Calibre is an open-source e-book library management application that enables you to manage your e-book collection, convert e-books between different formats, synchronize with popular e-book reader devices, and read your e-books with the included viewer.

Download: Portable | Windows 64-bit

Releases
View: Calibre Home Page

https://download.calibre-ebook.com/4.23.0/

Release v10.0.9 (RC1 for 10.1.0) · noDRM/DeDRM_tools · GitHub

https://github.com/apprenticeharper/DeDRM_tools/releases/download/v7.2.1/DeDRM_tools_7.2.1.zip (works with calibre 6.6.1)