Having developed arthritis in my hands, I've found that it is much easier for me to read e-books on my Kindle Fire. But you don't need a Kindle to read free Amazon books on your phone, tablet or computer. You can download the Amazon Kindle app here -http://www.amazon.com/gp/feature.html/ref=sa_menu_karl/178-1420621-0855060?ie=UTF8&docId=1000493771
Free e-books are available from a number of apps, including Kindle Buffet which offers free and discount e-books, including popular titles (website http://www.weberbooks.com/kindle/), and websites like www.feedbooks.com/books (classics and new authors).
Free audio books are available at https://scribl.com/info/podiobooks-now-scribl
As with most websites, be aware that there are a lot of ads mixed in with the other material on these sites, so be sure to looks closely before clicking.