If you are digging through old software or running a legacy system (Windows XP/7, old Linux distro), you might stumble upon . Released back in 2011, this version is ancient by today’s standards (the current version is 7.x), but it still functions as a decent CBR reader .
Retro Review: Using Calibre 0.8.2 as a CBR/CBZ Comic Reader Calibre 0.8.2 CBR Reader