Okudum (I Read It) is a free Android book-sharing app by indie developer Dronopter. List books you have finished and request books from other readers; the book itself is free and you only pay cash-on-delivery shipping. Each member starts with 2 points: requesting costs 1 point, sending a book earns 1 point. Google Play: https://play.google.com/store/apps/details?id=com.okudum.app