Coding Ground is an amazingly comprehensive set of free online terminals and IDEs for about 100 different computing languages. The list includes Unix languages (bash, ksh, awk), cross-platform languages (Ruby, Python, Perl, Java, etc.), web languages (coffeescript, Go, Dart, jQuery) MS Windows-specific languages, markup languages (CSS3, HTML, Markdown), and even a bunch of esoteric languages (Malbolge, LOLCODE, Brainf**k, and Whitespace). These (appear to) run in fully sandboxed Docker-based containers.
Graph your life at MIT's Mycrocosm. Simple interface. Interesting potential. Worrying about. Freelance: No Idea What the Hell Is Going On. Food and Liquid Consumption. Also allows for sharing datasets with other users.