When comparing Kendo UI vs Polymer, the Slant community recommends Polymer for most people. In the question“What are the best JavaScript libraries for building a UI?” Polymer is ranked 4th while Kendo UI is ranked 14th. The most important reason people chose Polymer is:
It provides a base component.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free Core tools
Kendo UI is separated into a commercial and open source frameworks. The core of Kendo UI is in the open source frameworks, but some usability and benefits of Kendo UI are lost without the commercial version.
Pro Platform-based UI
Kendo knows what device it is being viewed on so it can adjust the UI accordingly. If a user is on a PC the user will see things differently than on a mobile device. Between iOS and Android the user will also notice a different as it pulls from the core UI of those core systems.
Pro Theme Builder
An interactive tool that has been created to customize an apps theme. Users are able to select from many pre-defined themes, edit them, and download the theme to bring into a project.
Pro Various basic components
It provides a base component.
Pro HTML markup is not string
HTML markup as it can be a non-string.
Pro Flex layout components
It provides Flex layout components.
Pro CSS is easy to apply
CSS can be applied far more comfortably than React.
Pro No need for special debugging tools
The presence od specialized debugging tools are advertised by competitors. The all features of web components are natively supported by browser embedded development tools.
Pro Excellent routing
The router is embedded into CLI for project creation and covers as web as Progressive web app, also fused with Polymer layouts out of the box. The shop template for CLI has a complete solution including the routing.
Pro Complete web app stack support
Full app stack from data tier to routing, progressive web app, responsive layouts makes no need to seek outside of Polymer ecosystem for application features.
In addition to waste set of mature web components in Polymer Elements along with Vaadin Elements there are thousands of web components in the wild comparable to jQuery plugins set.
Pro Excellent documentation
Polymer guides you as with tools (cli, build environment, app templates,..) as with complimentary documentation on all phases of app development from creation of app as progresive web app to production deployment instructions.
As Polymer is standards based, the whole community around those standards also helping in documentation and support.
Pro Based on web components
Web Components are a collection of specifications released by W3C as a way to reduce the complexity of web apps by creating reusable components. Browser support is currently poor for web components, however Polymer is developed to make web components compatible with modern browsers.
Pro API is easy to understand, based on standard
The Polymer APIs are split on application layers and follow standards on all possible ways: Web Components, CSS variables, async API via Promises and so on.
Cons
Con Expensive commercial tools [$699, $1,499]
The other core tools developed with Kendo are the commercial tools. There is the Professional version for $699 that will result in more jQuery UI widgets and client support. The $1499 "DevCraft" Complete edition gets developers the DevCraft .NET toolbox, testing and debugging frameworks and applications, as well as priority support.
Con No server-side rendering
Polymer does not support server-side rendering. This results in higher loading times, more HTTP requests and it's not very SEO friendly, since search engines have no way of indexing a page if it's not rendered in the server.