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POST
eth_newBlockFilter
curl --request POST \
  --url https://monad-testnet.core.chainstack.com/9c5b265f20b3ea5df4f54f70eb74b800/ \
  --header 'Content-Type: application/json' \
  --data '
{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "eth_newBlockFilter",
  "params": []
}
'
{
  "jsonrpc": "<string>",
  "id": 123,
  "result": "<string>"
}
Monad API method that creates a filter in the node to notify when a new block arrives. Use eth_getFilterChanges to poll for new blocks.
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​
Parameters

  • none

​
Response

  • result — the filter ID, used to poll for new blocks with eth_getFilterChanges.

​
eth_newBlockFilter code examples

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

const provider = new ethers.JsonRpcProvider("CHAINSTACK_NODE_URL");

async function createBlockFilter() {
  const filterId = await provider.send("eth_newBlockFilter", []);
  console.log("Filter ID:", filterId);

  // Poll for new blocks
  setInterval(async () => {
    const changes = await provider.send("eth_getFilterChanges", [filterId]);
    if (changes.length > 0) {
      console.log("New blocks:", changes);
    }
  }, 2000);
}

createBlockFilter();

​
Use case

A practical use case for eth_newBlockFilter is building applications that need to react to new blocks as they are mined, such as block explorers, monitoring tools, or HTTP-only clients that can’t hold a persistent WebSocket connection. For real-time streaming, prefer eth_subscribe("newHeads") over WebSocket — see the event-monitoring tutorial.

Body

application/json
​
id
integer
default:1
​
jsonrpc
string
default:2.0
​
method
string
default:eth_newBlockFilter
​
params
array

Response

200 - application/json

A filter ID that can be used with eth_getFilterChanges to poll for new blocks

​
jsonrpc
string
​
id
integer
​
result
string

The filter ID

Last modified on May 18, 2026