{"uid":"cap_zgE0tQyItOw47FKWGJTb4","slug":"erc-20-token-allowance-lookup-1cd1ae5e","name":"ERC-20 Token Allowance Lookup","description":"Machine-payable data APIs for AI agents — 35 endpoints across web search, on-chain reads, trading data, and AI-visibility. Pay per call in USDC via x402 on Base. No API keys, no signup.","url":"https://x402-agent-store.rileycraig14.workers.dev/chain/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":["token","owner","spender"],"properties":{"chain":{"type":"string","description":"base|ethereum|optimism|arbitrum|polygon|gnosis (default base)"},"owner":{"type":"string","description":"Token owner wallet (0x...)"},"token":{"type":"string","description":"ERC-20 token contract (0x...)"},"spender":{"type":"string","description":"Approved spender address (0x...)"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"allowance":{"type":"number"},"raw_allowance":{"type":"string"}}}}}}},"responseSchema":{"type":"json","example":{"chain":"base","owner":"0x...","token":"0x...","spender":"0x...","decimals":6,"allowance":1000,"raw_allowance":"1000000000"}},"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_mLfhPy9FytkgcQPBKA5wd","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":"Returns the current ERC-20 token spending allowance approved by an owner address for a specific spender on a given chain","exampleAgentPrompt":"What's the current USDC allowance that my wallet 0xAbC...123 has approved for the Uniswap router 0xDef...456 on Base? Use the token contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48.","exampleUseCases":null,"resultDescription":"A JSON object containing the blockchain network, owner address, token contract address, spender address, token decimals, the human-readable allowance as a number, and the raw allowance as a string in the token's base units (e.g. wei for 18-decimal tokens, micro-units for USDC).","failureModes":["Invalid or non-checksummed address formats return an error","Unsupported chain identifier returns a validation error","Token contract address is not a valid ERC-20 contract — returns error or zero allowance","RPC node unavailability causes timeout or 5xx response","Missing required query parameters (token, owner, spender) return 400 bad request","Payment not included or insufficient — returns 402 Payment Required"],"whenToPreferThis":"Use this endpoint when you need a single, on-demand allowance check for a specific owner/spender/token triple on EVM-compatible chains (Base, Ethereum, Optimism, Arbitrum, Polygon, Gnosis) without needing an API key. Prefer this over ethers.js or web3 direct calls when operating in a serverless or agent context that benefits from HTTP-based on-chain reads with micropayment billing.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T07:05:48.363Z","isFirstParty":false,"canonicalSlug":"erc-20-token-allowance-lookup-1cd1ae5e"}