Java
Free
Java is a general-purpose computer programming language.
Ruby
Open Source
Ruby is a dynamic, reflective, object-oriented, general-purpose programming language.
Scala
Open Source
Scala is a general-purpose programming language providing support for functional programming and a strong static type system.
REBOL
Free
Rebol is a cross-platform data exchange language and a multi-paradigm dynamic programming language.
Squirrel (programming language)
Open Source
Squirrel is a high level imperative, object-oriented programming language.
JavaScript
Open Source
JavaScript is a high-level, dynamic, untyped, and interpreted run-time language.
Lua
Open Source
Lua is a powerful and fast programming language that is easy to learn and use and to embed into your application.
Groovy
Open Source
Apache Groovy is a powerful, optionally typed and dynamic language, with static-typing and static compilation capabilities, for the Java platform.
Kotlin
Open Source
Kotlin is a statically-typed programming language that runs on the Java virtual machine.
Compare jRuby with alternatives
Compare Squirrel (programming language) and jRuby and decide which is most suitable for you.