{"uid":"cap_Q4erT1CI-Beypkujuef0o","slug":"evm-transaction-simulation-eth-call-pre-flight-87379691","name":"EVM Transaction Simulation (eth_call Pre-flight)","description":"Pay-per-call on-chain API for AI agents and developers: wallet audits, token safety audits (honeypot detection), live gas prices, token prices, transaction receipts, balances, ENS resolution, block data, ERC-20 allowances, transaction simulation, swap quotes and multicall batches — all computed on-chain via public RPCs (no external market API). Pay per request in USDC on Base via the x402 exact scheme (EIP-3009 transferWithAuthorization). No API key, no signup, no subscription.","url":"https://x402-audit.tatschluizguilherme.workers.dev/simulate","method":"GET","headers":{},"bodySchema":null,"responseSchema":{"type":"json","example":{"to":"0x833589fcd6edb6e08f4c7c32d4f71b54bda02913","from":"0x8e8d53a67b59e6f2a28e0d6d52012a2b0e3e1886","network":"base","success":true,"returnData":"0x0000000000000000000000000000000000000000000000000000000000000000","blockNumber":24400123,"gasEstimate":30248,"requestedAt":"2026-08-05T01:30:00.000Z"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.1","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"registry","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":"$0.1/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.1","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.1","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_qAI-aDQ_g3MPcIVFKulPg","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.1","costPer":"request","priority":0,"asset":null,"unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Simulates an EVM transaction via eth_call on Base, Optimism, or Ethereum Mainnet before submission, returning success/failure, return data, decoded revert reason, and gas estimate","exampleAgentPrompt":"Before I submit this transaction, simulate it on Base: from 0xAbC...123, to contract 0xDeF...456, with this calldata 0xa9059cbb000...0001, value 0 ETH — will it succeed, and what's the gas estimate?","exampleUseCases":[{"title":"Pre-flight DeFi swap safety check","prompt":"Before I execute this swap on Base, can you simulate it for me? From wallet 0x1234...abcd, to the Uniswap router 0x2626...6868, with calldata 0x...swapExactTokensForTokens, value 0 ETH — I want to know if it'll revert and roughly how much gas it'll use."},{"title":"Debug a reverting contract call","prompt":"My contract interaction keeps failing on Optimism and I need to know why. Simulate this call from 0xOwner...1111 to contract 0xNFT...2222 with calldata 0x23b872dd...transferFrom, value 0 — can you tell me the decoded revert reason?"},{"title":"Gas estimation for Ethereum mainnet interaction","prompt":"I'm about to call a staking contract on Ethereum mainnet and need a gas estimate before I commit. Simulate the call from 0xMy...wallet to 0xStaking...contract with this calldata 0xa694fc3a...0de0b6b3, value 0.5 ETH — does it succeed and what's the gas?"}],"resultDescription":"Returns a success boolean indicating whether the simulated call would succeed, the raw return data from the call, a decoded human-readable revert reason (if the call reverts with Error(string)), and a gas estimate for the transaction — all derived directly from an on-chain eth_call without using any block explorer API.","failureModes":["Invalid or malformed calldata causes simulation error","Unsupported chain specified returns an error","Missing required fields (from/to/data) returns a bad request error","RPC node timeout or connectivity issue results in a service error","Value field mismatch with contract requirements causes unexpected revert in simulation","Custom revert reasons beyond Error(string) (e.g. custom errors) may not be fully decoded"],"whenToPreferThis":"Choose this endpoint when you need to pre-flight an EVM transaction to check for reverts, decode revert reasons, or estimate gas on Base, Optimism, or Ethereum Mainnet without submitting on-chain. Prefer this over block explorer APIs (Etherscan, etc.) since it performs a live eth_call directly against the node, giving real-time simulation results. Ideal for DeFi agents, smart contract debuggers, or any workflow that must validate transaction safety before committing gas.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-16T00:44:11.244Z","isFirstParty":false}