If you have published books on Amazon's Kindle platform, you'll like this free* tool I think. It takes a couple of seconds to install, by dragging the bookmarklet to your browser's bookmarks bar.
Then log in to your KDP dashboard, and Book Report will tell you how each of your books are doing. You can organise the data by pen name or book title.
Here's the link: Book Report.
* Book Report is free if you earn less than $1000 a month from your Kindle sales, otherwise it's $10 a month. There's a free two-week trial.
I heard about Book Report from Joel Friedlander's newsletter, Publishing 101 Digest.