{"uid":"cap_ySbAwS032EXdCB3CbImU9","slug":"erc-20-allowance-checker-on-base-3f3cf1d8","name":"ERC-20 Allowance Checker on Base","description":"Is a token approval already granted? Returns the ERC-20 allowance an owner gave a spender on Base, raw and formatted, and flags unlimited approvals ($0.002 per call).","url":"https://api.api-agent-ia.ch/allowance?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$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","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","required":["token","owner","spender"],"properties":{"owner":{"type":"string"},"token":{"type":"string"},"spender":{"type":"string"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"owner":"0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045","token":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","reseau":"base","symbol":"USDC","spender":"0x000000000022D473030F116dDEE9F6B43aC78BA3","decimals":6,"illimitee":false,"allowance_brut":"0","allowance_formate":"0"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","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":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_LXjsUkoIxOyyyK_4DXLcP","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns the ERC-20 token allowance a spender is approved to use from an owner's wallet on Base mainnet, flagging unlimited approvals.","exampleAgentPrompt":"Before I do this swap, can you check how much USDC (0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) my wallet 0xAbCd...1234 has approved the Uniswap router 0x3fC9...5678 to spend on Base?","exampleUseCases":[{"title":"Pre-swap approval check for DeFi","prompt":"I'm about to swap USDC for ETH on a Base DEX — can you check if my wallet 0xAbCd...1234 has already approved the router contract 0x3fC9...5678 to spend USDC at 0xd9aA...ef01 on Base, and tell me how much is approved?"},{"title":"Detect unlimited token approval risk","prompt":"Can you check whether my address 0xBEEF...cafe has granted an unlimited approval to the contract 0xDEAD...beef for the USDT token 0x4200...0006 on Base? I want to know if I should revoke it."},{"title":"Audit DeFi protocol allowances before interaction","prompt":"Before I deposit into this lending protocol at 0x1234...abcd, check if my wallet 0x5678...dcba already has an approval set for DAI token 0x50c5...725D on Base so I don't have to approve again."}],"resultDescription":"Returns a JSON object containing the owner address, token address, token symbol, spender address, and the formatted allowance amount the spender is approved to use. Unlimited approvals are flagged with a special indicator.","failureModes":["Invalid 0x address format for token, owner, or spender returns an error","Token address is not a valid ERC-20 contract on Base returns an error or zero allowance","Network issues with Base RPC may cause timeouts","Querying an address with no approval returns allowance of 0"],"whenToPreferThis":"Use this endpoint when you need to check an existing ERC-20 token approval on Base mainnet before initiating a DeFi transaction such as a swap, deposit, or transfer. It is ideal for pre-flight checks in DeFi automation agents to avoid unnecessary on-chain approval transactions. Prefer this over general blockchain explorers when you want a structured, agent-consumable response with formatted allowance and unlimited-approval detection.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-24T12:31:36.643Z","isFirstParty":false,"canonicalSlug":"erc-20-allowance-checker-on-base-3f3cf1d8"}