Does just what is says, which makes it a unique tool. Lets you compare output of apps that you otherwise never could. The comparison shows the deleted and inserted text, side by side, in two different colors, and generates a text version you could copy and paste. Doesn't do things you might expect. Doesn't save the names of the files you compared, so you have to start over to compare again. Doesn't support Recents in the File menu. Doesn't let you select all the generated text at once (just each different paragraph one at a time). Doesn't let you export generated text. Doesn't let you zoom the view. Doesn't have context (right-click) commands. Nonetheless, I'm happy to pay the $20, because it does one good thing.

Accidentally started editing 2 versions of same Pages doc. Pages does not have file diff tool. Export files to PDF and compare with this tool. Merged changes manually using visual results from this app, boom! Done! Save me lot of time for 20 bucks. Five star! The end.Not the end! This app is also good for when you are putting the final touches on a document. You save your last prior version to PDF. The you put in the last few edits into your master file (say, in Pages). But did you mistakenly accidentally add random characters or delete random stuff by mis-typing or your fingers tapping the mouse pad at the wrong time? Well, you can find out by saving your new doc as PDF then diffing it to the prior-to-last good PDF. Wow, good stuff!

This is exactly what I needed to compare the text of two very long PDF documents. I would say however it needs some refinements to be excellent. First, I would like to see an option to show page numbers. Second, I think the text selection in blue is a little messy when scrolling. Also it would be nice if mousing over the center column allows the user to scroll both documents in tandemn without clicking/dragging. Like others, would also like to see an Export option. But this is a great start, and it saved me a lot of time.

I used this app to compare two 115 page PDFs. Big, bold highlights so you can quickly scrub through and see the changes (you can also manually move through each change by clicking a button) Runs very fast, even on my ancient 2015 MBP Option to exclude header & footers so I could ignore page numbers Very accurate, from what I could see--no changes missed, and only a few false positives (which may have been minor formatting differences that looked the same to my eye)The only negative:- No way to export a PDF with all changes highlighted. You can export a RTF or HTML doc, but that's just not the same. I would LOVE this feature to be added.