This tool is an open-source standalone visual interface to make using the Windows 10 compact.exe function more available to more people. It only works on Windows 10 as the compact method used is only offered in Windows 10

The compression used by compact.exe is similar to the built-in NTFS compression in that it is transparent. Compressed files and programs can still be accessed as if nothing has changed and show up in Explorer as they normally would — they'll just be decompressed on the fly at runtime. However, the newer algorithms used by Compact are much more efficient.

Reddit thread from the author with a lot of info

I tried this myself. I saved about 440GB in total, 80GB of which was saved on my collection of Emulator Games.

Just wanted to spread the word, as this is an extremely useful feature of Windows, and this tool makes it easier for those not familiar with the command line.

This is a lot different to the option you can enable on a per drive basis to use NTFS file compression, for clarity.

In the large testing on the main thread, and testing myself, it seems to have no impact on performance.

Note: I'm not the author of the tool