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Contract Check
x402
Contract Check is a paid API for AI agents from x402-echo-service.onrender.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Determines whether a Base blockchain address is a smart contract or an externally owned account (EOA), returning bytecode size and keccak-256 hash.
Price / call$0.001
Success—
StatusUnknown
How this service works
Determine whether an address on Base is a contract or an externally owned account. POST {"address":"0x..."} and receive isContract, the bytecode size in bytes and its keccak-256 hash. Useful before sending funds to an unfamiliar address.
Output
Returns a JSON object with: isContract (boolean indicating whether the address has deployed code), bytecodeSize (integer, size of the code in bytes — 0 for EOAs), and a keccak-256 hash of the bytecode for contract fingerprinting.
Example use cases
Pre-transfer address safety check
“I'm about to send 2 ETH to 0xAbCd1234567890abcdef1234567890abcdef5678 — can you tell me if it's a smart contract or a plain wallet on Base before I do?”
DeFi integration contract validation
“Can you confirm that 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Base is actually a deployed smart contract and give me its bytecode size and code hash?”
Suspicious address investigation
“Someone sent me a payment request from 0xdeadbeef1234567890abcdef1234567890abcd12 on Base — is that address a contract or a real wallet? I want to know its bytecode details before I interact with it.”
Technical details
Endpoint
POSThttps://x402-echo-service.onrender.com/chain/codeWhen to prefer
Use this endpoint when you need to quickly classify a Base address as a contract or EOA before sending funds, interacting programmatically, or auditing an address. Prefer this over a general block explorer lookup when you need machine-readable output (isContract boolean, bytecode size, code hash) for automated decision-making in an agent workflow.
Side effects
- Invalid or malformed Ethereum address returns an error response
- Address with no on-chain activity may return isContract: false with size 0
- Network connectivity issues with the Base RPC may cause timeouts
- Self-destructed contracts may return isContract: false even if formerly deployed
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| address | string |
Tags
x402
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