What are the add-ons? Categorize them.

In addition to the components, themes, layouts, and data sources inbuilt into the core Vaadin library, many others are available as add-ons. Vaadin Directory offers a wide collection of add-ons for Vaadin, and the user may also find others from independent sources. Add-ons are also a way to share a user’s own components between projects. There are currently over a hundred and eighty add-ons available. They are divided to the following categories:

• UI components – These add new functionality to your user interfaces
• Data components – They interface various data sources to Vaadin components
• Themes –These add a fresh look to your application
• Miscellaneous –This comprises of everything else.

Most of the add-ons are free under the Apache 2.0 license, but some of them are commercial or dual licensed.