A free program for Android, by ITAmazons.

InStalker – IG Profile Tracker is an app that lets you find out who is your secret follower and who is not following you back. The app saves your IG stories and videos in HD format. InStalker allows you to download IG stories and videos with a single click and also allows you to share them directly. You can easily find out who does not follow you back.

The InStalker app gives you the best and easy user interface to get detailed analytical reports of your social media account. You don’t have to worry about anything else because this is completely free.