When comparing Cool Reader vs Sumatra PDF, the Slant community recommends Sumatra PDF for most people. In the question“What are the best EPUB readers?” Sumatra PDF is ranked 4th while Cool Reader is ranked 5th. The most important reason people chose Sumatra PDF is:
Including PDF, XPS, DjVu, CHM, EPUB, Mobi, FictionBook, PalmDoc, and comic books.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free and open source
Cool Reader is available completely free and is also open source.
Pro Fully customizable
Pro A wide range of formats supported
Cool Reader supports epub (non-DRM), fb2, doc, txt, rtf, html, chm, tcr, pdb, prc, mobi (non-DRM) and pml formats.
Pro Reads many file types
Including PDF, XPS, DjVu, CHM, EPUB, Mobi, FictionBook, PalmDoc, and comic books.
Pro Book updates on the fly
If Book font, style is changed, Sumatra will take the update instantly, No need to close first and import again! Huge time saver for self publishing.
Pro Portable
The application consists of a single file that can be run without installation. You can put it on an external device, such as an usb thumb stick and run it on any Windows machine from the thumb stick.
Pro Multilingual
It's available in 69 languages.
Pro Free and open source
Sumatra is available for free, licensed under GPL with source code available on GitHub.
Cons
Con Constantly changes brightness
Con Could have a better UI design
Con Does not support DRM .epubs
.epubs with DRM are not supported by Cool Reader.
Con Windows only
No Linux or OSX versions available.