# Extensions and themes

Warning noteWidget and custom component support have been removed as of Qlik Sense August 2021. See [Deprecation Notice – Qlik Sense Widgets and Custom Components FAQ](https://community.qlik.com/t5/Knowledge-Base/Deprecation-Notice-Qlik-Sense-Widgets-and-Custom-Components-FAQ/ta-p/1790713) for more information.

## Extensions

Visualization extensions use the same set of technologies as standard Qlik Sense visualizations, and if developed properly, the handling of them is identical to standard visualizations.

### Visualization extensions

### Get started building visualization extensions

### Get started building extensions with Dev Hub

## Custom themes

Themes are used to style your Qlik Sense apps and you can create your own custom themes based on your company standards.

### Custom themes

### Get started building custom themes

### Installing custom themes

## API reference

See [API reference for Windows](https://help.qlik.com/en-US/sense-developer/November2025/Content/Sense_Helpsites/APIs-and-SDKs.htm).