How does CCleaner know what files it can remove?

CCleaner uses a set of programming parameters to work out what files it can and can't delete: 

These programming parameters (or rules) cover everything from Windows temp files, files that have been put in the Recycle Bin, to old virus definition files that can clutter up your hard drive.

CCleaner currently supports over 200 applications.

We make sure CCleaner only removes files you don't need:

We spend a lot of time checking CCleaner's programming to make sure this is the case. 

We also monitor any changes to the apps CCleaner cleans, for example, any new updates or functionality changes to these apps. Put simply, if they change something, so do we. 

You can view the latest cleaning rules by running CCleaner with the /export option.

Find out more about CCleaner's cleaning rules.

Here is an example rule, selected from the software's winapp.ini file.

Example of an entry in the winapp.ini file

Find out more about what each of these entries means.