Looking for twitter unfollow tool.

Hy Guys: I have two twitter accounts. I regularly follow approximately 500 to 1000 people but some time twitter worn me about limit. I also face difficulties to unfollow lot of people who don't follow me. Is there any free unfollow tool and what is the exact twitter following limit on the daily bases. Anyone who know that please inform me I will be thankful.
Thanks

Just use a chrome add on. There are plenty for twitter that work great for simple unfollowing. You can set it to only unfollow people who do not follow you either.