As someone who's always on the lookout for free reading apps, I've found several great options for offline reading. One of my favorites is 'Libby' by OverDrive, which lets you borrow e-books and audiobooks from your local library for free. You just need a library card, and you can download books to read offline anytime.
Another fantastic app is 'Project Gutenberg', a treasure trove of over 60,000 free e-books, mostly classics that are in the public domain. It's perfect if you love timeless literature like 'Pride and Prejudice' or 'Moby Dick'. For more contemporary reads, Scribd offers a free trial with access to a vast library, though it's subscription-based after the trial. Lastly, 'Google Play Books' has a section for free books that you can download and read offline. These apps have been lifesavers for me during long trips or when I just want to curl up with a good book without spending a dime.