Use Kindle Cloud Reader if you don't want to download the Kindle app. Download Amazon Kindle from the App Store, and then open the app and log in to your Amazon account.

The Amazon Cloud Reader features both online and offline modes, synchronizes users notes, bookmarks, and libraries no matter where users have been using Kindle content, and—of course—features ...

All you need is Amazon’s Kindle app and a few taps to start reading; no extra device required ...