You can sign up for a free account here - FollowerFilter.com. Unlike its competitors, the free version is quite comprehensive. The only limit is 100 unfollows a day. If you pay them the $2.99/mo you erase that limit plus the ads go away. The ads aren't even intrusive, either.
Unfollow the Dead Weight
Yup, like its competitors, FollowerFilter lets you look through the people you are following who aren't following you back. You can determine if you can stop following some of them. You can sort by their last post date, their number of followers, and more. It doesn't show you the actual last post on the screen like some others do, but it's still quite useful. That information is just a cut-and-paste away. Unfortunately you can't actually just "click" on the account to see their details, for some reason. You have to cut and paste the shown account name into a new browser manually. This is definitely a down-side of this tool.
If there are people you are following who haven't posted in four years, maybe it's time to give up on them. Your ability to follow is not unlimited, after all. You want to follow as many people as you can who are in your genre. That way you build relationships and can retweet important posts that your audience will find useful. It's time to prune off those people who stopped using their account and, instead, follow people who are active.
People Following You that You Aren't Following Back
Then we have the other side of the coin. The people who are following you. Are you not following them back? Why? Is it because they're a spammer? These are the people you should block or unfollow. You don't want to keep them on your lists. We all get the porn and marketing followers linking to us as their way to get new business. Unless you do want to do business with them, close that door.
One option to find healthy accounts to follow back is to sort the list by latest post so you can see who's active. Look at those active people and see if they're a good person to follow or a spammer to block. See those green buttons? Those are people following me who I havenít followed back yet. Those are the accounts for me to look at.
Another choice is to filter by number of followers, to see if there are large accounts you can follow back.
In general, you do want to follow back all legitimate accounts, as part of the TweetKarma.
So, to summarize, FollowerFilter is a solid program with full-featured functionality for free. If you don't mind ads, and you don't need to unfollow more than 100 people a day, this is a great option. You do have to log into each account separately, but if you have multiple accounts you might want to work on one each day and cycle around. That way each one gets some attention regularly and your list grows!
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