This Library tops our list for simply being an 'Open' one. It basically means that anyone's allowed to publish their work here (as long as it's informative and worth the read). Their ultimate goal is to make all the published works of people (in all domains) available to everyone in the world. So you get to read the best of books, and if you're a writer too, this one's a great platform to publish your work. The best part is that you can even sponsor a book to someone through the website.
Open Library
