Twitter USERNAME to ID mass converter?

Hey guys, I was just wondering do you know any good twitter username to id mass converter, the issue is that I have a huge list of twitter usernames that I am trying to unfollow from my accounts, but the software i am using requires that for the unfollower to work i need the IDs, not usernames, is there is any good software for that? Also, if not, are there any UNFOLLOWERS that can accept usernames?

Thank you.

Or what is the best way to go about it?

tweet adder 4 does it.