# Custom Configuration

CKFinder provides many configuration options that can be changed to customize the application. For details please check the documentation.

In the example below the following options are set:

- `id` sets the instance ID to `custom-instance-id`,
- `thumbnailDefaultSize` sets the default thumbnail size to 400px after CKFinder is started,
- `width` sets the widget width to 100% to use all available space,
- `height` sets the widget height to 500 pixels.

    CKFinder.widget( 'ckfinder-widget', {
        id: 'custom-instance-id',
        thumbnailDefaultSize: 400,
        width: '100%',
        height: 500
    } );