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PreFlight – Decode TX Calldata
x402
PreFlight – Decode TX Calldata is a paid API for AI agents from meryol-agenticmarket-x402.hf.space, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).
Decodes EVM transaction calldata and flags red-flag patterns (e.g. unlimited approvals, unverified spenders) before an agent signs
Price / call$0.003
Success—
StatusUnknown
How this service works
Pre-trade & pre-sign checks for autonomous agents: everything an agent verifies BEFORE signing a transaction — token due diligence, calldata red-flag decoding, oracle freshness, holder concentration, bridge routing with executable calldata, cross-venue perp funding, gas and price sanity checks. EVM chains: Ethereum, Base, Arbitrum, Optimism.
Output
Returns the decoded function signature, selector, typed argument list (with types and values), a human-readable summary of what the transaction does, and an array of red-flag labels such as 'unlimited_token_approval' or 'approval_to_unverified_contract'.
Example use cases
Example prompt
“Before I sign this transaction, decode the calldata for me and flag any red flags — the contract is 0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48 on Ethereum and the calldata starts with 095ea7b3 approving 0xdeadbeef... for a max uint256 amount.”
Technical details
Endpoint
POSThttps://meryol-agenticmarket-x402.hf.space/decode/txWhen to prefer
Use this endpoint when an AI agent needs to understand and safety-check a raw EVM transaction before submitting it — especially for token approvals, DeFi interactions, or any calldata received from an untrusted source. Prefer this over generic ABI decoders when you need red-flag detection (unlimited approvals, unverified spenders) alongside decoding in a single pre-sign check.
Side effects
- Malformed or non-hex calldata returns a decode error
- Unknown function selector not in ABI database returns partial decode
- Unsupported chain identifier returns 400 validation error
- Network timeout or HuggingFace Space cold-start latency spike
- Payment not attached or insufficient USDC returns 402 error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
"args": [
{
"type": "address",
"value": "0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef"
},
{
"type": "uint256",
"value": "115792089237316195423570985008687907853269984665640564039457584007913129639935"
}
],
"chain": "ethereum",
"summary": "Approve spender 0xdeadbeef... to spend UNLIMITED on token USDC",
"selector": "095ea7b3",
"red_flags": [
"unlimited_token_approval",
"approval_to_unverified_contract"
],
"signature": "approve(address,uint256)"
}
}Tags
x402
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