Likes fixes a glaring problem with Instagram and it's free. The app is designed for iPhone 5 and up and for iOS 7 and up. In Instagram, you cannot save pictures you've liked. I save pictures because they inspire me, amuse me, because I want to later attempt to emulate them to improve my own photography, or because they are pictures of or by my friends and family and I want to remember them. But at any time, anyone can remove their pictures from Instagram and I will lose access to those photographs.
Instagram only keeps track of your most recent likes so you cannot go back in time to see pictures you liked in an earlier time. Likes does one thing and one thing only: It downloads to your camera roll any pictures you want from the list of pictures you have liked.
When you first run Likes, it asks you to authenticate yourself with Instagram. Once that is done, it presents a list of your favorited photos. A single tap downloads the picture to the "Likes" album in your camera roll (which it creates if it is not already there). A long tap and hold loads that picture in Instragram. And that's it! It's probably the simplest app I have ever used.
Pictures that you can download are presented in a grid. Pictures that are in the process of downloading have a red circle that fills in radially (as with iTunes and the App Store). Pictures that are already downloaded have a check mark.
The only problem I found with Likes is that it doesn't remember between sessions what has already been downloaded. The grid is clear as if nothing had been downloaded though all of the pictures I'd already downloaded were still in the "Likes" album in my camera roll. I also would like a feature where it periodically checks in the background for new pictures I have liked and sends a notification event to remind me to download the new liked pictures. Of course, this is easily automated using If This Than That. But for people who are not willing or interested in learning to use a service like IFTTT.com, Likes is an excellent solution.