Where does Chrome stores offline books downloaded using Amazon-Cloud Extension on Windows 7?

I think I've found where it stores them, but you won't like it.

C:\Users\Username\AppData\Local\Google\Chrome\User Data\Default\databases\https_read.amazon.com_0

Contains a couple of files that don't have file extensions. They are SQLite 3 files. If you keep track of the file size and last edited time when you download a book, it gets bigger and is modified at the same time. Having potentially found the book, I still didn't get anywhere. Looking at the database in Sqlite Browser, it seems that the books are broken apart into thousands of fragments.

So this doesn't directly answer your question, but if you're trying to find the .mobi files for use with Calibre, I would just download the Kindle for PC application and find the downloaded files for importing into Calibre.

They're stored in...

• Windows: Libraries/Documents/My Kindle Content
• macOS: ~/Library/Containers/com.amazon.Kindle/Data/Library/Application Support/Kindle/My Kindle Content