Popular

Python: A dynamic language emphasizing readability.

Node.js: Evented I/O for V8 JavaScript.

C: Low-level and cross-platform imperative language.

Java: A concurrent, class-based, statically typed object-oriented language.

C++: A general purpose system programming language.

Ruby: A natural dynamic object-oriented language.

HTML, CSS, JS: The languages that make up the web.

Scheme: An elegant dynamic dialect of Lisp.

Go: Statically typed yet expressive language with a focus on concurrency.

Rust: A fast and safe systems programming language.

Practical

Clojure: A modern JVM-based Lisp dialect with a focus on immutability

Haskell: An advanced, purely functional programming language

Kotlin: Statically typed programming language interoperable with Java and Android

Scheme: An elegant dynamic dialect of Lisp.

Lua: A lightweight multi-paradigm scripting language.

Python 2.7: A dynamic language emphasizing readability.

Ruby: A natural dynamic object-oriented language.

Python: A dynamic language emphasizing readability.

Node.js: Evented I/O for V8 JavaScript.

Deno (beta): A secure runtime for JavaScript and TypeScript

Go: Statically typed yet expressive language with a focus on concurrency.

C++: A general purpose system programming language.

C: Low-level and cross-platform imperative language.

C#: A Microsoft .NET programming language.

F#: A Microsoft .NET functional programming language.

Rust: A fast and safe systems programming language.

Swift: A modern general-purpose programming language from Apple.

R: A programming language and environment for statistical computing and graphics

Bash: The classic Unix shell

Crystal: Fast as C, slick as Ruby

Julia: A language for high-performance numerical analysis and computational science.

Elixir: A functional, concurrent, general-purpose programming language that runs on the Erlang VM

Nim: An imperative, multi-paradigm, compiled programming language

Dart: A general-purpose programming language used to build web, server, desktop, and mobile applications.

Reason Node.js: Reason compiling to Node.js (via BuckleScript)

Tcl: A high-level language designed with the goal of being very simple but powerful

Erlang: A general-purpose, concurrent, functional programming language

TypeScript: A typed superset of JavaScript.

Emacs Lisp (Elisp): Scripting language for the extensible text editor.

SQLite: Embedded SQL database engine.

Java: A concurrent, class-based, statically typed object-oriented language.

PHP CLI: A popular general-purpose scripting language.

Raku: A highly capable, feature-rich programming language made for at least the next hundred years.

Scala (beta): Scala combines object-oriented and functional programming in one concise, high-level language

Web

JavaScript: The de facto language of the Web.

CoffeeScript: Unfancy JavaScript.

Roy: Small functional language that compiles to JavaScript.

HTML, CSS, JS: The languages that make up the web.

PHP Web Server: A popular general-purpose scripting language.

Game Development

Pygame: A cross-platform python graphics library

Love2D: A free, open-source Lua framework for 2D games

Pyxel: A retro game engine for Python

GUI Development

Tkinter: Python's standard GUI tooklit

Java Swing: A Java GUI widget toolkit

Classic

QBasic: Structured programming for beginners.

Forth: An interactive stack-oriented language.

APL: An array-oriented language using funny characters.

Basic (beta): A fun and simple programming language for beginners

Esoteric

LOLCODE: The basic language of lolcats.

BrainF: A pure Turing machine controller.

Emoticon: Programming with an extra dose of smile.

Bloop: Nothing but bounded loops.

Unlambda: Functional purity given form.