Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
Archive.org - Internet Archive is a non-profit digital library offering free universal access to books, movies...
Project Gutenberg - Project Gutenberg offers free ebooks to download.
ManyBooks.net - Thousands of free ebooks, pre-formatted for reading on your computer, smartphone, iPod, or e-reading device - ePUB, Kindle, eReader, PDF, Plucker, iSilo, Doc, RTF, Mobipocket, Newton Paperback, and zTXT ebooks ready to go!
Apple Books - The all-new Apple Books has been redesigned to make finding, reading, and listening to books a beautiful, effortless experience on iPhone and iPad.
Open Culture - Discover thousands of free online courses, audio books, movies, textbooks, eBooks, language lessons, and more.