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Base Calldata Decoder
x402
Base Calldata Decoder is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).
Decodes raw Ethereum calldata on Base network, identifying the function name, selector, and decoded arguments from ABI-encoded transaction input data.
Price / call$0.01
Success—
StatusUnknown
How this service works
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Output
Returns a JSON object containing the decoded function name, function selector (e.g. '0xa9059cbb'), decoded argument values, total calldata byte size, Base network context (accepted chain IDs, deposit transaction type, fee model, protocol family), evidence scope, and any warnings if the supplied ABI may be incorrect. Also includes a full receipt with payment ID, execution ID, and result hash.
Example use cases
Debug a failed smart contract call
“I have this raw calldata from a failed Base transaction: 0xa9059cbb000000000000000000000000abc...0064 — can you decode it and tell me what function it was trying to call and with what arguments?”
Inspect an ERC20 token transfer
“Can you decode this calldata from a Base network token transfer and tell me the recipient address and amount being sent? Here's the hex input: 0xa9059cbb0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000006400”
Audit a DeFi transaction before signing
“Before I sign this transaction, can you decode the calldata so I can confirm what function it's calling and verify the arguments look right? The calldata is 0x23b872dd000000000000000000000000abc...”
Technical details
Endpoint
POSThttps://signalharness.ai/api/agent/services/base_calldata_decode/invokeWhen to prefer
Choose this endpoint when you need to decode raw EVM calldata specifically on the Base network (chain IDs 8453 or 84532) and want structured output including function name, selector, and arguments. Prefer this over manual ABI decoding when you need quick, pay-per-call access without managing your own node or ABI libraries. Ideal for agents auditing transactions, debugging failed calls, or inspecting DeFi interactions on Base.
Side effects
- Invalid or malformed calldata hex string returns a decoding error
- Unknown function selector with no ABI provided may result in undecodable output or warnings
- Calldata too long (exceeding 65536 character limit) will be rejected
- Empty or null request_json will fail schema validation
- Non-Base calldata from other networks may decode incorrectly due to network context assumptions
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| request_json | string |
Output
Schema · Response
{
"type": "json",
"example": {
"replay": false,
"result": {
"warnings": [
"A supplied ABI may be incorrect and decoding does not simulate execution."
],
"service_id": "base_calldata_decode",
"analysis_json": "{\"args\":[\"0x0000000000000000000000000000000000000002\",\"100\"],\"calldata_bytes\":68,\"function_name\":\"transfer\",\"network_context\":{\"accepted_chain_ids\":[\"8453\",\"84532\"],\"deposit_transaction_type\":\"0x7e\",\"fee_model\":\"L2 execution plus caller-supplied L1 data/operator components\",\"protocol_family\":\"OP Stack\"},\"selector\":\"0xa9059cbb\"}",
"evidence_scope": "caller_supplied_data",
"analyzed_network": "base"
},
"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": "base_calldata_decode",
"executionId": "example-execution",
"startedAtMs": 0,
"amountAtomic": "10000",
"resultSha256": "beff1ae8843f8360a1951a55a31040e9fd3afa3b3da6a0927148c1c534263835",
"serviceVersion": "1.0.0",
"settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
},
"artifacts": [],
"requestId": "example-request",
"executionId": "example-execution"
}
}Tags
x402
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