eth_subscribe - BSC

Example code for the eth_subscribe JSON-RPC method. Complete guide on how to use eth_subscribe JSON-RPC in GetBlock Web3 documentation.

This method creates a subscription for real-time event notifications on the Celo network.

This requires a WebSocket connection and is ideal for tracking new blocks, pending transactions, or contract events with Celo's fast ~1 second block times.

Parameters

Parameter	Type	Required	Description
subscriptionType	string	Yes	Type: "newHeads", "logs", "newPendingTransactions"
options	object	No	Filter options (for "logs" type)

Request Example

JavaScript (newHeads)

subscribe-newHeads.js

const WebSocket = require('ws');

const ws = new WebSocket('wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

ws.on('open', () => {
  ws.send(JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_subscribe',
    params: ['newHeads']
  }));
});

ws.on('message', (data) => {
  console.log(JSON.parse(data));
});

JavaScript (logs - cUSD Transfers)

subscribe-logs-cusd.js

const WebSocket = require('ws');

const ws = new WebSocket('wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

ws.on('open', () => {
  ws.send(JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_subscribe',
    params: [
      'logs',
      {
        address: '0x765DE816845861e75A25fCA122bb6898B8B1282a',
        topics: ['0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef']
      }
    ]
  }));
});

ws.on('message', (data) => {
  console.log('cUSD Transfer:', JSON.parse(data));
});

Python (websockets)

subscribe_newHeads.py

import asyncio
import websockets
import json

async def subscribe():
    uri = "wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/"
    async with websockets.connect(uri) as ws:
        await ws.send(json.dumps({
            "jsonrpc": "2.0",
            "id": 1,
            "method": "eth_subscribe",
            "params": ["newHeads"]
        }))
        
        async for message in ws:
            print(json.loads(message))

asyncio.run(subscribe())

Response Example

Result

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x9cef478923ff08bf67fde6c64013158d"
}

Subscription Notification

{
  "jsonrpc": "2.0",
  "method": "eth_subscription",
  "params": {
    "subscription": "0x9cef478923ff08bf67fde6c64013158d",
    "result": {
      "number": "0x1d9f2a8",
      "hash": "0x4e3a375...",
      "parentHash": "0xb903239...",
      "timestamp": "0x65a1b2c3"
    }
  }
}

Response Definition

Field	Type	Description
result	string	Subscription ID

Use Cases

• Real-time block notifications

• Live stablecoin transfer tracking

• Pending transaction monitoring

• DeFi event streaming

Error Handling

Error Code	Description
-32602	Invalid subscription type
-32603	Internal error

SDK Integration

Ethers.js

ethers-subscribe.js

const { ethers } = require('ethers');

const provider = new ethers.WebSocketProvider('wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

provider.on('block', (blockNumber) => {
  console.log('New block:', blockNumber);
});

Viem

viem-watchBlocks.js

import { createPublicClient, webSocket } from 'viem';
import { celo } from 'viem/chains';

const client = createPublicClient({
  chain: celo,
  transport: webSocket('wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/')
});

const unwatch = client.watchBlocks({
  onBlock: block => console.log('Block:', block.number)
});