{"uid":"cap_a16m003xUF6Ju1SfYyYX0","slug":"mach-gallery-base-erc-20-allowance-lookup-cadacf81","name":"Mach Gallery Base ERC-20 Allowance Lookup","description":"Fast, low-cost Base data for autonomous agents. No API keys, no subscriptions; pay per call with USDC over x402.","url":"https://api.mach.gallery/api/base/allowance?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"owner":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","description":"ERC-20 token owner address on Base mainnet."},"token":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","description":"ERC-20 or token contract address on Base mainnet."},"spender":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","description":"ERC-20 spender address whose allowance is being checked."}}},"responseSchema":{"type":"json","example":{"network":"eip155:8453","allowance_atomic":"0"}},"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_w7-0aCEBnzH6wAlUaJcwu","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 ERC-20 token allowance granted by an owner to a spender on the Base network","exampleAgentPrompt":"Check the USDC allowance that my wallet 0xAbC1234567890abcdef1234567890ABCDEF12345 has approved for the Uniswap router 0xDef9876543210DEFabc9876543210DEFabc98765 on Base — what's the current token approval amount?","exampleUseCases":[{"title":"Pre-swap approval check for DeFi agent","prompt":"Before I try to swap tokens on Base, check whether my wallet 0xAbC1234567890abcdef1234567890ABCDEF12345 has approved enough USDC (0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) for the Uniswap router 0xDef9876543210DEFabc9876543210DEFabc98765 to spend."},{"title":"Monitor stale token approvals","prompt":"Tell me the current allowance that 0xOwner123456789012345678901234567890123456 has given to 0xSpender789012345678901234567890123456789 for the token at 0xToken456789012345678901234567890123456789 on Base — I want to know if it's still set to an unlimited amount."},{"title":"Verify protocol permission before yield deposit","prompt":"I'm about to deposit into a yield vault on Base — can you check how many tokens the vault contract 0xVault123456789012345678901234567890123456 is currently allowed to pull from my address 0xMyWallet78901234567890123456789012345678 for the WETH token 0x4200000000000000000000000000000000000006?"}],"resultDescription":"Returns a JSON object containing the network identifier (e.g. 'eip155:8453' for Base mainnet) and the allowance amount in atomic units (smallest denomination) as a string, representing how many tokens the spender is authorized to transfer on behalf of the owner.","failureModes":["Invalid EVM address format for owner, token, or spender returns a validation error","Token address does not correspond to a deployed ERC-20 contract on Base, resulting in an error or zero allowance","Network congestion or RPC node issues may cause timeouts","Payment failure via x402 if insufficient USDC balance prevents the $0.003 call fee"],"whenToPreferThis":"Choose this endpoint when you need a fast, pay-per-call allowance check on the Base network without managing API keys or subscriptions. It is ideal for autonomous agents that need on-demand ERC-20 approval data at low cost ($0.003/call) and can pay via USDC over x402. Prefer it over building your own RPC calls when simplicity and cost predictability matter.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T04:37:22.531Z","isFirstParty":false,"canonicalSlug":"mach-gallery-base-erc-20-allowance-lookup-cadacf81"}