Eraser

Unique opensource project. Make sure select appropriate algorithm, by default it's 7 pass algo which will take a lot of time.

BEWARE! Destroyed my partition table, received blue screen of death trying to erase a partition on a separate drive from where my system partition is. I was very careful in selecting the correct partition. Yet instead of erasing the partition it messed up my partition tables preventing me from booting. I received an immediate BSOD upon executing the command. My system drive is an NVMe so perhaps this tool does not support that.

Decent program that does the job with minimal fuss. It did randomly quit the other day in the middle of a job, which I luckily checked on it and noticed, though I'm not sure if that was Eraser's or Windows' fault. As some others have mentioned (complained about), it does take a long time, but that's just the nature of what it's doing, and all programs are going to be slow; if they're not, they're not doing a good job. I tried several others, and they ranged from horrible to ok. Of them, one or two would probably be suitable replacements for this one if it were to stop working, but I would say Eraser is probably the best interface and it's free, portable, and can do files, free space, and entire drives. The only thing I don't like about it is the lack of parallelization, i.e. being able to wipe multiple drives simultaneously. I see no good reason why that shouldn't be possible, and searching the forums it seemed the dev intended to add it in v6, but that was years ago and it's now on v6.2. I signed up on the forum to inquire about it, but then couldn't post, so that was a massive waste of time. To the devs, in case you read this: don't use a forum for support then not let people post in it (shouldn't need to be said, but there it is). To anyone looking to do multiple drives that happens to read this: as I said, I tried several programs, and none of them will do it except one, which you have to buy. What I ended up doing is setting up a VM with DBAN and assigning the drives I wanted to wipe to the VM. DBAN wipes multiple drives in parallel, but doing it in a VM allows for the computer to continue being used instead of being tied up for days, and it also ensures DBAN can only see the drives you want to wipe, so it helps prevent mistakes.

It takes many, many hours to delete the unused space on a 500GB drive. If your drive is 1TB or larger and your time is worth anything, it will be faster and cheaper to copy the files to be kept to a new drive and destroy the old drive. Contrary to the information given here, the forum is useless for support. You will be forced to create a 10-character password for the forum account -- does the admin think we only have one forum account or that we should be forced to store and retrieve thousands of passwords for sites that don't have any sensitive information? -- only to find that "you have insufficient privileges to post" a question, so there is no support there. And all of the links in the FAQ topics I was interested in (erasing free space) are broken.