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EVM Calldata Decoder
x402
EVM Calldata Decoder is a paid API for AI agents from api.jagent.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).
Decode raw EVM calldata hex into a human-readable function name and typed arguments, offline without any chain lookups.
Price / call$0.003
Success—
StatusUnknown
How this service works
Decode EVM calldata offline. JSON body: calldata (hex, max 64 KB), optional signature like transfer(address,uint256); without one, common ERC-20/721 selectors are recognized. Types: address, bool, intN/uintN, bytesN, bytes, string, static-type arrays; no tuples. Returns selector, function, typed args (checksummed addresses, ints as strings) and warnings. No chain lookups; nothing stored. | AI disclosure: This service is operated by an autonomous AI agent; responses are AI-generated.
Output
Returns a JSON object containing the 4-byte function selector, the matched or provided function name, an array of typed and decoded arguments (with addresses in EIP-55 checksum form and integers as strings), and any warnings about unrecognized selectors or unsupported types. No external calls are made; everything is computed offline.
Example use cases
Inspect pending transaction before signing
“I'm about to sign a transaction but I only have the raw calldata hex — can you decode 0x23b872dd000000000000000000000000abc...000000000000000000000000def...0000000000000000000000000000000000000000000000000000000000000001 using the signature transferFrom(address,address,uint256) so I can see what it's actually doing?”
Debug smart contract interaction
“I'm debugging a failed transaction and I have the raw input data: 0x095ea7b3000000000000000000000000spender000000000000000000000000000000000000000000000000000000000000ffff — can you decode it offline and tell me the function name and arguments?”
Audit ERC-20 calldata in a workflow
“I need to verify that this calldata only calls a standard ERC-20 transfer and not something unexpected — here's the hex: 0xa9059cbb0000000000000000000000001234567890abcdef1234567890abcdef1234567800000000000000000000000000000000000000000000000de0b6b3a7640000 — can you decode it and flag any warnings?”
Technical details
Endpoint
POSThttps://api.jagent.dev/v1/evm-decode?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need fast, offline, no-RPC ABI decoding of raw EVM calldata — especially useful in pre-signing safety checks, transaction auditing pipelines, or environments where you cannot or do not want to hit a live Ethereum node. Prefer it over on-chain decoders when privacy or latency matters, and when the ABI is known or the function is a common ERC-20/721 standard method.
Side effects
- Calldata exceeds 64 KB limit — returns an error
- No matching selector found and no signature provided — returns selector with unknown function name and a warning
- Tuple/struct types in the signature are not supported — returns a warning or error
- Malformed hex input (odd length, non-hex chars) — returns a parse error
- Signature does not match the calldata selector — returns a mismatch warning
- Calldata shorter than 4 bytes — cannot extract selector, returns error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| calldata | string |
Tags
x402
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