eth_newBlockFilter - Blast

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

This method creates a filter that reports the hashes of new blocks as they are produced, and returns a filter ID.

Parameters

This method does not require any parameters. Send the request with an empty params array.

Request

cURL

curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "eth_newBlockFilter",
    "params": [],
    "id": "getblock.io"
}'

Axios

example.js

const axios = require('axios');

const response = await axios.post('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'eth_newBlockFilter',
    params: [],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

console.log(response.data.result);

Request

example.py

import requests

response = requests.post(
    'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'eth_newBlockFilter',
        'params': [],
        'id': 'getblock.io'
    }
)

print(response.json())

Rust

example.rs

use reqwest::Client;
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let response = client
        .post("https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "eth_newBlockFilter",
            "params": [],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x9f3c7a1e5d2b8046c1a3f5e7d9b0c2a4"
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	string	Hex-encoded filter ID

Use Cases

• New Block Polling: Detect new blocks without a WebSocket subscription

• Cadence Sampling: Observe the ~1 second block cadence via polling

• Trigger Pipelines: Kick off work when a new block appears

• Lightweight Watching: Track the chain tip where subscriptions are unavailable

Error Handling

Error Code	Message	Description
-32603	Internal error	The node failed to register the block filter
-32601	Method not found	Filters are disabled on the client build

Web3 Integration

Ethers.js

ethers-example.js

import { ethers } from 'ethers';

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

provider.on('block', (blockNumber) => console.log(blockNumber));

Viem

viem-example.js

import { createPublicClient, http } from 'viem';

const client = createPublicClient({
  transport: http('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/')
});

const unwatch = client.watchBlockNumber({ onBlockNumber: (n) => console.log(n) });