The ebooks of the Amazon Kindle app can be found on your Android phone in PRC format below the folder /data/media/0/Android/data/

Where are Kindle files stored?

In which folder are these books saved? The folder the files are stored in can be changed, so it is possible that someone will have put them into a different place on any given computer. If you can’t locate where the files are, try searching for the files the Kindle uses, which are called MOBI files.

Where are books stored on Android?

If you want to add books you downloaded on your computer, the books are stored in: /data/data/ google account}/volumes , and when you are inside the “volumes” folder you will see some folders with a name that is some code for that book.