With access to over 3,000,000 books and audiobooks, the Kindle app is a no-brainer for reading.
It works on and syncs across Android, iOS, the desktop, and, of course, your Kindle, so your reading progress is up to date wherever you go.
The formatting options, built-in dictionary, and search capabilities are great, but the real killer feature is Amazon’s Whispersync For Voice technology, which lets you go back and forth between reading text and listening to an audiobook. For now, the feature is available on 60,000 titles.
Price: Free (iOS, Android)