> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.

# eth_getFilterChanges | Base

> Base API method eth_getFilterChanges retrieves the changes of a filter since it was last accessed. Available on Base via Chainstack.

Base API method `eth_getFilterChanges` retrieves the changes of a filter since it was last accessed. This method is crucial for applications that need to monitor specific events or blocks on the Base blockchain.

<Warning>
  **Disclaimer**

  Note that the default interactive example in this page will not work as the filter will be expired.

  To test `eth_getFilterChanges` in this page, first create a new filter using one of the following:

  * [eth\_newFilter | Base](/reference/base-newfilter)
  * [eth\_newBlockFilter | Base](/reference/base-newblockfilter)

  Then use the fresh filter ID as the parameter for `eth_getFilterChanges`.
</Warning>

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## Parameters

* `filterId` — the ID of the filter whose changes are being queried. This ID is returned by filter creation methods such as `eth_newBlockFilter`, or `eth_newFilter`. For this example, a random value `"0x4a2b3c"` is used.

## Response

* `result` — an array of changes. For log filters, this will be an array of log entries. For block filters, it will be an array of block hashes. For pending transaction filters, it will be an array of transaction hashes. Each log entry object contains details such as the log index, transaction index, transaction hash, block hash, block number, address, data, and topics.

## Use case

The `eth_getFilterChanges` method is essential for:

* DApps that need to react to new events on the blockchain, such as token transfers or contract interactions.
* Services that monitor the blockchain for security or compliance reasons, needing to track specific transactions or blocks.
* Wallets and exchanges that require real-time information about transactions or blocks for processing or notification purposes.


## OpenAPI

````yaml /openapi/base_node_api/eth_getFilterChanges.json POST /2fc1de7f08c0465f6a28e3c355e0cb14
openapi: 3.0.0
info:
  title: eth_getFilterChanges example
  version: 1.0.0
  description: >-
    This is an API example for eth_getFilterChanges, a method to retrieve the
    changes of a filter since last  accessed.
servers:
  - url: https://base-mainnet.core.chainstack.com
security: []
paths:
  /2fc1de7f08c0465f6a28e3c355e0cb14:
    post:
      tags:
        - Ethereum Operations
      summary: eth_getFilterChanges
      operationId: getFilterChanges
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                jsonrpc:
                  type: string
                  default: '2.0'
                method:
                  type: string
                  default: eth_getFilterChanges
                id:
                  type: integer
                  default: 1
                params:
                  type: array
                  items:
                    type: string
                  default:
                    - '0x4a2b3c'
      responses:
        '200':
          description: The changes of the filter since last accessed
          content:
            application/json:
              schema:
                type: object
                properties:
                  jsonrpc:
                    type: string
                  id:
                    type: integer
                  result:
                    type: array
                    items:
                      type: object
                      properties:
                        removed:
                          type: boolean
                        logIndex:
                          type: string
                        transactionIndex:
                          type: string
                        transactionHash:
                          type: string
                        blockHash:
                          type: string
                        blockNumber:
                          type: string
                        address:
                          type: string
                        data:
                          type: string
                        topics:
                          type: array
                          items:
                            type: string

````