Suppose you're writing an HTML page about Javascript. You have examples you want to refer to. So, paste the code into the big open box and press the button. You will be shown what the HTML table version of your code looks like. Right below that is a single long line of HTML you can copy. Paste it into your HTML document and you'll have a neatly displayed table, with numbers for all the lines that are non-blank.
Plus, there'll be a button that lets your readers show or hide the numbers so that they can more easily copy the code you're displaying
It converts all sets of four spaces into tabs.
This a total hack job by a non-professional. Please enjoy.