If you don't like users who follows you and you follow them back, but then they unfollow you.
With Unfollowers & Insight for Instagram, you can find who unfollowed you on Instagram, who is not following you back, track new followers, and more...
You can not only track non followers but also unfollow a single users , unfollow multiple users or all users at a time.
Discover your insta followers, unfollowers,mutual friends and instagram ghost followers.
Find out “who follows me on instagram”, “who unfollowed me on instagram”, delete instagram followers and just unfollow all non followers on instagram.
With Unfollowers and Insight for Instagram app, you can easily manage and track multiple accounts to discover things you didn't know before.
FEATURES:
✔ Fastest Unfollower app on the store
✔ Track Instagram unfollowers (users who followed you and decided to not follow you anymore)
✔ Track Instagram followers that don't follow you back and fans
✔ Unlimited follows/unfollows
✔ Add unlimited accounts and switch from one to the other in one click
✔ Know your mutual friends

Official web api used.
You should not to make too many requests in short time due to limits. Sorry about that.