PhotoDesk lets you view, like, comment, and download Instagram pictures/videos. (NO Uploads! / Image Posting! Instagram forbids that! AND you need an existing Instagram account). But you can do so much more.
Of all Mac clients, Photodesk allows you to use the most features of Instagram on your Mac and even exceeds Instagram’s functionality:
See pictures on a map
Search for places
Save images / videos
Fantastic, modern UI, optimized for OS X 10.10 Yosemite and OS X 10.11 El Capitan