{"uid":"cap_RF3WuT5N7Bo2kGUQtF9Jf","slug":"erc-20-token-allowance-checker-201fefe3","name":"ERC-20 Token Allowance Checker","description":"Machine-payable x402 utilities for hashing, Base64, UUID generation, unit and timezone conversion, realtime crypto market data, webpage/document extraction, URL-to-Markdown, metadata, RAG ingestion and deterministic website change detection.","url":"https://x402-gateway-production-1f21.up.railway.app/erc20-allowance?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["owner","spender","contract"],"properties":{"owner":{"type":"string","pattern":"^0x[a-fA-F0-9]{40}$"},"network":{"enum":["base","ethereum"],"type":"string","default":"base"},"spender":{"type":"string","pattern":"^0x[a-fA-F0-9]{40}$"},"contract":{"type":"string","pattern":"^0x[a-fA-F0-9]{40}$"}},"additionalProperties":false}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"status":"ready"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","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":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_eW87c29ucOLJ2Lw-jN9If","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Looks up the current ERC-20 token allowance granted by an owner address to a spender address on a given contract and network.","exampleAgentPrompt":"Check the ERC-20 allowance that owner 0xAbC123...def has granted to spender 0x456...789 on the USDC contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on the Ethereum network.","exampleUseCases":[{"title":"Pre-swap allowance audit","prompt":"Before I execute this swap, check whether my wallet 0xOwnerAddress has already approved the Uniswap router 0xSpenderAddress to spend my USDC at contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Ethereum — I need to know the current allowance."},{"title":"DeFi protocol approval check","prompt":"I'm about to deposit into a yield vault on Base. Can you look up the current token allowance that 0xMyWallet has given to the vault contract 0xVaultAddress for the USDC token at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on base?"},{"title":"Security audit of wallet approvals","prompt":"I want to audit my wallet's token approvals — check how much allowance 0xMyWallet has granted to 0xSuspiciousContract on the DAI contract 0x6B175474E89094C44Da98b954EedeAC495271d0F on Ethereum so I know if I should revoke it."}],"resultDescription":"Returns a JSON object indicating the current ERC-20 allowance (as a token amount) that the owner address has approved for the spender address on the specified contract and network, along with a status field confirming the query succeeded.","failureModes":["Invalid Ethereum address format (not matching 0x + 40 hex chars) returns a 400 error","Unsupported network value (not 'base' or 'ethereum') returns a validation error","Contract address is not a valid ERC-20 contract — may return zero or error","Payment not provided or insufficient USDC — returns HTTP 402 requiring x402 micropayment","RPC or network timeout causes query failure","Zero allowance returned when no approval has been set (valid response, not an error)"],"whenToPreferThis":"Use this endpoint when an AI agent needs to programmatically check ERC-20 token approval state on Base or Ethereum before executing a DeFi transaction, auditing wallet permissions, or determining if an additional approve() call is needed. It is preferable when you need a quick, pay-per-use lookup without managing your own blockchain RPC infrastructure or maintaining a Web3 connection.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-10T12:36:39.505Z","isFirstParty":false,"canonicalSlug":"erc-20-token-allowance-checker-39a3432f"}