https://publisherrocket.com/

Do I use it? Yes - I have found this tool extremely handy for choosing keywords, using the reverse ASIN search, selecting the best categories, and using the competition analyzer.

Price: $199 lifetime with updates

Publisher Rocket is a tool from Dave Chesson at Kindlepreneur. He’s got a bunch of great tools and is accessible for support and comments. When choosing how to position a book on KDP, it is handy to have assistance in selecting the keywords and the categories.