trace_replayTransaction

The trace_replayTransaction method allows you to replay a transaction and retrieve a variety of trace information including execution trace, VM trace, and state changes. This method provides more detailed information than trace_transaction by showing how the transaction changed the state.

Use Cases

Debugging complex transactions with state changes
Analyzing gas consumption for optimization
Tracing internal calls between contracts
Understanding how storage was modified by a transaction
Verifying the execution of complex logic flows
Security auditing with full state transition detail
Analyzing revert reasons with detailed context
Investigating memory and storage access patterns
Validating contract behavior as part of audit reviews
Optimizing contract code based on execution patterns

Method Details

This method replays a transaction and returns detailed trace information including VM trace and state differences.

Response Example

1{
2	"jsonrpc": "2.0",
3	"id": 1,
4	"result": {
5		"output": "0x0000000000000000000000000000000000000000000000000000000000000001",
6		"stateDiff": {
7			"0x1234567890123456789012345678901234567890": {
8				"balance": {
9					"*": {
10						"from": "0x100",
11						"to": "0x110"
12					}
13				},
14				"code": "=",
15				"nonce": {
16					"*": {
17						"from": "0x10",
18						"to": "0x11"
19					}
20				},
21				"storage": {
22					"0x0000000000000000000000000000000000000000000000000000000000000001": {
23						"*": {
24							"from": "0x0000000000000000000000000000000000000000000000000000000000000000",
25							"to": "0x0000000000000000000000000000000000000000000000000000000000000001"
26						}
27					}
28				}
29			}
30		},
31		"trace": [
32			{
33				"action": {
34					"callType": "call",
35					"from": "0x83806d539d4ea1c140489a06660319c9a303f874",
36					"gas": "0x1a1f8",
37					"input": "0x",
38					"to": "0x1c39ba39e4735cb65978d4db400ddd70a72dc750",
39					"value": "0x7a16c911b4d00000"
40				},
41				"result": {
42					"gasUsed": "0x2982",
43					"output": "0x"
44				},
45				"subtraces": 2,
46				"traceAddress": [],
47				"type": "call"
48			}
49		],
50		"vmTrace": {
51			"code": "0x606060...",
52			"ops": [
53				{
54					"cost": 3,
55					"ex": {
56						"mem": null,
57						"push": ["0x60"],
58						"store": null,
59						"used": 16723979
60					},
61					"pc": 0,
62					"sub": null
63				}
64			]
65		}
66	}
67}

Trace Types

The traceTypes parameter accepts an array of the following values:

trace: The basic trace of transaction execution
vmTrace: A detailed trace of the EVM execution
stateDiff: State changes resulting from the transaction

You can request any combination of these trace types.

State Diff Format

The state diff format uses the following symbols:

"=": No change in the value
"+": The value was created
"-": The value was deleted
"*": The value was modified, with "from" and "to" values

Important Notes

This method requires trace APIs to be enabled on the Ethereum node
Not all Ethereum clients support this method (primarily OpenEthereum/Nethermind)
The response can be very large, especially with vmTrace enabled
For simple trace information without state changes, use trace_transaction instead
The method is computationally intensive and may take time to complete
Historical transactions can only be traced if the node maintains archive data
Different traceTypes significantly affect response size and computation time
For debugging simpler transactions, trace_transaction may be sufficient
State diffs are particularly valuable for understanding storage changes
Transactions that revert will show state changes up to the revert point