Utility Box is a free After Effects Script that contains a variety of tools.
How to install
In After Effects, go to Edit -> Preferences -> General, make sure “Allow Scripts to write Files..” option is checked. Now you can run the script by going to File -> Scripts -> Run script.
Run as dockable panel
To run this script as a dockable panel, you have to place the .jsx file in your After Effects root directory -> Support Files -> Scripts -> Scripts UI Panels