You can check your UI version in System Settings → System → System Update → Current Version.
One of the most popular searches related to “UI download link” is for custom themes. Unlike the 3DS or Wii U, the Nintendo Switch does not natively support custom themes (no official theme shop like the 3DS had). nintendo switch ui download link
If you simply want the latest official UI features (like the “Sort by Software” option added in v18.0.0), follow this guide: You can check your UI version in System
Current latest firmware (as of 2025): v19.0.0 – adds “Virtual Game Cards” UI and improved menu load times. Current latest firmware (as of 2025): v19