{"uid":"cap_ubRJHQoGeu7oU5Q9dfPWf","slug":"base-transaction-simulator-4a597722","name":"Base Transaction Simulator","description":"Pay-per-call crypto microdata for trading/onchain AI agents via x402 (USDC on Base): Base gas, token risk, balances, multi-venue prices, Hyperliquid book/funding, kimchi premium. No API keys.","url":"https://kr-x402-mvp.kgy5612.workers.dev/crypto/tx-simulate?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","properties":{"to":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","examples":["0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"],"description":"Target contract or recipient"},"data":{"type":"string","pattern":"^0x([0-9a-fA-F]{2})*$","description":"Calldata (default 0x)"},"from":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","examples":["0xe4be4d0bd82d8e68203deff81f79ede0529f2617"],"description":"Sender (signer) address"},"calls":{"type":"string","description":"URL-encoded JSON array of up to 5 {to,data,value_eth|value} run in order from the same sender"},"value_eth":{"type":"string","examples":["0.01"],"description":"ETH to send, decimal (default 0)"}},"additionalProperties":false}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"from":"0xe4be4d0bd82d8e68203deff81f79ede0529f2617","next":["/crypto/base-gas","/crypto/tx-status?hash="],"block":53272234,"calls":[{"to":"0x833589fcd6edb6e08f4c7c32d4f71b54bda02913","index":0,"success":true,"function":"transfer(address,uint256)","gas_used":45047,"revert_reason":null}],"chain":"base","flags":[],"fee_eth":5e-7,"fee_usd":0.0019,"success":true,"summary":"1 call succeeds; sender sends 0.001 USDC","verdict":"SAFE_TO_SEND","approvals":[],"transfers":[{"to":"0xa587d73489f8f09d1975f1ddbb1c61c93e8fa9d7","from":"0xe4be4d0bd82d8e68203deff81f79ede0529f2617","token":"0x833589fcd6edb6e08f4c7c32d4f71b54bda02913","amount":0.001,"symbol":"USDC"}],"gas_used_total":45047,"sender_changes":{"USDC":-0.001},"balance_changes":{"0xa587d73489f8f09d1975f1ddbb1c61c93e8fa9d7":{"USDC":0.001},"0xe4be4d0bd82d8e68203deff81f79ede0529f2617":{"USDC":-0.001}}}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.003","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":"$0.003/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_u-5_yfXvYgBjavBgh2L9i","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.003","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Simulates one or more Base blockchain transactions to predict gas usage, token transfers, balance changes, and safety verdict before broadcasting","exampleAgentPrompt":"Before I sign this USDC transfer on Base — from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 to contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 with calldata 0xa9059cbb... — simulate it and tell me if it's safe, what tokens move, and what the gas fee will be.","exampleUseCases":[{"title":"Pre-flight safety check for DeFi trade","prompt":"I'm about to call a DEX router on Base to swap 100 USDC for ETH — sender is 0xe4be4d0bd82d8e68203deff81f79ede0529f2617, contract is 0x6131B5fae19EA4f9D964eAc0408E4408b66337b5, with the encoded swap calldata. Simulate it first and tell me the verdict, what tokens leave my wallet, and the estimated fee."},{"title":"Batch multi-call simulation","prompt":"I need to simulate three chained calls on Base in sequence from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — approve USDC, deposit into a vault, then claim rewards. Can you dry-run all three together and show me which ones succeed, how much gas each uses, and the net balance changes?"},{"title":"Rug / unexpected approval detection","prompt":"Someone sent me a transaction to sign on Base — to address 0xDeAdBeEf... with some calldata. Before I sign anything, simulate it from my address 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 and check whether it tries to drain my tokens or set any unexpected approvals."}],"resultDescription":"Returns a JSON object with: overall success flag and safety verdict (SAFE_TO_SEND or warning), per-call breakdown (function decoded, gas used, revert reason if any), total gas used and fee in both ETH and USD, list of token transfers with amounts and symbols, net balance changes per address, any ERC-20 approval events detected, current block number, and suggested next sibling endpoints to call.","failureModes":["Invalid address format returns 400 validation error","Malformed calldata hex returns parse error","Simulation reverts — revert_reason populated and success=false","Network congestion may cause delayed simulation response","Unparseable function selector returns raw calldata without decoded function name","Payment failure via x402 if insufficient USDC balance returns 402"],"whenToPreferThis":"Use this endpoint when an AI agent needs to preview exactly what a Base L2 transaction will do — token flows, gas cost, safety — before committing. Prefer it over static gas estimators when you need decoded transfers, balance deltas, and a safety verdict in one call. Also prefer it for batch simulation of up to 5 chained calls in a single request. It requires no API key (pay-per-call via x402 USDC micropayment) making it ideal for autonomous agent workflows.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-31T18:41:10.412Z","isFirstParty":false,"canonicalSlug":"base-transaction-simulator-4a597722"}