eth_subscribe - Robinhood

Example code for the eth_subscribe JSON-RPC method. Complete guide to using the eth_subscribe JSON-RPC method in GetBlock.io Web3 documentation.

Subscribes to events over WebSocket. Returns a subscription ID; matching events arrive as separate WebSocket messages with that ID. Supported subscription types: newHeads (new block headers), logs (filtered event logs), newPendingTransactions (pending tx hashes), syncing (sync status changes). With Robinhood Chain's 100ms block cadence, newHeads fires very frequently — ensure your consumer can handle the throughput.

WebSocket-only method.

Parameters

Parameter	Type	Required	Description
type	string	Yes	Subscription type — one of newHeads, logs, newPendingTransactions, syncing
filter	object	No	For logs subscriptions: filter object with address and topics

Request Example

cURL

# WebSocket-only method. Use wscat (or similar) to connect first:
wscat -c 'wss://shared.us-east-1.getblock.io/<ACCESS-TOKEN>/'

# Then send:
{"jsonrpc": "2.0", "method": "eth_subscribe", "params": ["newHeads"], "id": "getblock.io"}

JavaScript (Axios)

import WebSocket from 'ws';

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

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

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

Python (Requests)

import asyncio
import json
import websockets

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

asyncio.run(main())

Rust (Reqwest)

use tokio_tungstenite::connect_async;
use tokio_tungstenite::tungstenite::Message;
use serde_json::json;
use futures_util::{SinkExt, StreamExt};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let (mut ws_stream, _) = connect_async("wss://shared.us-east-1.getblock.io/<ACCESS-TOKEN>/").await?;

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "eth_subscribe",
        "params": [
                "newHeads"
        ],
        "id": "getblock.io"
});
    ws_stream.send(Message::Text(payload.to_string())).await?;

    while let Some(msg) = ws_stream.next().await {
        println!("{:?}", msg?);
    }
    Ok(())
}

Response Example

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0xcd0c3e8af590364c09d0fa6a1210faf5"
}

Response Parameters

Field	Type	Description
result	string	Subscription ID — match incoming notifications by this and use to call eth_unsubscribe

Use Cases

• Real-time block notifications for indexers and explorers

• Live Stock Token transfer tracking (subscribe to logs filtered to Stock Token contracts)

• Mempool monitoring (newPendingTransactions)

• Detecting sync state changes

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid <ACCESS-TOKEN>
-32602	Invalid params	Request parameters are missing or malformed
-32603	Internal error	Server-side error while processing the request
429	Too Many Requests	Rate limit exceeded for your plan
-32600	Invalid Request	eth_subscribe called over HTTP; use WebSocket
-32602	Invalid subscription type	Type is not one of the four supported

SDK Integration

ethers.js

import { ethers } from 'ethers';

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

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

// For 'logs' subscription with a filter:
// provider.on({ address: '0x...', topics: [...] }, (log) => { ... });

viem

import { createPublicClient, webSocket } from 'viem';

const client = createPublicClient({
    transport: webSocket('wss://shared.us-east-1.getblock.io/<ACCESS-TOKEN>/')
});

// Subscribe to new blocks:
const unwatch = client.watchBlocks({
    onBlock: block => console.log('New block:', block.number)
});
// Call unwatch() when done.