This document shows methods available to look up internal transactions on an Avalanche L1 or the C-Chain
What Are Internal Transactions?
Internal transactions are transfers of native tokens by a smart contract. Unlike regular transactions, internal transactions are not recorded as separate, top-level transactions on the blockchain. Instead, they are embedded ("internally") within the transaction that triggered the smart contract execution. This can make them more challenging to track. Blockchain explorers and JSON-RPC APIs do not always make this information readily available. A common example of an internal transaction is the unwrapping (withdrawal) of a native token from a wrapping ARC20 smart contract (example: WAVAX on the C-chain mainnet and testnet).
How Can I Lookup Internal Transactions on the C-Chain?
For any given transaction hash, Tenderly offers detailed analysis of transfers occurring during a transaction. Use the following URL pattern for any chain that Tenderly indexes (currently includes Avalanche mainnet C-Chain and testnet C-Chain):
https://dashboard.tenderly.co/tx/<TX_HASH>
For example, this testnet C-chain transaction shows 0.01 WAVAX being unwrapped, with the withdrawal of 0.01 AVAX being sent as an internal transaction back to the requester's wallet address. Note the transaction value is 0 AVAX (no AVAX is being sent into the smart contract), however the "Native coins transferred" tab shows 0.01 AVAX being sent as an internal transaction.
How Can I Lookup Internal Transactions on an L1?
Tenderly does not actively index any L1 chains at this time. Instead, API calls can be made against a Developer RPC to obtain internal transaction values. A curl call follows this pattern:
$ curl -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"debug_traceTransaction","params":["<TX_HASH>", {"tracer": "callTracer"}],"id":1}' <DEVELOPER_RPC_URL>
Example for an existing L1:
curl --silent -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"debug_traceTransaction","params":["0xb8ff1fd593ad9002df66f0c8965b5755d02ec2d893ac81c1623a7f2b90f4b1b4", {"tracer": "callTracer"}],"id":1}' https://testnet-example.avax-test.network/ext/bc/yvnQuuRUBSTJjdsfowKtzXpYFd3yWH9cha25CABBGdGX1wP6G/rpc
Response:
{
"jsonrpc": "2.0",
"id": 1,
"result": {
"from": "0xd1aa63b599e39ec6b076ce5c052df6609134210a",
"gas": "0x8e04",
"gasUsed": "0x89c7",
"to": "0x20c5541eb19573f4c9044969de818706f70adbc7",
"input": "0x2e1a7d4d00000000000000000000000000000000000000000000000002c68af0bb140000",
"calls": [
{
"from": "0x20c5541eb19573f4c9044969de818706f70adbc7",
"gas": "0x8fc",
"gasUsed": "0x0",
"to": "0xd1aa63b599e39ec6b076ce5c052df6609134210a",
"input": "0x",
"value": "0x2c68af0bb140000",
"type": "CALL"
}
],
"value": "0x0",
"type": "CALL"
}
}
To find internal transactions, see each transaction within the "calls" portion of the JSON response. Any call response with "input" equal to "0x" with a non-zero "value" is an internal transaction. In this case, the hex value can be converted back to to a decimal value of AVAX (in this case a value of 0.2 AVAX) using Foundry's cast to-fixed-point command:
$ cast to-fixed-point 18 0x2c68af0bb140000
0.200000000000000000