JavaScript!

CoffeeScript is a little language that compiles into JavaScript. Underneath all those awkward braces and semicolons, JavaScript has always had a gorgeous object model at its heart. CoffeeScript is an attempt to expose the good parts of JavaScript in a simple way. You can use any existing JavaScript library seamlessly from CoffeeScript (and vice-versa).

Now acquired by MICROSOFT. TypeScript is a language for application-scale JavaScript development. It is a typed superset of JavaScript that compiles to plain JavaScript in any browser, any host, any OS and it is Open Source.

Swift is a programming language for iOS, OS X, watchOS and tvOS apps that builds on the best of C and Objective-C, without the constraints of C compatibility. Swift adopts safe programming patterns and adds modern features to make programming easier, more flexible, and more fun. Swift’s clean slate, backed by the mature and much-loved Cocoa and Cocoa Touch frameworks, is an opportunity to reimagine how software development works.

The Objective-C language is a simple computer language designed to enable sophisticated object-oriented programming. Objective-C is defined as a small but powerful set of extensions to the standard ANSI C language. Its additions to C are mostly based on Smalltalk, one of the first object-oriented programming languages. Objective-C is designed to give C full object-oriented programming capabilities, and to do so in a simple and straightforward way.

LiveScript is a language which compiles down to JavaScript. It is a fork of Coco which is in turn derived from CoffeeScript. Like those two it has a relatively straightforward mapping to JavaScript. LiveScript is Coco but much more compatible with CoffeeScript, more functional, and more feature rich. LiveScript aims for increased expressiveness and code beauty.

Groovy is an agile and dynamic language for the Java Virtual Machine (JVM).

JRuby is a 100% Java implementation of the Ruby programming language running on the Java Virtual Machine (JVM).