RhoMobile is described as 'Cross-platform framework for creating mobile and desktop apps for iOS, Android, WinCE, Sailfish OS, Windows, Linux and OS X' and is an app in the Development category. There are more than 25 alternatives to RhoMobile for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is Qt, which is both free and Open Source. Other great apps like RhoMobile are Electron (Free, Open Source), Flutter (Free, Open Source), Apache Cordova (Free, Open Source) and React Native (Free, Open Source).
Qt is a cross-platform application framework that is widely used for developing application software that can be run on various software and hardware platforms with little or no change in the underlying codebase, while having the power and speed of native applications.
Haskell is an advanced purely-functional programming language. An open-source product of more than twenty years of cutting-edge research, it allows rapid development of robust, concise, correct software.
Haxe is an open source toolkit based on a modern high level strictly typed programming language, a state-of-the-art light-speed cross-compiler, a complete cross-platform standard library, and ways to access to each platform's native capabilities.
Cross platform development tools for native iOS, Android, desktop and server applications. B4X is a Rapid Application Development (RAD) tool for real world apps. The programming language is a modern version of Visual Basic.