"Online code execution" is commonly implemented as a webpage
with a text-area for writing/pasting code,
a button "Submit/Execute",
and an output-page to show the result.
That means, usually no graphics or GUI.
Online-code-execution allows for a quick test of (short) programs/scripts, without the need to install something on the own machine.
This are some known websites that allow online code execution:
- Lua-demo : just Lua, with some canned demo-programs.
- CodePad.org : C C++ D Haskell Lua OCaml PHP Perl Python Ruby Scheme Tcl
This can also be used to share/discuss code, much like PasteBin.com.
- Go and Go-playground : can run only Go-programs, with some canned demo-programs.
- ideone.com : Online-Compiler
- tutorialspoint.com / codingground
- CompileOnline.com : lots of programming-languages, as well as shells, text-formatting, file-compare, etc. // renamed to Coding Ground