I assume you're referring to the ability to read these files from within your browser? I can't answer for eBook and epub files, but you can view PDFs within the web browser. It's not the fastest of processes though. I just recorded the time it took for me to switch through a couple pages in my 119 page PDF and the average load time was 27.3 seconds. I'm using the pink pogoplug btw. Another model may render faster results.