Grids offers a beautiful way to experience Instagram on Mac. The app has a clean, adaptive UI and works at full screen as well as widget-sized window.
The app lets you switch between multiple accounts seamlessly, allowing you to like, comment, follow, search people and tags. The Bookmark feature allows you to bookmark people (without having to follow them), locations, tags and individual photos or videos (without having to like them).
Don't use this app, you will be fired from IG right away. They bann this type of third party application because they think that you are a bot.