{"uid":"cap_ns6zgg95K0_iCJQDAbzY3","slug":"erc-20-allowance-checker-on-base-4639a151","name":"ERC-20 Allowance Checker on Base","description":"ERC-20 approval check on Base: how much can spender move from owner? owner=0x..&spender=0x..[&token=0x.., default USDC][&amount=] -> allowance, unlimited flag, owner balance, exposure (min of allowance and balance), known spender label (Permit2, Uniswap, 1inch, 0x, Odos, Aerodrome), risk class, revoke_recommended + ready approve(spender,0) calldata, can_spend when amount= given. Use before transferFrom/swap, or to audit a wallet's dangerous approvals.","url":"https://kr-x402-mvp.kgy5612.workers.dev/crypto/allowance?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["owner","spender"],"properties":{"owner":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","examples":["0xe4be4d0bd82d8e68203deff81f79ede0529f2617"],"description":"Token holder (alias wallet)"},"token":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","examples":["0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"],"description":"Base ERC-20 (default USDC)"},"amount":{"type":"number","examples":[1],"description":"Optional amount to test can_spend"},"spender":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","examples":["0x000000000022D473030F116dDEE9F6B43aC78BA3"],"description":"Approved spender / router"}},"additionalProperties":false}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"risk":"none","block":53250000,"chain":"base","owner":"0xe4be4d0bd82d8e68203deff81f79ede0529f2617","token":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","symbol":"USDC","spender":"0x000000000022D473030F116dDEE9F6B43aC78BA3","decimals":6,"exposure":0,"allowance":0,"revoke_tx":null,"unlimited":false,"allowance_raw":"0","owner_balance":0.079,"spender_label":"Uniswap Permit2","revoke_recommended":false}},"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_PseI-v5SN2Da_jxQqsSxG","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":"Checks how much of an ERC-20 token a spender is approved to move from an owner's wallet on Base, with risk classification, exposure calculation, and ready-to-use revoke calldata.","exampleAgentPrompt":"Before I do this swap, check how much USDC spender 0x000000000022D473030F116dDEE9F6B43aC78BA3 is approved to move from my wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 on Base, and tell me if it's risky or if I should revoke it.","exampleUseCases":[{"title":"Pre-swap approval safety check","prompt":"Before I execute this Uniswap swap, check if the Permit2 contract 0x000000000022D473030F116dDEE9F6B43aC78BA3 already has enough USDC allowance from my wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 to move 500 USDC, and whether that approval is risky."},{"title":"Wallet approval security audit","prompt":"Audit the USDC allowance that the Odos router 0xa669e7A0d4b3e4Fa48af2dE86BD4CD7126Be4e1 has on my wallet 0xabc1234000000000000000000000000000000001 — tell me the exposure, risk class, and give me revoke calldata if I should cancel it."},{"title":"Detect unlimited token approval","prompt":"Check if I accidentally gave unlimited USDC approval to the 1inch contract 0x1111111254EEB25477B68fb85Ed929f73A960582 from my wallet 0xdef0000000000000000000000000000000000002 on Base, and if so, give me the calldata to revoke it."}],"resultDescription":"A JSON object containing: current allowance (raw and human-readable), whether it is unlimited, owner's token balance, the effective exposure (min of allowance and balance), the known label for the spender (e.g. Uniswap Permit2, 1inch, Odos), a risk class (none/low/medium/high), whether revocation is recommended, ready-to-use approve(spender,0) calldata for revocation, can_spend boolean when amount is provided, and the block number at which the data was fetched.","failureModes":["Invalid owner or spender address format (not a 0x hex address) returns 400 error","Unknown or non-ERC-20 token address may return error or zero values","RPC timeout or Base node unavailability causes 503 or delayed response","Missing required owner or spender parameters returns 400","Amount parameter as non-numeric value causes validation error","Payment not sent or insufficient USDC balance returns 402"],"whenToPreferThis":"Use this endpoint when your agent needs to verify ERC-20 token approvals on Base before executing swaps or transfers, or when auditing a wallet for dangerous unlimited approvals. It is purpose-built for Base with labeled spender recognition (Permit2, Uniswap, 1inch, 0x, Odos, Aerodrome) and includes pre-computed revoke calldata, making it faster than calling the blockchain directly. Prefer it over generic RPC calls when you need risk classification, exposure analysis, and actionable remediation in a single call.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-31T18:41:58.670Z","isFirstParty":false,"canonicalSlug":"erc-20-allowance-checker-on-base-4639a151"}