{"uid":"cap_JCK4l7aR5RbP5MLiWUGke","slug":"base-chain-id-lookup-b471abdd","name":"Base Chain ID Lookup","description":"Base mainnet chain ID (EIP-155) via eth_chainId - confirm which network you're actually talking to.","url":"https://x402.agentindex.world/base/chain-id?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","bodyType","body"],"properties":{"body":{"type":"object","title":"ChainIdInput","properties":{}},"type":{"type":"string","const":"http"},"method":{"enum":["POST","PUT","PATCH"],"type":"string"},"bodyType":{"enum":["json","form-data","text"],"type":"string"}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","title":"ChainIdOutput","required":["chain_id","chain_id_hex","caip2"],"properties":{"caip2":{"type":"string","title":"Caip2"},"chain_id":{"type":"integer","title":"Chain Id"},"chain_id_hex":{"type":"string","title":"Chain Id Hex"}}}}}}},"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_RXfcwNF80Nt_iTlthU9ip","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 Base mainnet chain ID in integer, hex, and CAIP-2 format via eth_chainId, confirming which EVM network you are connected to.","exampleAgentPrompt":"Before I submit this transaction, can you confirm the chain ID of the Base mainnet network — give me the numeric ID, hex value, and the CAIP-2 identifier?","exampleUseCases":[{"title":"Pre-transaction network sanity check","prompt":"Before my agent sends that USDC transfer, double-check that we're actually connected to Base mainnet — what is the chain ID right now?"},{"title":"Wallet config for Base integration","prompt":"I'm setting up a new wallet integration for Base mainnet — what are the chain ID values I need, including the hex format and CAIP-2 identifier?"},{"title":"Multi-chain agent network guard","prompt":"My agent is about to sign a contract interaction — verify we're on Base mainnet and not accidentally on testnet or another chain, and give me the chain ID in all formats."}],"resultDescription":"Returns a JSON object with three fields: chain_id (integer, e.g. 8453), chain_id_hex (hex string, e.g. '0x2105'), and caip2 (CAIP-2 identifier string, e.g. 'eip155:8453') for the Base mainnet network.","failureModes":["RPC connectivity issues may return a 5xx error if the Base node is unreachable","Malformed request body may return a 400 validation error","Payment failure (x402) may block the call if USDC balance is insufficient"],"whenToPreferThis":"Use this endpoint when an AI agent or automated system needs to programmatically confirm it is connected to Base mainnet before executing transactions, signing messages, or configuring wallets — especially in multi-chain environments where network confusion could cause fund loss. Prefer this over manual RPC calls when you need all three chain ID formats (integer, hex, CAIP-2) in one response.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-10T12:40:44.530Z","isFirstParty":false,"canonicalSlug":"base-chain-id-lookup-b471abdd"}