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Base Onchain Data - Address Inspector
x402
Base Onchain Data - Address Inspector is a paid API for AI agents from onchaincheck.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).
Identifies what lives at a Base blockchain address: EOA wallet, smart contract type, token standard (ERC-20/721/1155), name, symbol, proxy info, bytecode size, nonce, and ETH balance.
Price / call$0.005
Success—
StatusUnknown
How this service works
Identify what lives at a Base address: wallet (EOA, including EIP-7702 delegation) or contract, which token standard it implements (ERC-20, ERC-721, ERC-1155), name and symbol, upgradeable-proxy implementation and admin, smart-wallet proxies, bytecode size, nonce and ETH balance.
Output
Returns a JSON object with: address, chain ('base'), kind (e.g. 'ERC-20 token', 'EOA', 'smart contract'), name, symbol, decimals, totalSupply, nativeBalance (ETH), bytecodeBytes, nonce, isContract flag, standards object (erc20/erc165/erc721/erc1155 booleans), and proxy details (upgradeable boolean, implementation address, admin address) when applicable.
Example use cases
Token due diligence before DeFi interaction
“Before I approve this token on Base at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913, can you tell me if it's a legitimate ERC-20, what its name and symbol are, whether it's an upgradeable proxy, and who controls the admin?”
Distinguish wallet from contract in a transfer
“I'm about to send ETH to 0x4fc7850364958d97B4d3f5A08f79db2493f8cA44 on Base — can you check whether that's a plain wallet or a smart contract, and if it's a contract what kind it is?”
Verify NFT collection contract on Base
“I want to verify that 0xd4307e0acd12cf46fd6cf93bc264f5d5d1598792 on Base is actually an ERC-721 NFT contract and get its collection name and symbol.”
Technical details
Endpoint
GEThttps://onchaincheck.dev/base/contract?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a comprehensive one-shot classification of any Base address — whether it's a wallet or contract, what token standard it implements, proxy admin/implementation details, and current ETH balance. Prefer it over generic block explorers when you need structured, machine-readable output suitable for agent pipelines. Use it for due diligence before DeFi interactions, verifying token contracts, or resolving unknown addresses on Base specifically (not Ethereum mainnet or other L2s).
Side effects
- Invalid address format (not a 42-character 0x hex string) — likely 400 error
- Address not found or zero activity on Base — may return minimal data
- Proxy detection may be incomplete for non-standard proxy patterns
- RPC timeout or Base node unavailability — service error
- Payment failure via x402 protocol — 402 response if USDC balance insufficient
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"kind": "ERC-20 token",
"name": "USD Coin",
"chain": "base",
"proxy": {
"admin": "0x4fc7850364958d97B4d3f5A08f79db2493f8cA44",
"upgradeable": true,
"implementation": "0x2Ce6311ddAE708829bc0784C967b7d77D19FD779"
},
"symbol": "USDC",
"address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"decimals": 6,
"standards": {
"erc20": true,
"erc165": false,
"erc721": false,
"erc1155": false
},
"isContract": true,
"totalSupply": "4291989037.45169",
"bytecodeBytes": 1852,
"nativeBalance": "0.009800646158085843"
}
}Tags
x402
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