The main features of ApolloBot are:

1. Showing the people not following you back.
2. Showing who has unfollowed you since your last check.
3. Global queue search.
4. Showing who has viewed any of your last active stories. Combined with the search functionality you can easily know if a specific person has watched your story. Keep in mind that at time of writing this there is bug on Instagram's part and this functionality does not work. The extension will be updated ASAP when Instagram fixes this.
5. Removing specific people from the queue you don't want to unfollow even if they don't follow you back.
6. Saving and loading queues in order to be processed later.
7. Batch unfollow functionality.
8. Basic and advanced settings allowing you to configure the timeouts, timeout randomization and even the queue hashes in case Instagram changes their APIs.

To use the extension just open Instagram and a new icon will appear on the top right corner. Go to your profile page and click the refresh icon.

Enjoy!