https://addons.mozilla.org/en-US/firefox/addon/modcompare/

Hi hn! I needed to compare a lot of pages for a website (same content, spot differences between prod & local dev server), and I built this small add-on to help me.

The main feature of this small project is that it synchronize the 2 windows you choose (scroll, clicks, even some keyboard shortcuts like ctrl and +), but the add-on also show the page size (sorted by file type), and have a few more features that I let you discover.

Let me know what you think of it :)