The Portable Freeware Collection Forums

Can anyone recommend a program to erase free space on a disk?

I have some old computers I want to fix up for folks, but I need to wipe the free space on them; I don't want to wipe the entire drive (with its OS) - just the unused space so nobody can ever dig them up again.

I've looked at this, but its not portable. Besides that, it is old, and funky and requires payment for "advanced" features.
Disk Redactor

I'm trying out WipeDisk - but it is also quite old. I've got it running right now, and I think it's doing something, just not sure.

Check out Free File Shredder, which has a "Shred Free Diskspace" function.

You can extract using Universal Extractor and run.

It's not stealth, writes settings to registry. But I don't think it's an issue for this program given the small number of non-critical options.

First, please make sure you're wiping a magnetic disk, not any SSD drives. I know most older computers that's understood, but I've met a few machines that fooled me. Running a file wipe on these drives can drastically shorten their life

I'd probably go with Eraser https://www.portablefreeware.com/index.php?id=267 - it has a drive wipe that includes a few extras ... just one pass should be fine but keep it to a maximum of 3 passes on the drive and use the one pictured below. Anything more is wasteful.