eth_simulateV1

Simulates one or more transaction bundles against the current preconfirmed Flashblock state.

Simulates one or more transaction bundles against the current preconfirmed Flashblock state. Supports state overrides, multi-block simulation, and optional transfer tracing.

This method is only available on Flashblocks-aware endpoints. Connect to https://mainnet-preconf.base.org (or https://sepolia-preconf.base.org) to use it.

Parameters

simulationPayload · object · required

The simulation configuration.

Show Simulation payload fields

blockStateCalls · array · required

Array of block state call objects. Each object represents one simulated block.

Show Block state call fields

calls · array

Array of transaction call objects to simulate within this block.

stateOverrides · object

Per-address state overrides applied before simulation (e.g., balance, nonce, code, storage). Optional.

blockOverrides · object

Block-level overrides (e.g., number, timestamp). Optional.

traceTransfers · boolean

If true, ETH transfer events are included as logs in the result. Optional; defaults to false.

validation · boolean

If true, transaction validation (nonce, balance) is enforced. Optional; defaults to false.

blockParameter · string · required

Use "pending" to simulate against the current Flashblock state.

Returns

result · array

Array of simulated block results, one per entry in blockStateCalls.

Show Block result fields

calls · array

Array of individual call results.

Show Call result fields

status · string

"0x1" for success, "0x0" for failure.

gasUsed · string

Gas used by this call as a hexadecimal integer.

returnData · string

Hex-encoded return data from the call.

logs · array

Logs emitted by this call (including ETH transfer logs if traceTransfers is true).

error · string

Revert reason if the call failed. Optional.

Example

cURL

curl https://sepolia-preconf.base.org \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_simulateV1",
    "params": [
      {
        "blockStateCalls": [
          {
            "calls": [
              { "to": "0x...", "data": "0x..." }
            ],
            "stateOverrides": {}
          }
        ],
        "traceTransfers": true,
        "validation": true
      },
      "pending"
    ],
    "id": 1
  }'