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x402engine EVM Transaction Simulator
x402
x402engine EVM Transaction Simulator is a paid API for AI agents from x402engine.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-16).
Simulates an EVM transaction before broadcast, returning gas estimates, execution traces, and revert reasons
Price / call$0.01
Success—
StatusUnknown
How this service works
x402engine — Simulate EVM transactions before sending — get gas estimates, execution traces, and revert reasons
Output
Returns a simulation result including predicted gas usage, full execution trace of EVM opcodes and calls, and if applicable a decoded revert reason explaining why the transaction would fail — all without submitting anything to the blockchain.
Example use cases
Debug a reverting DeFi transaction
“My swap transaction keeps failing — can you simulate it on Ethereum mainnet from 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 to the Uniswap router at 0xE592427A0AEce92De3Edee1F18E0157C05861564 with this calldata and tell me the exact revert reason?”
Estimate gas before a contract deployment
“Before I deploy this contract, simulate the transaction on Base (network ID 8453) from 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 to 0x0000000000000000000000000000000000000000 with my bytecode as calldata and give me an accurate gas estimate.”
Validate a token approval call
“Can you dry-run an ERC-20 approve call for me on Optimism (network ID 10) — from 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 to the USDC contract, with the approval calldata, and confirm it won't revert before I actually send it?”
Technical details
Endpoint
POSThttps://x402engine.app/api/tx/simulate?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to pre-flight an EVM transaction on any supported chain (mainnet, Base, Optimism, etc.) before actually broadcasting it — ideal for catching reverts, estimating gas accurately, or debugging calldata without spending real gas or risking failed on-chain transactions. Prefer this over node-level eth_call when you also want structured execution traces and decoded revert reasons in a single pay-per-call API without managing RPC infrastructure.
Side effects
- Invalid or malformed address returns a validation error
- Unsupported network_id returns an error indicating the chain is not available
- Malformed calldata hex string causes a simulation failure
- Insufficient gas limit causes the simulation to revert with out-of-gas
- Contract state at simulation time may differ from broadcast time, leading to stale results
- Payment failure ($0.01 USDC not provided) results in HTTP 402 rejection
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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