{"uid":"cap_BSwScYAmvpgH-JZZrjPL8","slug":"quartermaster-eth-erc-20-balance-checker-on-base-4eb3a932","name":"Quartermaster ETH/ERC-20 Balance Checker on Base","description":"Check ETH and USDC (or any ERC-20) balance of an address on Base — pre-flight funding checks for payments and settlement.","url":"https://quartermaster.surewhynot.app/v1/balance","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["address"],"properties":{"token":{"type":"string","default":"usdc","description":"'usdc' or an ERC-20 contract address"},"address":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","description":"EVM address to check on Base"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"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_YZ7WBqLj4p8mdVp45wHJB","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":"Returns the ETH or ERC-20 (e.g. USDC) token balance of a given wallet address on the Base blockchain for pre-flight funding checks.","exampleAgentPrompt":"Before sending the payment, check whether wallet 0xAbC1234567890abcdef1234567890abcdef123456 has enough USDC on Base to cover it — look up its USDC balance for me.","exampleUseCases":null,"resultDescription":"Returns the token balance (as a numeric amount) for the queried EVM address on Base, for either ETH, USDC (default), or any specified ERC-20 contract address.","failureModes":["Invalid or malformed EVM address (not matching 0x + 40 hex chars) returns a validation error","Unknown or invalid ERC-20 contract address returns an error or zero balance","Network issues reaching Base RPC return a connectivity error","Rate limiting or payment failure (x402) if the $0.001 USDC fee is not satisfied"],"whenToPreferThis":"Use this endpoint when you need to verify a wallet's on-chain token balance on Base before executing or approving a payment, particularly in x402 payment workflows. Prefer this over generic block explorers when you need a programmatic, agent-callable balance check with minimal latency.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T12:47:29.453Z","isFirstParty":false}