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ABI Function Call Encoder (Calldata Generator)
x402
ABI Function Call Encoder (Calldata Generator) is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-16).
Encodes a Solidity function signature and its arguments into ABI-encoded calldata (selector + hex data) ready for signing or simulating on-chain.
Price / call$0.003
Success—
StatusUnknown
How this service works
Encode a contract function call (calldata) from its signature and arguments, e.g. transfer(address,uint256) with [to, amount]: selector and hex data ready to sign or simulate.
Output
Returns a JSON object containing: the canonical function signature string, the 4-byte function selector (e.g. 0xa9059cbb), the full ABI-encoded calldata hex string including selector and encoded arguments, and the total byte length of the calldata.
Example use cases
ERC-20 transfer calldata generation
“Encode calldata for transfer(address,uint256) with recipient 0xAbc123...def and amount 500000 — I need the selector and full hex to build a raw transaction.”
DeFi protocol interaction encoding
“Give me the ABI-encoded calldata for approve(address,uint256) with spender 0xUniswapRouter and amount 9999999999 so I can simulate the approval before signing.”
Smart contract simulation prep
“I want to simulate a swap on-chain — can you encode swapExactTokensForTokens(uint256,uint256,address[],address,uint256) with arguments [1000, 950, [0xTokenA, 0xTokenB], 0xMyWallet, 1716230400] into calldata?”
Technical details
Endpoint
POSThttps://api.vextorium.com/abi-codificar-pago?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to quickly generate raw EVM calldata from a function signature string and typed arguments without running a local ethers.js/web3.py library or a full node. Ideal for lightweight agent pipelines that need to prepare transaction data, simulate calls, or pass calldata to a signing service without setting up a local ABI encoding stack.
Side effects
- Invalid or malformed function signature returns an error
- Wrong number or type of arguments relative to signature causes encoding failure
- Unsupported Solidity types in the signature may not be handled
- Malformed Ethereum address argument causes a parsing error
- Empty or missing 'funcion' field returns a validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| funcion | string | |
| argumentos | array |
Output
Schema · Response
{
"type": "json",
"example": {
"bytes": 68,
"funcion": "transfer(address,uint256)",
"calldata": "0xa9059cbb0000000000000000000000007e5f4552091a69125d5dfcb7b8c2659029395bdf00000000000000000000000000000000000000000000000000000000000f4240",
"selector": "0xa9059cbb"
}
}Tags
x402
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