Simulation

Simulation

eth_call and eth_estimateGas are trusted-mode simulation methods.

• trusted mode: supported
• light mode: unsupported (-32010)

Both methods execute on a checkpoint-and-revert path and do not mutate canonical state.

Methods

Method	Exact params	Exact result	Errors
eth_call	[tx, block] or [tx, block, stateOverrides]	HexData	-32602 malformed tx, selector, or overrides; -32603 runtime execution failure; -32010 in light mode
eth_estimateGas	[tx], [tx, block], or [tx, block, stateOverrides]	QuantityHex	-32602 malformed tx, selector, or overrides; -32603 runtime execution failure; -32010 in light mode

Any tuple length not listed above returns -32602.

Execution outcome semantics:

• success path:
  • eth_call returns HexData
  • eth_estimateGas returns QuantityHex
• runtime execution failure path (for example revert, out-of-gas, invalid execution in simulation context): JSON-RPC -32603 with message Internal error, no result, and no revert-data result payload
• omitted transaction field defaults:
  • from: trusted runtime coinbase
  • gas: selected simulation block gas limit
  • gasPrice: trusted runtime gas price
  • value: 0x0
  • nonce: no nonce check
  • data/input: empty bytes
• create semantics:
  • omitted to or to: null executes the request as contract creation
  • create simulations use the sender’s current nonce for CREATE address and collision semantics
  • created code and the temporary sender nonce increment are reverted before the response
• gas estimation:
  • computes intrinsic gas for the runtime-owned active hardfork and whether the request is create or call
  • uses the explicit gas value as the upper bound when present; otherwise uses the selected simulation block gas limit
  • rejects upper bounds below intrinsic gas or above the selected block gas limit with -32603
  • requires the upper bound to execute successfully, then binary-searches for the lowest successful gas limit in [intrinsic, upperBound]
• block environment:
  • current-head simulations use the trusted runtime chain ID, coinbase, head block number, head timestamp, gas limit, base fee, blob base fee, and active one-shot block-environment overrides
  • state-backed simulation is current-head only; selectors that resolve to a non-head block return -32602
  • omitted gas defaults to the selected simulation block gas limit

TransactionRequest

Allowed fields only:

Field	Type	Rule
from	Address	optional for eth_call and eth_estimateGas
to	Address or null	omitted or null for create
gas	QuantityHex	optional
gasPrice	QuantityHex	optional
value	QuantityHex	optional
nonce	QuantityHex	optional
data	HexData	optional
input	HexData	optional alias of data

Rules:

• data and input may both be omitted
• if both are present, they must be byte-identical
• any field not listed above returns -32602
• unsupported request fields return -32602: maxFeePerGas, maxPriorityFeePerGas, maxFeePerBlobGas, blobVersionedHashes, accessList, authorizationList, type, chainId

StateOverrideSet

stateOverrides is an object keyed by address. Each value may include:

Field	Type
balance	QuantityHex
nonce	QuantityHex
code	HexData
storage	object mapping Bytes32 slot -> Bytes32 value

Example:

{
  "0x0000000000000000000000000000000000000001": {
    "balance": "0xde0b6b3a7640000",
    "nonce": "0x1",
    "code": "0x60006000",
    "storage": {
      "0x0000000000000000000000000000000000000000000000000000000000000000": "0x0000000000000000000000000000000000000000000000000000000000000001"
    }
  }
}

Trusted Selector Rules

Simulation selectors use trusted-mode selector semantics:

• latest: current local head
• pending, safe, finalized: aliases of latest
• earliest: block 0, accepted only while the current head is genesis
• numeric quantity: accepted only when equal to the current local head

Malformed selectors and selectors that resolve to a non-head block return -32602.

Example: eth_call

Request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_call",
  "params": [
    {
      "to": "0x0000000000000000000000000000000000000001",
      "data": "0x70a08231000000000000000000000000f39fd6e51aad88f6f4ce6ab8827279cfffb92266"
    },
    "latest"
  ]
}

Response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x0000000000000000000000000000000000000000000000000000000000000000"
}

Example: eth_estimateGas

Request:

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "eth_estimateGas",
  "params": [
    {
      "from": "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
      "to": "0x0000000000000000000000000000000000000001",
      "data": "0x"
    }
  ]
}

Response:

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": "0x5208"
}

Related Pages

• Core Reads
• Transactions And Mining
• ZEVM Controls
• Unsupported And Deferred