ASP.NET Controls

UI controls can help developers quickly build web apps. That is why such kind of library, suite, components get popular. There are many open source libraries, but commercial licenses usually provide more features, more controls and premium support.

.NET controls not only enable developers to build applications with intuitive user interfaces but also enhances productivity. While Microsoft provides standard set of controls with Visual Studio, third party suites contain numerous controls with wide range of unique features for the development of applications for PC and portable mobile devices.

Here is a list I am aware of:

www.telerik.com/devcraft‎
Familiar API, design-time support, app templates and more, using Kendo UI

www.componentone.com/controls
300+ Controls For Mobile, Web & Desktop.

https://www.infragistics.com/products/aspnet
Infragistics Ultimate UI for ASP.NET includes over 60 controls to help you create high-performing, full-featured enterprise apps that look great in any browser.

https://www.devexpress.com/
DevExpress provides best in class user interface controls for WinForms, ASP, MVC, WPF and Silverlight.

https://www.syncfusion.com/products/communitylicense
More than 800 controls and frameworks for web, desktop and mobile development.

ext.net
ASP.NET and ASP.NET MVC Controls and Components integrating the Sencha Ext JS JavaScript Library.

http://www.fineui.us
ASP.NET WebForms/MVC Components for Enterprise Apps, 50+ components with built-in AJAX support for desktop, tablets and phones. It is built based on jQuery with high performance and high quality, very popular in China.