BleachBit (www.bleachbit.org) is a free and open-source disk cleaner for Linux distributions, MacOS and MS Windows. Open source helps with transparency as anyone can inspect the code. Bleachbit does not include a registry cleaner. However, there are plenty of free registry cleaners available, should you want to use one.
I use the Linux build of BleachBit, but there are severable reviews of the MS Windows build on the web. Martin reviewed BleachBit in february this year.