You've Got Choices
Our core supported languages are colored in green. The rest of the languages, colored in blue, are supported as well but have not been as thoroughly tested against the challenges on our site. As such, we cannot guarantee that all necessary third-party libraries required to solve every challenge are installed. This is where we rely on you, the users, to provide us with feedback if you feel one was omitted and should be included.
BASH
The Bourne-Again Shell
C
The C Programming Language
C++
The C++ Programming Language (originally C with Classes)
C#
This is currently disabled. We might enable support if there is enough player interest.
The C# Programming Language (we compile in Windows/.NET)
Go/Golang 1.10.2
compiled, conncurrent, imperative, structured
Haskell
Purely Functional, lazy/non-strict, modular
Lisp
Common Lisp; functional, procedural, reflective, meta; fully parenthesized prefix notation.
nodejs 10.2.1
JavaScript runtime environment using Google's V8 engine
Python 2.7.15
General-Purpose Scripting Language
Python 3.6.5
General-Purpose Scripting Language
PHP 7.2.5
Server-Side Scripting Language (primarily used for the web but also for general-purpose)
Perl 5.26.1
A high-level, general-purpose, interpreted, dynamic programming language
Ruby
A dynamic, reflective, object-oriented, general-purpose programming language
Rust
A systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.
Scala
A general-purpose programming language providing support for functional programming and a strong static type system