eth_newBlockFilter | Monad

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.

POST /

eth_newBlockFilter

cURL

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": []
}
'

200

{
  "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

ethers.js

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