Let us look at what is being offered as part of the Kendo UI core package. Telerik has published a nice comparison table which we will use as the basis for our analysis.
A collection of smaller widgets like Textboxes, Calendars, Color Pickers, Menus, Buttons, and Combo Boxes, along with core frameworks like Data Source, MVVM, Single-Page App, and Drag and Drop.
All the larger widgets like the Chart, Grid, Scheduler, Gauge, and Map. These can be summarized as everything needed to build a non-trivial/commercial web or mobile application.
The bottom-line is that you can get started developing with KendoUI core (or any of several freely available frameworks), but for any non-trivial web or mobile application you would definitely need alternatives.
We see this as a marketing effort to improve the adoption of their commercial offerings.
We offer a $1 hobbyist license for our full Essential JS product. This license offers a full license to all our 70+ JavaScript controls for web and mobile development. The license also permits usage for commercial purposes with the restriction that it can only be used by individuals and not organizations. You also get access to commercial support for a full year. This is not a onetime offer, and you can renew at the end of the year for the same price. The hobbyist license can be purchased through the following link:
http://www.syncfusion.com/sales/offers/js-hobbyist
Online demos of the 70+ web, mobile, and data visualization controls available in Essential JS can be seen here:
https://js.syncfusion.com/demos/web/
We hope that the above information provides enough clarity to our customers in choosing between the KendoUI core and Syncfusion Essential JS libraries. Essential JS is a far superior value.