The best free alternative to Kendo UI is UIkit, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 10 alternatives to Kendo UI and many of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Kendo UI are Semantic UI (Free, Open Source), jQuery UI (Free, Open Source), DevExtreme (Free Personal, Open Source) and GroundworkCSS (Free, Open Source).
A very easy to use, cross platform, jQuery based UI toolkit, that's still small in size, has the features you need, and doesn't get in your way of doing things ! jKit is framework js for easiest developpement like twitter bootstrap.
Kube is one of the world's most advanced and flexible frameworks. Kube helps you spend less time on routine tasks and more time creating amazing products. Focus on success, and Kube will cover the technology behind it.