{"uid":"cap_yUA4IzOf0goU_Jmin55ZP","slug":"erc-20-allowance-lookup-bb3bb2ae","name":"ERC-20 Allowance Lookup","description":"How much a spender is approved to move from an owner — Genesis402 / UnyKorn Operator Network","url":"https://twin.unykorn.org/erc20-allowance?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"params":{"type":"object","properties":{"chain":{"enum":["ethereum","base","polygon","arbitrum","optimism","bsc","avalanche","gnosis","linea","scroll"],"type":"string"},"owner":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$"},"spender":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$"},"contract":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$"}}}}},"responseSchema":{"type":"json","example":{"ok":true,"type":"erc20-allowance","receipt":{"tx_hash":"0x<64hex>","amount_usd":0.003,"receipt_id":"g402-<16hex>"},"generated_at":"<iso8601>"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.003","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":"$0.003/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_vDanSu8LZRHhhrL_u7NLq","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.003","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns how much a spender address is approved to transfer from an owner's ERC-20 token balance on a given EVM chain","exampleAgentPrompt":"What's the current ERC-20 allowance that the Uniswap router (0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45) is approved to spend from my wallet (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B) for USDC (0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) on Ethereum?","exampleUseCases":[{"title":"Pre-swap approval check on a DEX","prompt":"Before I do a swap on Arbitrum, can you check whether the SushiSwap router (0x1b02dA8Cb0d097eB8D57A175b88c7D8b47997506) has enough allowance to spend my WETH (0x82aF49447D8a07e3bd95BD0d56f35241523fBab1) from my wallet (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B)?"},{"title":"DeFi lending protocol approval audit","prompt":"I want to know how much the Aave v3 pool contract (0x794a61358D6845594F94dc1DB02A252b5b4814aD) is allowed to move from my address (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B) for USDC (0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174) on Polygon."},{"title":"Security check for unknown approval","prompt":"I think I may have approved a suspicious contract (0xDeadBeef12345678901234567890123456789012) to spend my DAI (0x6B175474E89094C44Da98b954EedeAC495271d0F) on Ethereum — can you look up the current allowance from my wallet (0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B) to that address?"}],"resultDescription":"Returns a JSON object with ok status, the allowance type identifier, and a receipt containing a transaction hash, the USD cost of the call ($0.003), and a unique receipt ID — confirming how many tokens the spender is approved to move from the owner for the given ERC-20 contract on the specified chain.","failureModes":["Invalid Ethereum address format for owner, spender, or contract (must be 0x + 40 hex chars)","Unsupported chain name — only ethereum, base, polygon, arbitrum, optimism, bsc, avalanche, gnosis, linea, scroll are accepted","RPC node unavailable for the requested chain","Payment failure via x402 protocol (insufficient USDC balance)","Contract address is not a valid ERC-20 token"],"whenToPreferThis":"Use this endpoint when you need to programmatically check the current ERC-20 spending allowance between two specific addresses on any of 10 supported EVM chains without running your own node. It is ideal for pre-transaction approval validation, DeFi workflow automation, and security auditing of token approvals. It is preferable when you need a pay-per-call, no-subscription approach via the x402 protocol.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T03:54:12.806Z","isFirstParty":false,"canonicalSlug":"erc-20-allowance-lookup-bb3bb2ae"}