# Custom Groups

Custom groups are pre-defined, Prolific-curated sets of participants that can be used as filters in your studies.

To use custom groups in your studies:

<Steps>
  <Step>
    Get available custom groups using the filters endpoint:

    ```
    GET /api/v1/filters/?filter_tag=custom-group
    ```
  </Step>

  <Step>
    To check the number of participants in the custom group,please go here:
  </Step>

  <Step>
    Use the custom group in your study:

    ```
    {
      "filters": [
        {
          "filter_id": "javascript",
          "selected_values": ["0"]
        }
      ],
    }
    ```
  </Step>
</Steps>