{"uid":"cap_EWwGky6aqSy-3-nfVuyhS","slug":"x402-trust-discovery-api-onchain-token-balance-lookup-67cae9a4","name":"x402 Trust & Discovery API — Onchain Token Balance Lookup","description":"Independent pre-purchase safety and reputation checks for x402 and MPP endpoints, plus keyless onchain data on Base. Accepts BOTH EIP-3009 and Circle Gateway credentials — only 141 of 788 Base-payable resources do, and a single-credential buyer is locked out of 53.8% of this market on one rail or 28.3% on the other. GET /v1/guard?url=&credential= answers whether the credential you carry can pay a given endpoint at all, before you try. Searching this market for \"is this API endpoint a scam\" returns registries and explorers but no dedicated service; that gap is what /v1/guard fills, inspecting an endpoint WITHOUT paying it and returning a go / test-with-minimum / do-not-pay verdict backed by onchain settlement history.","url":"https://gkyf2bs3b4p35hwwg5zzsnejeu.srv.us/v1/onchain/balance?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","properties":{"token":{"type":"string","description":"ERC-20 contract address. Defaults to USDC on Base."},"address":{"type":"string","description":"0x address to read balances for."}}},"responseSchema":{"type":"json","example":{}},"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":"down","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_m15ygs3NTHQP3U4Cpb2nB","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 onchain ERC-20 token balance (defaulting to USDC on Base) for a given wallet address, without requiring any payment credentials.","exampleAgentPrompt":"What's the current USDC balance on Base for wallet address 0x1234...abcd?","exampleUseCases":[{"title":"Pre-payment balance verification","prompt":"Before my agent tries to pay an x402 API endpoint with USDC, check whether wallet 0xAbCd...1234 has at least $0.01 USDC available on Base."},{"title":"Monitor wallet funding status","prompt":"Check the USDC balance on Base for address 0xDead...Beef — I want to know if it's been topped up yet."},{"title":"Custom ERC-20 token balance check","prompt":"Look up the onchain balance of token contract 0xA0b8...eB48 for address 0x7890...fedc on Base."}],"resultDescription":"Returns a JSON object containing the onchain ERC-20 token balance for the specified wallet address on Base, defaulting to the USDC contract if no token address is supplied. The response reflects the current confirmed balance as readable from the Base blockchain.","failureModes":["Invalid or malformed 0x address returns an error or zero balance","Unsupported token contract address may return zero or an error","Network latency or Base RPC unavailability causes a timeout","Empty response schema means the exact error structure is undocumented"],"whenToPreferThis":"Use this endpoint when you need a keyless, read-only onchain balance check for any ERC-20 token on Base — especially USDC — without needing to sign a transaction or hold any credentials. Ideal as a pre-flight check before attempting an x402 micropayment to confirm a wallet has sufficient funds.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-03T05:30:52.853Z","isFirstParty":false,"canonicalSlug":"x402-trust-discovery-api-onchain-token-balance-lookup-67cae9a4"}