{"uid":"cap_j9yemb_D_t1r4QYjo1O6a","slug":"erc-20-token-allowance-checker-39a3432f","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/chain/erc20-allowance?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method","bodyType","body"],"properties":{"body":{"type":"object","required":["owner","spender","contract"],"properties":{"owner":{"type":"string"},"network":{"enum":["base","ethereum"],"type":"string","default":"base"},"spender":{"type":"string"},"contract":{"type":"string"}},"additionalProperties":false},"type":{"type":"string","const":"http"},"method":{"enum":["POST"],"type":"string"},"bodyType":{"enum":["json","form-data","text"],"type":"string"}},"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":"registry","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_vQMO2nj_CLe5XypTgS0K6","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":null,"unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Queries the current ERC-20 token allowance granted by an owner address to a spender address on a given blockchain network","exampleAgentPrompt":"Check how much USDC the Uniswap v3 router (0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45) is approved to spend on behalf of my wallet (0xAbCd1234...5678) on the Base network using the USDC contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.","exampleUseCases":[{"title":"DeFi approval audit before swap","prompt":"Before I do a swap, check if the Uniswap router at 0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45 has been approved to spend tokens from my wallet 0xAbCd1234Ef567890 on the USDC contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base."},{"title":"Detect unlimited token approvals","prompt":"Check the token allowance that 0xMaliciousContract has been granted by 0xMyWallet on the DAI contract 0x50c5725949A6F0c72E6C4a641F24049A917DB0Cb on Ethereum — I want to see if I accidentally gave unlimited approval."},{"title":"Smart contract integration verification","prompt":"Verify the ERC-20 allowance the staking contract at 0xStake123 has from the deployer wallet 0xDeploy456 for the reward token at 0xRewardToken789 on Base, so I can confirm the contract can pull funds correctly."}],"resultDescription":"Returns a JSON object indicating the current allowance amount (in token base units) that the spender address is authorized to transfer on behalf of the owner address for the specified ERC-20 contract, along with a status field confirming the query completed successfully.","failureModes":["Invalid Ethereum address format for owner, spender, or contract returns a validation error","Unsupported network value (only 'base' or 'ethereum' are accepted) returns an enum validation error","Non-existent or non-ERC-20 contract address may return zero or an RPC error","Network RPC unavailability causes a timeout or 5xx error","Missing required fields (owner, spender, contract) returns a 400 bad request","Payment not included or insufficient USDC causes x402 payment-required rejection"],"whenToPreferThis":"Use this endpoint when you need a machine-payable, on-demand ERC-20 allowance lookup without managing your own blockchain RPC infrastructure. Prefer this over self-hosted solutions when operating in an agent pipeline that already uses x402 micropayments. Ideal for Base or Ethereum mainnet queries at $0.001 per call, making it cost-effective for occasional or high-frequency checks.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-10T12:37:46.247Z","isFirstParty":false,"canonicalSlug":"erc-20-token-allowance-checker-39a3432f"}