{"uid":"cap_A3pZ6Ond0iPsEToyxG-Rk","slug":"base-mainnet-transaction-gas-preflight-simulator-4bfd4a01","name":"Base Mainnet Transaction Gas Preflight Simulator","description":"Simulate a Base mainnet transaction before submitting it — real eth_estimateGas + eth_call against the given {to, data, value}, returns whether it would succeed, estimated gas, and estimated cost. POST body required. Experimental/informational only — not financial advice.","url":"https://api.nexismvp.com/market/gas-preflight","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"to":{"type":"string","description":"Target address"},"data":{"type":"string","description":"Call data, 0x-prefixed hex (default 0x)"},"chain":{"enum":["base"],"type":"string","description":"Only 'base' supported currently"},"value":{"type":"string","description":"Value in wei, 0x-prefixed hex (default 0x0)"}}},"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_evCsirDevX0TmGTMKSP72","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":"Simulates a Base mainnet transaction before submission using eth_estimateGas and eth_call, returning success/failure prediction, estimated gas units, and estimated cost.","exampleAgentPrompt":"Before I submit this transaction, can you run a preflight simulation on Base mainnet to check if it'll succeed and tell me the estimated gas cost? The to address is 0xAbC123..., the calldata is 0xa9059cbb000..., and I'm sending 0 ETH value.","exampleUseCases":[{"title":"Pre-submit smart contract call check","prompt":"I'm about to call a smart contract on Base — the to address is 0x1234...abcd, the data is 0xa9059cbb0000...00ff, and value is 0. Can you simulate it first and tell me if it'll succeed and what gas I'd need?"},{"title":"DeFi swap gas estimation before execution","prompt":"I want to know if my Uniswap swap on Base will go through before I actually send it — here's the router address 0xDEF...456 and the encoded swap calldata 0x414bf389..., with 0.01 ETH value. Run the preflight and give me the gas estimate."},{"title":"Debugging a potentially reverting transaction","prompt":"My transaction keeps failing on Base and I don't know why — can you preflight-simulate it with to: 0xABC...789, data: 0x5f3759df..., value: 0 and tell me whether it would succeed or revert?"}],"resultDescription":"Returns whether the simulated transaction would succeed or revert on Base mainnet, the estimated gas units required, and the estimated cost in ETH/USD — all derived from a real eth_estimateGas and eth_call against Base mainnet state, without actually broadcasting the transaction.","failureModes":["Invalid or malformed 'to' address returns validation error","Malformed calldata causes eth_call revert with revert reason if available","Missing POST body fields results in 400 error","Base mainnet RPC unavailability causes timeout or 503","Transactions that would revert return success: false with revert reason","Value exceeds simulated sender balance may cause revert in simulation"],"whenToPreferThis":"Choose this endpoint when you need to verify a Base mainnet transaction will succeed and estimate its gas cost before committing to an on-chain submission. Ideal for agents managing smart contract interactions, DeFi operations, or any workflow where a failed transaction would waste gas fees. Prefer this over generic Ethereum gas estimators when working specifically on Base L2.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T03:28:10.701Z","isFirstParty":false}