{"uid":"cap_cWQcGt_YnBSjTZkvYEPqQ","slug":"alchemy-transaction-simulator-x402-bed863e9","name":"Alchemy Transaction Simulator (x402)","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/api/alchemy/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_38CZHMGy34AHx809uK1LA","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 EVM transactions on Base, returning gas cost, token transfers, balance changes, approval events, and a SAFE/UNSAFE verdict — before broadcasting on-chain.","exampleAgentPrompt":"Before I send this USDC transfer on Base — simulate the call from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 to 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 with calldata 0xa9059cbb... and tell me if it's safe, how much gas it uses, and what token balance changes I should expect.","exampleUseCases":[{"title":"Safe-send check before USDC transfer","prompt":"I'm about to send 50 USDC on Base from my wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 to 0xa587d73489f8f09d1975f1ddbb1c61c93e8fa9d7 — can you simulate the transaction and tell me if it will succeed, what the gas fee will be in USD, and whether any unexpected approvals are granted?"},{"title":"DeFi contract call dry-run","prompt":"Dry-run this swap calldata on Base for me: sender is 0xe4be4d0bd82d8e68203deff81f79ede0529f2617, target is 0x2626664c2603336E57B271c5C0b26F421741e481, data is 0x414bf389... — give me the verdict, gas used, and every token that changes hands."},{"title":"Batch transaction preview for agent workflow","prompt":"I have 3 contract calls I want to run in sequence on Base from address 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — simulate them all as a batch and tell me if the whole sequence succeeds, what the total gas cost is, and if any call reverts."}],"resultDescription":"Returns a JSON object with: overall success boolean, a human-readable summary and SAFE_TO_SEND/UNSAFE verdict, per-call breakdown (function name, gas used, revert reason if any), a list of token transfers (from/to/amount/symbol), net balance changes per address, approval events detected, total gas used, fee in ETH and USD, current block number, and suggested next API endpoints.","failureModes":["Invalid Ethereum address format returns 400 validation error","Malformed calldata (non-hex) rejected by schema validation","Simulation reverts if sender lacks sufficient balance for the call","More than 5 calls in a batch returns an error","x402 payment failure blocks the call if USDC micropayment is not processed","Network congestion or Alchemy downtime may cause timeout","Unsupported chain (non-Base) not handled by this endpoint"],"whenToPreferThis":"Use this endpoint when an AI agent needs to verify that a Base transaction is safe before broadcasting — especially when token approvals, unexpected transfers, or revert risk are concerns. Prefer over generic gas estimators because it returns a full semantic breakdown: transfer list, balance delta, approval events, and a plain-English verdict. Ideal for onchain agents that need no API key and pay per call via x402 USDC micropayments on Base.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-11-02T18:33:06.724Z","isFirstParty":false,"canonicalSlug":"alchemy-transaction-simulator-x402-bed863e9"}