Ethereum trace methods

info

Trace API is an open beta feature, available to paying Infura customers.

Infura provides access to trace API methods that provide insights into the execution of smart contracts and transactions.

Method	Diagnostic options
trace_block	trace
trace_call	trace, stateDiff
trace_callMany	trace, stateDiff
trace_transaction	trace
trace_filter	trace

caution

Trace responses are handled generically to enable support of additional fields beyond those documented here. This requires graceful handling.

trace

Provides an ordered trace of the instructions executed by the Ethereum Virtual Machine (EVM) during the execution of a smart contract transaction. Excludes precompiled contracts.

Trace example

"trace":[
  {
    "action":{
      "callType":"call",
      "from":"0xfe3b557e8fb62b89f4916b721be55ceb828dbd73",
      "gas":"0xffadea",
      "input":"0x",
      "to":"0x0100000000000000000000000000000000000000",
      "value":"0x0"
    },
    "result":{
      "gasUsed":"0x1e",
      "output":"0x"
    },
    "subtraces":0,
    "traceAddress":[
    ],
    "type":"call"
  }
]

Key	Value
action	Transaction details.
- creationMethod	Opcode used during contract creation: create or create2. Returned for create operations.
- callType	Whether the transaction is call, staticcall, delegatecall. Returned for call operations.
- from	Address of the transaction sender.
- gas	Gas provided by sender.
- input	Transaction data. Returned for call operations.
- init	Contract initialization code. Returned for create operations.
- to	Target of the transaction. Returned for call operations.
- value	Value transferred in the transaction.
blockHash	Hash of the block containing this trace.
blockNumber	Block number containing this trace.
result	Transaction result.
- address	Address of the newly created contract. Returned for create operations.
- code	Bytecode of the newly created contract. Returned for create operations.
- gasUsed	Gas used by the transaction. Includes any refunds of unused gas.
- output	Return value of the contract call. Contains only the actual value sent by a RETURN operation. If a RETURN was not executed, the output is empty bytes. Returned for call operations.
subtraces	Number of sub-traces (nested contract calls) made by the transaction.
traceAddress	Tree list address of where the call occurred, address of the parents, and order of the current sub call.
transactionHash	Hash of the transaction.
transactionPosition	Transaction position within the block.
type	Whether the transaction is a call or create operation.

stateDiff

Displays state changes in the requested block for each transaction, represented as a map of accounts to an object. Lists the balance, code, nonce, and storage changes from immediately before the transaction to after the transaction. For the key:value pairs:

• + indicates the field didn’t exist before and now has the specified value
• - indicates a deleted value
• * has a from and a to value

An absent value is distinct from zero when creating accounts or clearing storage. For example, when clearing storage, an absent value means that a particular storage slot has not yet been assigned a value, while a zero value means that the storage slot has been assigned and set to zero.

stateDiff example

"stateDiff":{
  "0xfe3b557e8fb62b89f4916b721be55ceb828dbd73":{
    "balance":{
      "*":{
        "from":"0xffffffffffffffffffffffffffffffffc3e12a20b",
        "to":"0xffffffffffffffffffffffffffffffffc3dc5f091"
      }
    },
    "code":"=",
    "nonce":{
      "*":{
        "from":"0x14",
        "to":"0x15"
      }
    },
    "storage":{
    }
  }
}

Key	Value
balance	Change of balance event.
balance.from	Balance before the transaction.
balance.to	Balance after the transaction.
code	Changes to code. None in this example.
nonce	Change of nonce.
nonce.from	Nonce before the transaction.
nonce.to	Nonce after the transaction.
storage	Changes to storage. None in this example.