FakeFollowers is a free web based Twitter tool that can help you identify which of your Twitter followers are fake, and then block them. This becomes very handy nowadays, as there are so many fake Twitter accounts nowadays, and they add themselves as your followers. FakeFollowers clearly identifies them for you.
To use FakeFollowers, just give it your Twitter username. You do not need to even provide your Twitter password. FakeFollowers will analyze all your followers based on the criteria that FakeFollowers has defined, and then show the ones that it thinks are fake Twitter followers. With each such fake follower, FakeFollowers clearly mentions why it thinks they are fake. This ensures that you can review the criteria defined by FakeFollowers.
If you have a lot of followers, FakeFollowers will take some time to analyze all the followers. It took around 15-20 minutes to analyze all my followers (around 1500). This is definitely a lot of time, but I didn’t mind this a lot, as FakeFollowers was working on its own and not hampering with my work. And the results were totally worth it.