debug_traceCall

The debug_traceCall method executes a call without creating a transaction on the blockchain and returns the trace of the call execution. This method simulates a transaction call against the blockchain state at a specific block, providing detailed execution traces including opcode-level information, gas usage, and state changes.

This method is invaluable for debugging smart contract interactions, optimizing gas consumption, and understanding transaction behavior before actually sending a transaction to the network. Developers can test contract calls with different parameters, analyze internal function calls, identify gas inefficiencies, and debug failed transactions in a safe environment without spending gas or altering blockchain state. The trace output can be customized using different tracers to focus on specific aspects of execution.

This method is available only on the full archive node.

Parameters

parameter	type	description
transaction	object (required)	The transaction call object
blockParameter	string (required)	Block number in hex format or one of the string tags: 'latest', 'earliest', or 'pending'
traceConfig	object (optional)	Configuration object to customize the trace output

Transaction Object Properties:

property	type	description
from	string (optional)	The address the call is sent from (20-byte hex string)
to	string (required)	The address the call is directed to (20-byte hex string)
gas	string (optional)	Gas provided for the call execution (hex)
gasPrice	string (optional)	Gas price for each paid gas (hex)
value	string (optional)	Value transferred with the call in wei (hex)
data	string (optional)	The data payload sent with the call (method signature and encoded parameters)

Trace Config Properties:

property	type	description
tracer	string (optional)	The type of tracer: 'callTracer', 'prestateTracer', '4byteTracer', or custom JavaScript tracer
timeout	string (optional)	Maximum time for the trace operation (e.g., '10s'). Defaults to '5s'
disableStorage	boolean (optional)	Set to true to disable storage capture for faster tracing
disableMemory	boolean (optional)	Set to true to disable memory capture
disableStack	boolean (optional)	Set to true to disable stack capture
enableMemory	boolean (optional)	Set to true to enable memory capture (opposite of disableMemory)
enableReturnData	boolean (optional)	Set to true to enable return data capture

Return Object

The method returns detailed trace information with structure depending on the tracer used:

With default tracer:

gas - number: Gas used by the execution
failed - boolean: Whether the execution failed
returnValue - string: The return data from the execution
structLogs - array: Array of opcode execution steps, each containing pc (program counter), op (opcode), gas (remaining gas), gasCost (cost of operation), depth (call depth), stack (execution stack), memory (execution memory), and storage (modified storage)

With callTracer:

type - string: The type of the call (CALL, CREATE, DELEGATECALL, etc.)
from - string: The address the call is from
to - string: The address the call is to
value - string: The value transferred
gas - string: The gas provided
gasUsed - string: The gas actually used
input - string: The input data
output - string: The output data
calls - array: An array of nested calls made during execution

Request Example

Request

Response Example

Response