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EVM Transaction Simulator (eth_call + eth_estimateGas)
x402
EVM Transaction Simulator (eth_call + eth_estimateGas) is a paid API for AI agents from agent402.tools, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).
Dry-runs a smart contract call or transaction on EVM-compatible networks using eth_call and eth_estimateGas without broadcasting to the blockchain.
Price / call$0.005
Success—
StatusUnknown
How this service works
Dry-run a prospective smart-contract call or transaction without broadcasting it: executes eth_call and eth_estimateGas against the latest block over the same keyless multi-endpoint public RPC pool as /api/evm-rpc (ethereum, base, polygon, arbitrum, optimism). Returns the return data and a gas estimate on success, or {success:false} with the revert reason when the call would fail. Strictly read-only - nothing is signed or broadcast.
Output
Returns the eth_call return data (decoded output bytes from the contract) and the eth_estimateGas value (integer gas units required), giving the agent visibility into whether the transaction would succeed, what it would return, and how much gas it would consume — all without submitting anything to the chain.
Example use cases
Example prompt
“Before I send this transaction, can you simulate calling contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Ethereum with calldata 0x70a08231000000000000000000000000d8dA6BF26964aF9D7eEd9e03E53415D37aA96045 from my address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 and tell me the return value and estimated gas?”
Technical details
Endpoint
POSThttps://agent402.tools/api/tx-simulateWhen to prefer
Use this endpoint when you need to validate or preview a smart contract interaction on any major EVM chain before committing a real transaction. Ideal for agents that need to check for reverts, estimate gas budgets, or inspect return values without risking funds or paying on-chain gas. Prefer this over calling a chain's RPC directly when you want a managed multi-chain pool that already handles endpoint failover across ethereum, base, polygon, arbitrum, and optimism.
Side effects
- Contract reverts: simulation succeeds but returns a revert reason string or custom error bytes
- Invalid address format: 400 error if 'to' is not a valid 0x-prefixed 40-char hex address
- Unsupported network: error if network value is not one of ethereum/base/polygon/arbitrum/optimism
- Invalid calldata: malformed 0x hex in 'data' field causes RPC-level error
- RPC pool timeout: upstream public RPC node unresponsive, returns 5xx
- Payment failure: x402 payment of $0.005 USDC not received, request rejected
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| to | string | 0x-prefixed 40-char target contract/account address. |
| data | string | 0x-prefixed calldata (default 0x - plain value transfer). |
| from | string | Optional sender address (default zero address). |
| value | string | Optional value in wei - decimal string or 0x hex (default 0). |
| network | string | ethereum / base / polygon / arbitrum / optimism (default base). |
Output
Schema · Response
{
"type": "json",
"example": {
"network": "base",
"success": true,
"returnData": "0x00000000000000000000000000000000000000000000000000000000000f4240",
"gasEstimate": 31234,
"revertReason": null
}
}Tags
x402
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