{"slug":"base-token-check-fly-dev-v1-counterparty-check-c93e36","title":"Check a Base address before an agent pays or approves it","host":"base-token-check.fly.dev","method":"GET","resource":"https://base-token-check.fly.dev/v1/counterparty-check","category":"code","description":"Check a Base address before an agent pays or approves it. Input: one address. Output: allow or warn. Reports wallet or contract, whether the wallet has sent a transaction, whether a contract already had code 7 days ago, and whether it is a proxy (EIP-1967, EIP-1167, or implementation()). Warns on co","price_listed":0.01,"price_asked":0.01,"state":"answering","state_label":"Answering","checks_7d":1,"answered_7d":1,"latency_ms_median":418,"reported_calls_30d":2,"reported_payers_30d":1,"networks":["eip155:8453"],"badge":"unverified","paid_checks_7d":0,"paid_ok_7d":0,"example_input":{"method":"GET","queryParams":{"address":"0x540c2aA2526C9c8c2fb4632f0fED668C36424Cd5"},"type":"http"},"output_schema":{"$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"input":{"additionalProperties":false,"properties":{"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"queryParams":{"properties":{"address":{"description":"Wallet or contract on Base to check before paying or approving it.","pattern":"^0x[0-9a-fA-F]{40}$","type":"string"}},"required":["address"],"type":"object"},"type":{"const":"http","type":"string"}},"required":["type","method"],"type":"object"},"output":{"properties":{"example":{"type":"object"},"type":{"type":"string"}},"required":["type"],"type":"object"}},"required":["input"],"type":"object"},"history":[{"day":"2026-10-10","reachable":true,"status":402,"valid_402":true,"asked_usdc":0.01,"price_match":true,"latency_ms":418,"error":null}],"description_full":"Check a Base address before an agent pays or approves it. Input: one address. Output: allow or warn. Reports wallet or contract, whether the wallet has sent a transaction, whether a contract already had code 7 days ago, and whether it is a proxy (EIP-1967, EIP-1167, or implementation()). Warns on contract_is_new, proxy, or no_outgoing_transactions. Wallet age is unknown. A deleted contract looks like a wallet. Not proof of theft.","last_updated":"2026-10-04T21:41:18.542Z","schemes":["exact"]}