I want to know if there's an application or website that can help me know who are the people that are not following me back, I have 3,549 followers but I'm following 3,612. So I'll like to know who are those users that don't follow back, because it's not easy to go to every URL of every username and know if they are following me or not. I've googled it and the things I found are not available for download anymore.
How can I know who's not following me back on Tumblr?
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