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EVM Calldata Decoder
x402
EVM Calldata Decoder 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).
Decodes raw EVM transaction calldata into human-readable function signatures and typed arguments
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
Returns a JSON object with ok=true, the tool name, and a result containing: the decoded function signature (e.g. 'approve(address,uint256)'), an array of typed arguments each with their EVM type and value, the 4-byte function selector, and the number of ABI candidates matched. Enables human-readable interpretation of raw EVM transaction data without needing a full ABI.
Example use cases
Auditing DeFi transaction calldata
“I have this raw calldata from a suspicious transaction: 0xa9059cbb000000000000000000000000deadbeef... — can you decode it to tell me what function is being called and what address and amount are in the arguments?”
Debugging smart contract interactions
“My Ethereum transaction failed and the input data is 0x23b872dd0000000000000000000000001234... — decode this calldata so I can see which function was invoked and check if the parameters look correct.”
Explaining wallet transaction to user
“A user is asking what this pending transaction in their wallet actually does — the calldata starts with 0x095ea7b3. Can you decode it and explain what function it's calling and what the typed arguments are?”
Technical details
Endpoint
POSThttps://x402-toolbox.swiftbotlab.workers.dev/v1/evm/calldata-decode?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need lightweight, pay-per-call EVM calldata decoding without setting up an account or managing API keys. Ideal for agents that occasionally need to interpret transaction input data on-the-fly. Prefer this over full node RPC calls or heavy blockchain indexers when you just need to decode a single calldata blob cheaply and quickly.
Side effects
- Malformed or non-hex calldata returns an error response
- Unrecognized 4-byte selector with no matching ABI candidates returns zero candidates or decoding failure
- Calldata exceeding 262144 bytes is rejected
- Payment not included or insufficient USDC payment causes HTTP 402 response
- Empty data field returns validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| data | string |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"tool": "calldata-decode",
"result": {
"decoded": {
"args": [
{
"type": "address",
"value": "0x2481E29895b43e87e547a50fB0BB5aa1E70585EB"
},
{
"type": "uint256",
"value": "115792089237316195423570985008687907853269984665640564039457584007913129639935"
}
],
"signature": "approve(address,uint256)"
},
"selector": "0x095ea7b3",
"candidates": 1
}
}
}Tags
x402
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