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Swift Bot Labs EVM Selector Lookup
x402
Swift Bot Labs EVM Selector Lookup is a paid API for AI agents from x402-toolbox.swiftbotlab.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-31).
Resolves EVM function selectors (4-byte) and event topics (32-byte) to their human-readable ABI signatures
Price / call$0.005
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 containing matched function signatures and event signatures for each queried selector. Each entry includes the selector/topic hash, a verified flag indicating whether the signature is confirmed, and the human-readable Solidity signature string (e.g. 'transfer(address,uint256)'). Multiple signature matches per selector are possible when collisions exist.
Example use cases
Decode transaction calldata selector
“I'm analyzing an Ethereum transaction and the calldata starts with 0x23b872dd — can you look up what function that selector maps to?”
Identify smart contract event topics
“I have these two event topic hashes from a contract log: 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef and 0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925 — what are their Solidity event signatures?”
Audit contract interaction signatures
“During a smart contract audit I found selectors 0x70a08231, 0xa9059cbb, and 0x095ea7b3 in the bytecode — can you resolve all three to their function signatures so I know what they do?”
Technical details
Endpoint
GEThttps://x402-toolbox.swiftbotlab.workers.dev/v1/evm/selector-lookup?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need fast, pay-per-use EVM selector and event topic resolution without setting up an account or API key. It supports batch lookups of multiple selectors in a single call and returns verification status alongside signatures. Prefer this over running a local Ethereum node or querying Etherscan's API when you need lightweight, deterministic decoding with USDC micropayment billing via x402.
Side effects
- Unknown selector returns empty results array for that hash rather than an error
- Malformed selector (wrong length, non-hex) may return a 400 error
- Selector not in the database returns ok:true with empty results for that selector
- Payment failure (x402) results in 402 response before lookup is attempted
- Network timeout on the Cloudflare Worker edge
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"tool": "evm-selector-lookup",
"result": {
"events": {
"0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef": [
{
"verified": true,
"signature": "Transfer(address,address,uint256)"
}
]
},
"functions": {
"0xa9059cbb": [
{
"verified": true,
"signature": "transfer(address,uint256)"
}
]
}
}
}
}Tags
x402
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