{"uid":"cap_licr9y7azO4prR-1H-DVp","slug":"vextorium-build-evm-transaction-01f9b82f","name":"Vextorium Build EVM Transaction","description":"558 pay-per-call data APIs for AI agents: Solana and EVM on-chain data, tokenized stocks, DeFi, Hyperliquid, economy and official statistics, FX, validation, web and developer tools. Pay in USDC via x402.","url":"https://api.vextorium.com/v1/build-transaction?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"for":{"type":"string"},"since":{"type":"string"},"token":{"type":"string"},"action":{"enum":["native_transfer","token_transfer","approve_token"],"type":"string"},"amount":{"type":"number"},"network":{"type":"string"}}},"responseSchema":{"type":"json","example":{"note":"Unsigned transaction: sign it with your wallet. Vextorium never sees private keys. Check recipient and amount before signing.","token":"USDC","action":"token_transfer","network":"base","decimals":6,"simulation":"ok","transaction":{"to":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","gas":"0x12742","data":"0xa9059cbb0000000000000000000000009b9b3f22bebd1e3e528c2759a2ca34cd2e0184a100000000000000000000000000000000000000000000000000000000000f4240","from":"0xd8dA6BF26964aF9D7eed9e03E53415D37aA96045","type":"0x2","nonce":"0x46","value":"0x0","chainId":"0x2105","maxFeePerGas":"0xa7d8c0","maxPriorityFeePerGas":"0xf4240"},"estimated_gas":62989,"estimated_cost_usd":0.001013,"estimated_native_cost":3.779e-7}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.004","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":"$0.004/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_1obTVD-3lAQ_fhdHituCi","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.004","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Builds an unsigned EVM transaction (native transfer, ERC-20 transfer, or ERC-20 approve) with full fields, gas estimate, EIP-1559 fees, and revert simulation — ready to sign but never submitted.","exampleAgentPrompt":"Build me an unsigned ERC-20 transfer transaction to send 100 USDC from 0xd8dA6BF26964aF9D7eed9e03E53415D37aA96045 to 0x9b9b3f22bebd1e3e528c2759a2ca34cd2e0184a1 on the Base network — I want to see the gas estimate, EIP-1559 fees, and whether it would revert before I sign it.","exampleUseCases":[{"title":"Safe USDC transfer before signing","prompt":"I want to send 50 USDC to 0x9b9b3f22bebd1e3e528c2759a2ca34cd2e0184a1 on Base from my wallet 0xd8dA6BF26964aF9D7eed9e03E53415D37aA96045 — can you build the unsigned transaction and tell me if it'll succeed and what the gas cost will be?"},{"title":"ERC-20 approve for DeFi protocol","prompt":"Prepare an unsigned token_transfer approve transaction for 1000 USDC on Base from 0xd8dA6BF26964aF9D7eed9e03E53415D37aA96045 to the Uniswap router at 0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD — show me the nonce, chainId, and estimated fee in USD before I sign anything."},{"title":"Native ETH transfer transaction prep","prompt":"Build a raw unsigned transaction to send 0.05 ETH from 0xd8dA6BF26964aF9D7eed9e03E53415D37aA96045 to 0xAbCd1234567890abcdef1234567890abcdef1234 on Ethereum mainnet — I need the full transaction object with EIP-1559 fees and a simulation to confirm it won't revert."}],"resultDescription":"Returns a complete unsigned transaction object (to, from, data, value, nonce, chainId, type, maxFeePerGas, maxPriorityFeePerGas, gas), plus the decoded action type, token name, decimals, a simulation status ('ok' or revert warning), estimated gas units, estimated cost in USD, and estimated native token cost. The transaction is ready to be signed by the caller's wallet; private keys are never involved.","failureModes":["Invalid or unsupported network name returns an error","Unrecognized token address or symbol fails lookup","Malformed sender/recipient address causes validation error","Action type not matching token context (e.g. native_transfer with a token address) may error","Simulation result indicates revert — transaction would fail on-chain","Missing required fields (since, action, for, amount) returns schema validation error","Network RPC unavailability causes timeout or error response"],"whenToPreferThis":"Choose this endpoint when an agent needs to construct and inspect a transaction before signing — especially when you want gas estimates, EIP-1559 fee data, and a revert simulation all in one call without any risk of broadcasting. Prefer this over on-chain submission endpoints when the user's wallet signs independently, or when you need to present a cost preview before committing. It supports native transfers, ERC-20 transfers, and ERC-20 approvals across EVM-compatible chains.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-19T12:45:51.917Z","isFirstParty":false,"canonicalSlug":"vextorium-build-evm-transaction-01f9b82f"}