The following sites allow execution of some languages from a web browser:

code.worldHaskellEducational programming environment by Google.
easylang.onlineEasyLangIDE, Tutorials.
The Go Play SpaceGoPlayground with Doc-Ref, Turtle- & Nightmode.
The Go PlaygroundGoThe official Golang playground.
Groovy PlaygroundGroovyLoad save via GitHub/Gist.
Groovy web consoleGroovySave and share. Runs on Google Cloud Engine.
Repl.itBasic, C, C++, Java, JavaScript, PHP, Ruby, …
IdeoneBash, C, C++, Go, Haskell, Java, Pascal, Rust, …
Gambas PlaygroundGambasCLI only.
ScalaFiddleScala.jsTranspiler for Scala to JavaScript.
ScastieScastieScala on a JVM. Only supports static input.
TIO> 500 languagesOnly supports static input - no interactivity