Documentation Index
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The simulate endpoint executes your transaction on a forked EVM state and returns predicted output amounts, gas consumed, and a simulationId for subsequent validation.
POST https://quoter.api.enso.build/api/v1/simulate
tokenIn, tokenOut, and amountIn), use the batch endpoint:
POST https://quoter.api.enso.build/api/v1/simulate/batch
transactions (an array of TransactionDto) instead of transaction. The response contains a results array in the same order — each item has the same shape as a single /simulate response, with its own simulationId for /validate. Up to 50 transactions per request.
curl -X POST https://quoter.api.enso.build/api/v1/simulate/batch \
-H "Authorization: Bearer $ENSO_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"chainId": 1,
"transactions": [
{
"data": "0x3593564c...",
"value": "1000000000000000000",
"to": "0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD",
"from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
},
{
"data": "0x472b43f3...",
"value": "1000000000000000000",
"to": "0xDef1C0ded9bec7F1a1670819833240f027b25FDF",
"from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
}
],
"tokenIn": ["0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE"],
"tokenOut": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
"amountIn": ["1000000000000000000"]
}'
Request Parameters
Top-level fields
| Field | Type | Required | Description |
|---|
chainId | number | Yes | Chain ID (e.g., 1 for Ethereum, 42161 for Arbitrum) |
transaction | TransactionDto | Yes | The transaction to simulate (see below) |
tokenIn | string[] | Yes | Input token addresses |
tokenOut | string[] | Yes | Output token addresses to track |
amountIn | string[] | Yes | Input amounts in wei (one per tokenIn) |
preSimulationTransactions | TransactionDto[] | No | Setup transactions to run before the main simulation |
Transaction fields
| Field | Type | Required | Description |
|---|
data | string | Yes | Hex-encoded calldata |
value | string | Yes | Native token value in wei |
to | string | Yes | Target contract address |
from | string | Yes | Sender address |
operationType | number | No | 0 = Call (default), 1 = DelegateCall |
receiver | string | No | Token receiver address (if different from sender) |
spender | string | No | Spender address for token approvals |
executor | string | No | Contract executor address |
origin | string | No | Original caller address |
authorityDelegate | string | No | Delegation authority address |
initCode | string | No | Init code for contract creation |
Response
| Field | Type | Description |
|---|
simulationId | string | UUID for this simulation. Use with /validate. |
chainId | number | Chain ID the simulation ran on |
result.status | "Success" | "Error" | Whether the simulated transaction would succeed |
result.amountOut | string[] | Predicted output amounts in wei (one per tokenOut) |
result.gas | string | Gas consumed during simulation |
result.error | object | Error details when status is "Error" |
Examples
Token Swap
Vault Deposit
DelegateCall
Simulate a swap from ETH to USDC on Ethereum mainnet.curl -X POST https://quoter.api.enso.build/api/v1/simulate \
-H "Authorization: Bearer $ENSO_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"chainId": 1,
"transaction": {
"data": "0x3593564c...",
"value": "1000000000000000000",
"to": "0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD",
"from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
},
"tokenIn": ["0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE"],
"tokenOut": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
"amountIn": ["1000000000000000000"]
}'
Simulate depositing USDC into a Yearn vault.curl -X POST https://quoter.api.enso.build/api/v1/simulate \
-H "Authorization: Bearer $ENSO_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"chainId": 1,
"transaction": {
"data": "0x6e553f65...",
"value": "0",
"to": "0xa354F35829Ae975e850e23e9615b11Da1B3dC4DE",
"from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
},
"tokenIn": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
"tokenOut": ["0xa354F35829Ae975e850e23e9615b11Da1B3dC4DE"],
"amountIn": ["1000000000"]
}'
Simulate with operationType: 1 for smart account (DelegateCall) execution.curl -X POST https://quoter.api.enso.build/api/v1/simulate \
-H "Authorization: Bearer $ENSO_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"chainId": 1,
"transaction": {
"data": "0x3593564c...",
"value": "0",
"to": "0x80EbA3855878739F4710233A8a19d89Bdd2ffB8E",
"from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
"operationType": 1
},
"tokenIn": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
"tokenOut": ["0xdAC17F958D2ee523a2206206994597C13D831ec7"],
"amountIn": ["1000000000"]
}'
Handling Simulation Errors
When result.status is "Error", the result.error field contains details about why the transaction would fail. Common causes:
- Contract revert — The transaction would revert on-chain (e.g., insufficient balance, failed require check)
- Invalid calldata — The
data field doesn’t match any function signature on the target contract
- Out of gas — The transaction requires more gas than available
const simulation = await fetch("https://quoter.api.enso.build/api/v1/simulate", {
method: "POST",
headers: { "Authorization": `Bearer ${ENSO_API_KEY}`, "Content-Type": "application/json" },
body: JSON.stringify(request),
}).then((res) => res.json());
if (simulation.result.status === "Error") {
console.error("Simulation failed:", simulation.result.error);
} else {
console.log("Predicted output:", simulation.result.amountOut);
console.log("Gas estimate:", simulation.result.gas);
}
