Here's useful app Kindle drm removal v4.0 release
+ support batch mode, remove all ebooks in folder with 1-click,
+ support azw3,azw4 file now!
Kindle DRM Removal v18.104.22.168-Lz0
Kindle DRM Removal quickly and easily remove kindle drm protection, user can read Kindle ebook on Kobo, Sony Reader, or convert to PDF format without limitation.