Instagram Unfollower Tracker
See who unfollowed you on Instagram. It is free forever, never asks for your password and has no follower limit.
Most unfollower apps require a sign-up or your Instagram password, limit you to 500 followers, and then charge a monthly fee, all while storing your data on their servers.
Follower Tracker is a browser extension for Chrome, Firefox, and Safari. It uses the Instagram account you're already logged into, so there's no login screen and no password required. Just click "Scan now" to see who unfollowed you since your last check, who isn't following you back, your mutuals, and your new followers. It saves every scan so you can track how your followers change over months. You can also search, sort, export lists to spreadsheets, and track several accounts separately. A speed setting is included to keep scans within Instagram's rate limits.
It has no servers, no analytics, and no tracking. Your lists stay in your browser, can be deleted with a single button, and the code is open source so anyone can check it.