This application scans all the (non-packaged) Apex Classes in your Org to builds a table of where each property, variable and method is used. Useful for cleaning up unused code.
Only Apex Class metadata is captured from your Org. This data is stored within the app for 24 hours and then completely wiped. If you are sensitive about sharing your Org metadata with this app, I suggest you either don't use it, or run a local version by downloading the source code.