{"uid":"cap_hRpgxN4244WcMQ-a4Yy-r","slug":"base-onchain-data-address-inspector-eb534bf8","name":"Base Onchain Data - Address Inspector","description":"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.","url":"https://onchaincheck.dev/base/contract?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["address"],"properties":{"address":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","description":"Any address on Base"}},"additionalProperties":false}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"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"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_iItuk0QM2rW5YB-Ihpgkt","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"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.","exampleAgentPrompt":"Can you tell me what's at Base address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 — is it a wallet or a contract, and if it's a token what standard does it use, its name and symbol, and whether it's an upgradeable proxy?","exampleUseCases":[{"title":"Token due diligence before DeFi interaction","prompt":"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?"},{"title":"Distinguish wallet from contract in a transfer","prompt":"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?"},{"title":"Verify NFT collection contract on Base","prompt":"I want to verify that 0xd4307e0acd12cf46fd6cf93bc264f5d5d1598792 on Base is actually an ERC-721 NFT contract and get its collection name and symbol."}],"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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).","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T12:37:49.551Z","isFirstParty":false,"canonicalSlug":"base-onchain-data-address-inspector-eb534bf8"}