideal for lightweight agents that need to prepare transaction data for a smart contract call without spinning up a full SDK.

## Known failure modes

- Invalid or malformed function signature returns an error
- Mismatched argument types vs. signature returns encoding error
- Missing required arguments causes a 400 bad request
- ABI JSON is malformed or missing the function definition
- Argument values that can't be coerced to the expected Solidity types fail with a type error
- Payment not provided or insufficient balance returns a 402 Payment Required

## How this service works

Encode a function call (signature or abi + args) into EVM calldata

## Output

Returns ABI-encoded EVM calldata as a hex string representing the full function call, ready to be used as the data field in an Ethereum transaction or low-level contract call.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/propeller-rocks-evm-calldata-encoder-c65ad2f7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from propeller.rocks](https://www.zero.xyz/host/propeller.rocks/llms.txt)