LDiff compares two documents in the browser. You can upload two files to compare using the buttons on the right of the navbar, at the top of the page, or simply drag and drop a file from your desktop onto each button. To copy and paste text to compare, click on the 'edit' icon next to the document name.
LDiff works for both structured and unstructured text. The 'Structured Compare' tab is best for viewing comparisons of xml or html documents; the 'Text Compare' is best for plain text documents. The default styling, and the initial example, is for a U.S. House bill.
For more details see the README file.