EPUBReader Firefox add-on by @epubread is great for e-book reading and an essential part of an author’s testing workflow.
Since its a Firefox extension it will work great across PCs and Macs. Here’s how to get started with EPUBReader today:
1. Use the Firefox web browser to visit this website: http://www.epubread.com/en/
2. Click on the large green button that reads, “Add to Firefox” and follow the instructions through 2 or 3 more clicks.
3. Restart FIrefox
4. In Firefox, choose File Open… and open the ePub file you’d like to read.
The reading experience is a little different on every device, but this is a good way to get a sense of how the ePub will look across devices in general.