Top Alternatives to NOOK

Calibre is an Ebook management software.

Amazon Kindle is a series of e-readers designed and marketed by Amazon.com.

FBReader is a free ebook reader. Main ebook formats: ePub (including main features of ePub3), Kindle azw3 (mobipocket), fb2(.zip).

Google Play Books (formerly Google eBooks) is an ebook digital distribution service operated by Google. Users can purchase and download ebooks from Google Play, which offers over five million titles, with Google claiming it to be the "largest ebooks collection in the world".

iBooks is an e-book application by Apple Inc. for its iOS and macOS operating systems and devices.

Cool Reader is a configurable eBook viewer.

Aldiko is an e-book reader application for the Android and iOS operating systems.

Scribd is a digital library and e-book and audiobook subscription service that includes one million titles.

Moon+ Reader an ebook reader for mobile devices.

GoodReader is an iOS application used to view documents in different formats, including .doc, .pdf, and .xls.

EPUB is an e-book file format with the extension .epub that can be downloaded and read on devices like smartphones, tablets, computers, or e-readers.

AlReader is a mobile reader app.

ICE Book Reader Professional is an e-book reader. It is also possible to use ICE Book Reader Professional as a teleprompter.

Document Viewer is a highly customizable document viewer for Android.