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Crypto Calldata Decoder (x402)
x402
Crypto Calldata Decoder (x402) is a paid API for AI agents from kr-x402-mvp.kgy5612.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).
Decodes raw EVM calldata or a Base transaction hash into human-readable function name, arguments, risk verdict, and security flags — paid per call via x402 USDC micropayment.
Price / call$0.002
Success—
StatusUnknown
How this service works
Pay-per-call crypto microdata for trading/onchain AI agents via x402 (USDC on Base): Base gas, token risk, balances, multi-venue prices, Hyperliquid book/funding, kimchi premium. No API keys.
Output
Returns the decoded function name and selector, typed argument list with values, a risk verdict (e.g. CAUTION/OK/DANGER), security flags (e.g. unlimited_approval), a plain-English summary of what the call does, a spender label if recognized, and guidance on next steps. Also indicates whether the approval is unlimited and identifies the target token symbol/decimals when a contract address is supplied.
Example use cases
Safe approval check before signing
“I'm about to sign an approve transaction on Base. Can you decode this calldata — 0x095ea7b3000000000000000000000000000000000022d473030f116ddee9f6b43ac78ba3ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff — for the contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 and tell me whether it's granting unlimited allowance and to whom?”
Investigate suspicious Base transaction
“I just saw a tx on Base with hash 0x4a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b — can you decode what it actually did and flag any risky behavior like unlimited approvals or suspicious spenders?”
Agent pre-flight calldata validation
“Before my DeFi bot submits this calldata on Base, decode 0xa9059cbb000000000000000000000000abcdef1234567890abcdef1234567890abcdef12000000000000000000000000000000000000000000000000002386f26fc10000 targeting 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 and confirm what function it's calling, the recipient, and the amount being transferred.”
Technical details
Endpoint
GEThttps://kr-x402-mvp.kgy5612.workers.dev/api/chain/decode?utm_source=zero.xyzWhen to prefer
Use this endpoint when an AI agent or user needs to understand what a raw EVM calldata blob or Base transaction actually does before signing or broadcasting — especially for security screening of token approvals, transfers, and DeFi interactions. Prefer this over generic block explorers when you need structured, machine-readable risk verdicts and labeled spender identification in a pay-per-call, no-API-key flow on Base.
Side effects
- Invalid or malformed calldata hex returns a decode error
- Unknown function selector not in built-in or 4byte database returns partial decode with unknown function name
- Unrecognized Base tx hash returns not-found error
- Missing required 'data' or 'hash' parameter returns 400 validation error
- Payment failure via x402 (insufficient USDC balance) blocks the call
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"args": [
{
"type": "address",
"value": "0x000000000022D473030F116dDEE9F6B43aC78BA3"
},
{
"type": "uint256",
"value": "115792089237316195423570985008687907853269984665640564039457584007913129639935"
}
],
"risk": "medium",
"chain": "base",
"flags": [
"unlimited_approval"
],
"amount": "unlimited",
"spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
"summary": "lets Uniswap Permit2 move ALL USDC from the signer",
"verdict": "CAUTION",
"function": "approve(address,uint256)",
"guidance": "Review the decoded args; simulate with /crypto/base-rpc?method=eth_call before signing.",
"selector": "0x095ea7b3",
"unlimited": true,
"spender_label": "Uniswap Permit2",
"signature_source": "builtin"
}
}Tags
x402
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