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Swift Bot Labs EVM Function Selector Calculator
x402
Swift Bot Labs EVM Function Selector Calculator is a paid API for AI agents from x402-toolbox.swiftbotlab.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-31).
Computes the 4-byte EVM function selector and 32-byte topic hash from a Solidity function signature string
Price / call$0.003
Success—
StatusUnknown
How this service works
62 small, deterministic utility APIs (DNS and e-mail checks, web extraction, EVM decoding, x402 checks, IP math, JSON/CSV, hashing, conversions). No account or API key: pay per call in USDC with x402.
Output
A JSON object with ok:true, the tool name 'evm-selector', and a result containing the 4-byte hex function selector (e.g. 0xa9059cbb), the 32-byte keccak256 topic hash (0x...), and the canonical normalized form of the input signature.
Example use cases
Decode unknown calldata in transaction
“I'm looking at an Ethereum transaction and the calldata starts with 0xa9059cbb — can you tell me what the selector and canonical signature are for transfer(address,uint256) so I can confirm it matches?”
Build smart contract ABI tooling
“I'm writing a script that needs the 4-byte selector and keccak256 topic hash for the Solidity function approve(address,uint256) — can you compute those for me?”
Verify event topic hash for log filtering
“I need to filter Ethereum logs for Transfer events. What's the 32-byte topic hash and selector for Transfer(address,address,uint256) so I can set up the right filter?”
Technical details
Endpoint
GEThttps://x402-toolbox.swiftbotlab.workers.dev/v1/evm/selector?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, deterministic, pay-per-call computation of an EVM function selector or topic hash without setting up an account or SDK. Ideal for one-off lookups in agent workflows or scripts that occasionally need ABI encoding without a full Ethereum node or library dependency.
Side effects
- Invalid or malformed Solidity signature string returns an error
- Missing required 'signature' query parameter returns a validation error
- Payment failure or insufficient USDC balance blocks the call with a 402 response
- Ambiguous or non-canonical type names may produce unexpected selectors
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"tool": "evm-selector",
"result": {
"topic": "0x...",
"selector": "0xa9059cbb",
"canonical": "transfer(address,uint256)"
}
}
}Tags
x402
Reviews
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