{"uid":"cap_y7TA0tMiqQXQrxzK83GYr","slug":"nodeflare-transaction-simulation-api-b423cdbc","name":"NodeFlare Transaction Simulation API","description":"Transaction pre-flight: will it revert (and why), gas, and which tokens/ETH move - before you send. Built for agents.","url":"https://rpc.nodeflare.app/data/simulate/x402?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"to":{"type":"string"},"data":{"type":"string"},"from":{"type":"string"},"block":{"type":"string"},"chain":{"type":"string"},"value":{"type":"string"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","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":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_jWxZK_Ex-9Jvv_UwNzeXy","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Simulates an EVM transaction before sending to determine if it will revert, estimate gas, and identify token/ETH balance changes.","exampleAgentPrompt":"Before I submit this swap transaction on Ethereum — from 0xabc...123 calling 0xDef...456 with this calldata — can you simulate it to tell me if it'll revert, how much gas it'll use, and which tokens will move?","exampleUseCases":[{"title":"DeFi swap safety check","prompt":"I'm about to do a Uniswap swap on Ethereum from my wallet 0xabc123, calling the router at 0xdef456 with this calldata. Can you simulate it first to confirm it won't revert, give me a gas estimate, and show me exactly how much ETH and tokens will change hands?"},{"title":"Debug a failing contract call","prompt":"My transaction to this NFT contract keeps failing — the contract is at 0x789abc on Arbitrum and here's the calldata. Can you simulate it and tell me the revert reason so I know what's going wrong?"},{"title":"Token approval and transfer preview","prompt":"Before I sign this transaction to deposit into a yield vault at 0x456def on Base, simulate it for me so I can see the exact token amounts that will leave my wallet and confirm there's no unexpected behavior."}],"resultDescription":"Returns whether the transaction will succeed or revert (with a decoded revert reason if applicable), a gas estimate, and a breakdown of all ERC-20 token transfers and ETH movements that would occur if the transaction were submitted.","failureModes":["Invalid or malformed transaction object returns a 400 error","Unsupported chain ID returns an error indicating the chain is not available","Node timeout or RPC error may return a 503 or gateway error","Insufficient calldata may produce an incomplete simulation result","Contract at target address may not be deployed on specified chain"],"whenToPreferThis":"Choose this endpoint when you need to pre-validate an EVM transaction before signing and broadcasting — especially in agentic workflows where sending a failing transaction would waste gas or cause irreversible state changes. Ideal when you need both the revert prediction AND token flow analysis in a single call, rather than running a separate eth_call plus token event trace. Particularly useful for DeFi interactions, contract debugging, and any agent that must confirm transaction safety before user approval.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-13T00:35:34.710Z","isFirstParty":false,"canonicalSlug":"nodeflare-transaction-simulation-api-b423cdbc"}