Readers nowadays are shifting towards ebooks because of how easy and convenient they are to use… The catch is that your device has to support the book format.
Fortunately there are tons of ebook readers out there for any type of device. Personally, I use fbreader because it is very user friendly and you can download plugins to support more formats. Major e-book formats supported are ePub (including main features of ePub3), unencrypted Kindle azw3 (a.k.a. mobipocket), fb2(.zip), RTF, doc (MS Word), HTML and plain text.
FBReader can synchronize your library, reading positions, bookmarks, etc. with the FBReader book network (https://books.fbreader.org/), a Google Drive based cloud service. Alternatively, you can download books on your browser and open them using FBReader.
It has lots of options that allow you to configure reading parameters and app behavior for your preference. It is available for android, iphone, windows and mac, you can get them on their respective appstores.
For android users you can download the latest free version of Fbreader here: FBReader apk download
Download the bookshelf plugin for easy access to your ebooks here: Bookshelf plugin
Download the plugin for pdf support here: PDF plugin.
You can however chose to buy the premium version which costs about $6, as it comes with inbuilt pdf compatibility and a few other perks. you can get it on GOOGLE PLAY STORE.
Iphone users can only download from APPLE STORE. It is also preferable to buy the paid version due to limitations on the free version for now. Hope this was helpful, please drop your comments on how we can improve or on requests you may have. Cheers.