{"service":"Northline ChainKit","summary":"Pay-per-call onchain facts for agents on Base and Arc. x402, USDC on Base, no API key, no signup.","payment":{"protocol":"x402 v2","scheme":"exact","network":"eip155:8453","asset":"USDC","payTo":"0xD4F04c07037c42F84e5B15A7843e58e1C6FccC96"},"endpoints":[{"method":"GET","path":"/v1/address/profile","price":"$0.005","description":"Preflight any address on Base or Arc before paying or approving it: EOA vs contract vs EIP-7702-delegated wallet, EIP-1967 proxy implementation/admin, owner(), Safe multisig threshold, ERC-20 metadata, USDC + native balance, Sourcify verification, and risk flags.","example":{"query":{"chain":"base","address":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"}}},{"method":"GET","path":"/v1/payment/verify","price":"$0.003","description":"Verify that a transaction paid at least N USDC to an address on Base or Arc (handles Arc native-USDC logs). Returns verified true/false, confirmations, matching transfers and reasons. Use it to confirm a customer paid before delivering.","example":{"query":{"chain":"arc","tx":"0x824aaffc374ee2d265e2849f1458364e9227a2d345472f0614753e27fcc307f4","to":"0xf6103b23fd7d528abd3fbcb25935a41fb731e5ba","minAmount":"0.01"}}},{"method":"GET","path":"/v1/tx/explain","price":"$0.004","description":"Explain a Base or Arc transaction in plain JSON: status, confirmations, fee, method selector, created contract, and every ERC-20 transfer decoded with symbol and decimals.","example":{"query":{"chain":"base","tx":"0xaa884cd272aea46834e3a1787c66492d1a2ec4940a9ae11ae5f1dc7c6fefe156"}}},{"method":"GET","path":"/v1/network/status","price":"$0.001","description":"Live block height, gas price and fee estimates (transfer, ERC-20 transfer, contract call) for Base or Arc. On Arc fees are quoted directly in USDC.","example":{"query":{"chain":"arc"}}},{"method":"GET","path":"/v1/usdc/balances","price":"$0.002","description":"USDC and native balance of one address on both Base and Arc in a single call.","example":{"query":{"address":"0xFe5D81D8268CBaC025829CEdD11D5cF6962d4096"}}}],"free":["/","/health","/openapi.json","/llms.txt","/.well-known/x402","/.well-known/x402.json"],"chains":[{"key":"base","chainId":8453},{"key":"arc","chainId":5042}],"related":[{"name":"Northline Unclaimed","url":"https://northline-unclaimed.northline-c86.workers.dev","summary":"Free check for crypto a wallet can still claim (airdrops, rewards, refunds, forgotten DEX balances); full report via x402 at /v1/report.","free":"https://northline-unclaimed.northline-c86.workers.dev/v1/summary?address=","paid":"https://northline-unclaimed.northline-c86.workers.dev/v1/report?address="}]}