jQuery UI is a Windows program package that includes a curated catalog of user interface interactions, effects, widgets and themes which are built on top of the jQuery JavaScript Library. It is a convenient tool for people who want to develop interactive web-apps and fine-tune their project. If you need to store the program code, you may use TortoiseSVN.

Using options

After launch, each plugin has a default configuration aimed at basic and common use cases. If you want the component to behave differently, you can override each of its settings via options. These are a set of properties passed into the widget as an argument. For example, the slider has an option for orientation. This means, you have the ability to specify whether it should be positioned horizontally or vertically by inputting a corresponding argument.

Theme customization

jQuery UI also allows you to design your own themes. You can access this feature by either clicking the Themes link in the navigation menu or simply going to ThemeRoller. This component provides a custom interface for designing all of the elements used by various widgets. As you tweak the levers in the left column, the applets on the right reflect the changes in real time. The Gallery tab offers a number of ready-made themes that you can tweak or download as they are.

Features

free to download and use;
compatible with modern Windows versions;
gives you the ability to develop interactive web-apps;
provides a wide range of customizable UI widgets;
allows you to design your own themes.