{"uid":"cap_yeYV0Giu28MsgbE516ytI","slug":"eip-155-chain-id-lookup-via-unykorn-node-0cebe482","name":"EIP-155 Chain ID Lookup via UnyKorn Node","description":"EIP-155 chain id, confirmed from the node itself — Genesis402 / UnyKorn Operator Network","url":"https://twin.unykorn.org/evm-chain-id?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"params":{"type":"object","properties":{"chain":{"enum":["ethereum","base","polygon","arbitrum","optimism","bsc","avalanche","gnosis","linea","scroll"],"type":"string"}}}}},"responseSchema":{"type":"json","example":{"ok":true,"type":"evm-chain-id","receipt":{"tx_hash":"0x<64hex>","amount_usd":0.001,"receipt_id":"g402-<16hex>"},"generated_at":"<iso8601>"}},"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_071EDJRR0dErszubcLb1y","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 EIP-155 chain ID for a specified EVM-compatible network, confirmed directly from the node itself.","exampleAgentPrompt":"What is the EIP-155 chain ID for Base, confirmed directly from the node?","exampleUseCases":[{"title":"Verify chain ID before signing","prompt":"Before I sign this transaction, can you confirm the official EIP-155 chain ID for Polygon directly from the node so I know I'm on the right network?"},{"title":"Cross-chain routing validation","prompt":"I'm setting up a cross-chain bridge and need the node-confirmed chain ID for Arbitrum — can you look that up for me?"},{"title":"Developer network configuration","prompt":"I'm configuring my dApp to support Optimism and need the correct EIP-155 chain ID confirmed from a live node — what is it?"}],"resultDescription":"Returns a JSON object with ok status, the type field set to 'evm-chain-id', the chain ID value confirmed from the live node, a payment receipt containing tx_hash, amount_usd, and receipt_id, and a generated_at ISO8601 timestamp.","failureModes":["Unsupported chain name returns validation error — only the ten enumerated chains are accepted","Node connectivity issues may cause timeout or 5xx error","Invalid or missing 'chain' parameter results in schema validation failure","Payment failure via x402 protocol may prevent execution"],"whenToPreferThis":"Prefer this endpoint when you need a node-authoritative confirmation of an EVM chain ID rather than a hardcoded constant — useful for security-sensitive signing workflows, cross-chain routing validation, or when you want a receipted, auditable chain ID lookup across the ten most popular EVM networks (Ethereum, Base, Polygon, Arbitrum, Optimism, BSC, Avalanche, Gnosis, Linea, Scroll).","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-01T18:55:19.848Z","isFirstParty":false,"canonicalSlug":"eip-155-chain-id-lookup-via-unykorn-node-0cebe482"}