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SignalHarness ABI Signature Selector
x402
SignalHarness ABI Signature Selector is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-13).
Resolves and returns ABI function/event signature selectors for a given Solidity ABI signature request string
Price / call$0.005
Success—
StatusUnknown
How this service works
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Output
Returns a JSON object with a `signature_selectors` field containing the resolved hex selector(s) for the provided ABI signature, along with any `warnings` about ambiguity or issues, the `service_id`, and `evidence_scope`. Also includes a full payment receipt with timing, payment ID, amount, network (Base), and a SHA256 hash of the result for verification.
Example use cases
Resolve ERC20 function selector
“Can you look up the ABI signature selector for `approve(address,uint256)` so I can construct the correct calldata for an ERC20 approve transaction?”
Identify event topic hash
“I need the keccak256 topic hash for the Solidity event `Transfer(address,address,uint256)` — can you resolve the ABI signature selector for it?”
Validate unknown calldata prefix
“I'm seeing a 4-byte prefix of `0xa9059cbb` in some raw transaction calldata — can you confirm what ABI function signature that selector corresponds to?”
Technical details
Endpoint
POSThttps://signalharness.ai/api/agent/services/abi_signature_selector/invokeWhen to prefer
Choose this endpoint when you need a fast, reliable resolution of Solidity ABI function or event signature selectors without running a local Ethereum node or relying on free public databases that may be incomplete. It is priced per-call at $0.005 USDC via x402 micropayment, making it suitable for agent workflows that need on-demand selector resolution without bulk subscription commitments.
Side effects
- Malformed or syntactically invalid ABI signature string returns error or empty selectors
- Ambiguous overloaded signatures may produce warnings
- Input string exceeding 65536 characters is rejected by schema validation
- Network or payment processing failure returns non-succeeded status
- Unknown or non-standard signature not in known databases may return no match
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| abi_signature_request | string |
Output
Schema · Response
{
"type": "json",
"example": {
"replay": false,
"result": {
"warnings": [
"Selectors alone do not prove an interface is implemented."
],
"service_id": "abi_signature_selector",
"evidence_scope": "caller_supplied_data",
"signature_selectors": "{\"kind\":\"function\",\"selectors\":[{\"selector\":\"0x70a08231\",\"signature\":\"balanceOf(address)\"},{\"selector\":\"0xa9059cbb\",\"signature\":\"transfer(address,uint256)\"}]}"
},
"status": "succeeded",
"receipt": {
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"usage": [],
"status": "succeeded",
"network": "eip155:8453",
"artifacts": [],
"endedAtMs": 0,
"latencyMs": 0,
"paymentId": "example-payment",
"receiptId": "example-receipt",
"requestId": "example-request",
"serviceId": "abi_signature_selector",
"executionId": "example-execution",
"startedAtMs": 0,
"amountAtomic": "5000",
"resultSha256": "2985fc2ce0e1ecaffce7ea49fbebe23b6adda9e99e9042990c1b32bda229d377",
"serviceVersion": "1.0.0",
"settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
},
"artifacts": [],
"requestId": "example-request",
"executionId": "example-execution"
}
}Tags
x402
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