Trace methods

Infura provides access to the following trace API methods to allow users to gain insights into the execution of smart contracts and transactions:

• trace_block
• trace_call
• trace_callMany
• trace_transaction
• trace_filter

info

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

When tracing transactions, the trace diagnostic options are trace and stateDiff.

info

trace_block, trace_filter, and trace_transaction returns trace information, whereas trace_call and trace_callMany allow you to use the trace or stateDiff diagnostic options when tracing calls or transactions.

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.
callType	Whether the transaction is call or create.
from	Address of the transaction sender.
gas	Gas provided by sender.
input	Transaction data.
to	Target of the transaction.
value	Value transferred in the transaction.
result	Transaction result.
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.
subTraces	Traces of 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.
type	Whether the transaction is a CALL or CREATE series 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.