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EVM Transaction Simulator
x402
EVM Transaction Simulator is a paid API for AI agents from x402-gateway-production.up.railway.app, paid per call via x402, $0.010000/call, status unknown (last checked 2026-09-15).
Simulate an EVM transaction before sending — returns gas estimates, execution traces, revert reasons, and state diffs
Price / call$0.010000
Success—
StatusUnknown
How this service works
Simulate EVM transactions before sending — get gas estimates, execution traces, and revert reasons
Output
Returns a simulation result including: total gas used, full execution call trace (nested CALL/DELEGATECALL tree with inputs/outputs), emitted logs, nonce and balance diffs, decoded output if ABI available, block number and timestamp of simulation, and any revert reason if the transaction would fail.
Example use cases
Example prompt
“Before I send this transaction, can you simulate it on Ethereum mainnet — it's a call from 0x2222...2222 to 0x1111...1a0 with calldata 0xabcdef and value 0 ETH — tell me the gas estimate, whether it reverts, and the execution trace?”
Technical details
Endpoint
POSThttps://x402-gateway-production.up.railway.app/api/tx/simulateWhen to prefer
Use this endpoint when you need to pre-flight an EVM transaction before submitting it on-chain — especially to catch reverts, estimate gas accurately, or inspect execution traces without spending gas. Prefer this over on-chain submission when testing contract interactions, debugging DeFi calls, or validating calldata correctness. Best for Ethereum mainnet (chainId 1) simulations with full trace detail.
Side effects
- Invalid or missing 'to'/'from' address — 400 bad request
- Unsupported chainId — simulation may fail or return incorrect results
- Malformed calldata hex string — trace returns empty or error
- Insufficient context for revert decoding — revert reason returned as raw hex
- Service unavailable — 5xx from upstream simulation provider
- Payment failure — x402 payment not accepted or insufficient USDC balance
Input
{
"to": "0x1111111254fb6590cd080b51a51f1d88f6d121a0",
"data": "0x",
"from": "0x3333333333333333333333333333333333333333",
"value": "0",
"chainId": 1
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Output
{
"logs": [],
"trace": {
"to": "0x1111111254fb6590cd080b51a51f1d88f6d121a0",
"gas": 9223372036854754000,
"from": "0x3333333333333333333333333333333333333333",
"hash": "0xcf7634532eaf7f0cd0e50d9d261f317884b60be485e5f43c0f78099f07484ff8",
"calls": null,
"input": "0x",
"value": "0",
"output": "0x",
"address": "0x3333333333333333333333333333333333333333",
"gas_used": 0,
"call_type": "CALL",
"caller_op": "CALL",
"caller_pc": 0,
"network_id": "1",
"nonce_diff": [
{
"dirty": "1",
"address": "0x3333333333333333333333333333333333333333",
"original": "0"
}
],
"to_balance": "0",
"function_op": "CALL",
"function_pc": 0,
"block_number": 25326726,
"from_balance": "6875369135801233",
"contract_name": "Unverified",
"intrinsic_gas": 21000,
"decoded_output": null,
"block_timestamp": "2026-06-16T01:15:08Z",
"storage_address": "0x0000000000000000000000000000000000000000",
"absolute_position": 0
},
"gasUsed": 21000,
"success": true
}Tags
x402
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