eth_subscribe("newPendingTransactions") | Avalanche

Avalanche API method that allows developers to receive real-time notifications regarding new pending transactions on the Avalanche blockchain. The application will receive notifications whenever new pending transactions are identified.


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  • string โ€” keyword identifying the type of event to subscribe to, newPendingTransactions in this case.


  • subscription โ€” the subscription ID.
  • string โ€” the hash of a pending transaction.

eth_subscribe("newPendingTransactions") code examples


Note that subscriptions require a WebSocket connection and WebSocket cat for you to use this method in the console.

Install WebSocket cat with:

npm install -g wscat

# Wait for the connection to be established

Connected (press CTRL+C to quit)

> {"id":1,"jsonrpc":"2.0","method":"eth_subscribe","params":["newPendingTransactions", true]}
const WebSocket = require('ws');

const webSocket = new WebSocket('CHAINSTACK_WSS_URL');

async function subscribeToNewPendingTransactions() {
  const request = {
    id: 1,
    jsonrpc: '2.0',
    method: 'eth_subscribe',
    params: ['newPendingTransactions', true],

  const onOpen = (event) => {

  const onMessage = (event) => {
    const response = JSON.parse(;

  try {
    webSocket.addEventListener('open', onOpen);
    webSocket.addEventListener('message', onMessage);
  } catch (error) {


This will generate a continuous stream of data displaying new pending transactions as they are added to the mempool.

Use eth_unsubscribe to remove the subscription.

Use case

The eth_subscribe("newPendingTransactions") method on Avalanche is used to subscribe to the network and receive real-time updates on all new pending transactions on the network. This can be useful in a variety of real-world scenarios, including:

  • Trading applications. A trading application can use this method to keep track of any new transactions that are being made on the network. This can be particularly useful for high-frequency trading, where speed is crucial. By subscribing to this method, the trading application can receive real-time updates on new trades, allowing it to quickly respond and execute trades.

  • Monitoring tools. Monitoring tools can use this method to keep track of any suspicious activity on the network. By subscribing to this method, monitoring tools can receive real-time updates on any new pending transactions and quickly take action if necessary.

  • Payment processors. Payment processors can use the eth_subscribe("newPendingTransactions") method to monitor incoming transactions from their customers. This can be particularly useful for businesses that rely on blockchain technology to process payments, as it allows them to track incoming payments in real time. By subscribing to this method, payment processors can receive instant notifications when new payments are received, which can help streamline their payment processing workflows.