I have Bookcrawler on my iPhone, iPad, and iMac (version 1.8.1). I started cataloging my books in the last two days. My objective is to pack away technical and a some other books and get them out of my office. I need Bookcrawler so that I can tell if I even have a book and where it might be: office, box X in garage, … Bookcrawler is quirky but my process works so far. I enter data on the iPhone and export to the iPad and the iMac via Dropbox. I won’t go in the other direction yet until I have all the books, maybe 600, into Bookcrawler. So far I have 119. Some of the books go back to the early 1900s. I have given Bookcrawler five stars rather than four stars to encourage the developer to continue working on this app and the related iOS app. As a footnote, I hope to share some of my Bookcrawler library info, as csv files, with other people that are interested in acquiring technical or scientific books. As another note, I found the ISBN Scanner via iPad Pro unusable. The ISBN Scanner works most of the time on the iPhone 6. I haven’t tried scanning on the iMac.