Komikku - An online/offline manga reader for GNOME developed with the aim of being used on the Librem 5 phone.
YACReader - Download YACReader for your platform. Windows, Linux, MacOSX. And enjoy you comic books cbr cbz with the best comic reader.
Kinoko - Load the online comic content supported by any plug-in project to provide a convenient online comic viewing experience.
Tachiyomi - A free and open source manga reader for Android.
Challenger Comics Viewer - Challenger Comics Viewer is a FREE (NO ADS) advanced comics, manga, books and PDF viewer.
Mcomix - MComix is an user-friendly, customizable image viewer.