{"uid":"cap_FQELs56902Daq6QDXBaNU","slug":"coin-railz-transaction-builder-9537f688","name":"Coin Railz Transaction Builder","description":"Pre-validated transaction encoding for agent-to-agent transfers (B2B2C infrastructure)","url":"https://coinrailz.com/x402/transaction-builder","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"query":{"type":"string","description":"Query parameter for the service"}}},"responseSchema":{"type":"application/json","format":"json","example":{"result":"Service executed successfully","service":"transaction-builder","success":true,"timestamp":"2026-02-07T01:42:05.861Z"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.3","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"settled","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":"$0.3/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.3","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.3","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Od5Z6417bMbCAwl5h-181","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.3","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Encodes and pre-validates crypto transfer transactions for agent-to-agent (B2B2C) payment flows before submission to the blockchain","exampleAgentPrompt":"Build me a pre-validated transaction payload to transfer 50 USDC from my agent wallet 0xABC...123 to recipient 0xDEF...456 on Base mainnet so I can sign and broadcast it.","exampleUseCases":[{"title":"Autonomous agent-to-agent payment settlement","prompt":"Set up a pre-validated transaction so my service agent can automatically pay vendor agents 0.5 ETH each time they complete a task, all ready to sign and broadcast to Ethereum mainnet."},{"title":"DeFi bot token swap preparation","prompt":"Build me an encoded transaction payload to swap 100 USDC for DAI on Uniswap before my trading bot signs it, I want the validated payload back first."},{"title":"Batch crypto payroll for agent fleet","prompt":"Generate pre-validated transaction objects to distribute weekly USDC payments to my 10 deployed agents across different wallets on Polygon, so they can each sign and settle autonomously."}],"resultDescription":"Returns a JSON object containing the encoded transaction payload ready for signing, a success flag, the service name ('transaction-builder'), and a timestamp. The agent receives a structured transaction object it can directly sign and submit to the target blockchain network.","failureModes":["Invalid sender or recipient address format returns validation error","Unsupported chain ID results in error response","Missing required fields (amount, token, addresses) causes 400-level error","Insufficient USDC balance to pay the $0.30 per-call fee blocks the request","Malformed token contract address triggers encoding failure"],"whenToPreferThis":"Choose this endpoint when your agent needs to programmatically construct and pre-validate a blockchain transaction before signing — especially for autonomous agent-to-agent (B2B2C) payment pipelines where pre-validation reduces broadcast failures. Prefer this over raw RPC calls when you want a structured, validated transaction object returned as JSON without handling raw ABI encoding yourself.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T06:43:35.959Z","isFirstParty":false}