In the dynamic world of blockchain, staying updated with transactions involving smart contracts is essential for maintaining a secure and efficient platform. Tatum's OUTGOING_INTERNAL_TX notification type offers a powerful solution to help you track outgoing native balance updates on a monitored smart contract.

How to do it?

curl -i -X POST \
  https://api.tatum.io/v4/subscription?type=mainnet \
  -H 'Content-Type: application/json' \
  -H 'x-api-key: <YOUR-API-KEY>' \
  -d '{
    "type": "OUTGOING_INTERNAL_TX",
    "attr": {
      "address": "0xF64E82131BE01618487Da5142fc9d289cbb60E9d",
      "chain": "ETH",
      "url": "https://<YOUR_WEBHOOK_URL>"
    }
  }'

import { TatumSDK, Ethereum, Network } from '@tatumio/tatum'

(async () => {
    const tatum = await TatumSDK.init<Ethereum>({network: Network.ETHEREUM})
    
    const monitoredSmartContract = '0xF64E82131BE01618487Da5142fc9d289cbb60E9d'
    
    const subscription = await tatum.notification.subscribe.outgoingInternalTx({
        address: monitoredSmartContract,
        url: 'https://<YOUR_WEBHOOK_URL>' // replace with your handler URL
    })
    console.log(`Now you will be notified about all outgoing ETH transactions on ${monitoredSmartContract}`)
})()

What does the fired webhook look like?

The fired notification webhook you will receive in your webhook listener will have the following format.

{
  "currency": "ETH",
  "chain": "ethereum-mainnet",
  "txId": "0x062d236ccc044f68194a04008e98c3823271dc26160a4db9ae9303f9ecfc7bf6",
  "blockNumber": 2913059,
  "subscriptionType": "OUTGOING_INTERNAL_TX",
  "mempool": false,
  "address": "0xF64E82131BE01618487Da5142fc9d289cbb60E9d",
  "counterAddress": "0x690B9A9E9aa1C9dB991C7721a92d351Db4FaC990",
  "amount": "0.001"
}

Which blockchain networks are supported?

Blockchain	Mainnet	Testnet
Ethereum	Network.ETHEREUM	Network.ETHEREUM_SEPOLIA, Network.ETHEREUM_HOLESKY
Polygon	Network.POLYGON	Network.POLYGON_MUMBAI
Binance Smart Chain	Network.BINANCE_SMART_CHAIN	Network.BINANCE_SMART_CHAIN_TESTNET
Flare	Network.FLARE	Network.FLARE_COSTON, Network.FLARE_COSTON_2, Network.FLARE_SONGBIRD
Celo	Network.CELO	Network.CELO_ALFAJORES
Klaytn	Network.KLAYTN	Network.KLATN_BAOBAB
Tezos	Network.TEZOS	Network.TEZOS_TESTNET
Tron	Network.TRON	Network.TRON_SHASTA