Websta.me a.k.a. Webstagram is a web viewer for instagram and probably the best one. It's been around since 2011. Websta help Instagram users to access accounts, Organize posts into boards, Share/Repost, Get statistics for the account, Send messages to other Instagram users, Subscribe to users and lot more and all this on a personal computer. You can view pictures of the people you follow, Like and Comment on pictures, follow and unfollow users, see your followers, and search & browse popular photos/tags/users. So, basically the features that Instagram has not made available on its web platform.
Websta.me uses Instagram's API to display photos and videos from an account, since API is public; developers/3rd-party websites can use it to get data (that Instagram user have agreed to make public) in order to provide various services to the users. Websta.me doesn't store data in its system, nor it can modify or permanently remove it. To have an account on websta.me you don't need to sign-up/create any account with them, you can simply log-in using your Instagram account and that's all, you'd be able to see your photo stream and various statistics. If you don't have an Instagram account, please create one on iPhone/iPad/Android first because you cannot create an account using any third party service.