When comparing Onsen UI vs Codename One, the Slant community recommends Codename One for most people. In the question“What are the best frameworks for developing cross-platform mobile apps?” Codename One is ranked 5th while Onsen UI is ranked 9th.
Ranked in these QuestionsQuestion Ranking
Pro Open source and free
Onsen UI is open source, and completely free to use.
Pro Can be used for web apps as well
Onsen UI is usable for classic web development as well as mobile.
Pro Large selection of components
Onsen UI provides a wide selection of components that are ready to use out of the box and are easily customizable.
Pro Easy to use
Onsen UI provides very clear, well-written and detailed documentation.
It uses popular technologies that are likely already familiar to developers (such as jQuery and Angular).
The framework is semantic and intuitive to use, making it quite fast to learn.
Pro Supports React
React is the most trending front-end UI framework, naturally supporting that is a plus.
Pro High performance
Pro Open source
Pro Highly customizable
By utilizing lightweight component architecture and the built in graphical designer and theming options you are able to customize a good looking app on any platform.
Pro Java 8 support
Pro Works with all IDEs
Works with NetBeans, Eclipse, IntelliJ, etc.
Pro Multi-platform development environments (via build server)
You can even use Linux desktops to build native iOS apps, no need for a Mac.
Pro Vibrant & helpful community
Pro Attractive pricing
It is possible to build production grade apps even with the free version. Pricing is decent when compared to competitors like Xamarin.