Online-IDEs / -Compilers / -Interpreters are websites where you can enter/paste some sourcecode, and have it executed.
They commonly offer the functionality to give the user a short URL for the entered code, like http://pastebin.com/ .
Smallish programs can be run that way, typically no more than a few kb of code. Same for input-data.
Some Online-IDEs are dedicated to only one language:
These Online-IDEs have support for tcl:
Some others are listed at Tcl Web Resources .. these pages might benefit from being merged.