dban - zero your hdd with a live CD

[labbe5]

https://dban.org/

The website provides you with dban, free for home and personal use, as an iso file to download and install on a CD or USB flash drive, then booting your PC with it and proceeds with zero-filling your hard drive, a low-level formatting.

For a certificate of data removal, you need another tool : Blancco Drive Eraser.

Introducing Dban and Blancco Drive Eraser :

While DBAN is free to use, there’s no guarantee of data removal. It cannot detect or erase SSDs and does not provide a certificate of data removal for auditing purposes or regulatory compliance. Hardware support (e.g. no RAID dismantling), customer support and software updates are not available using DBAN. Should you need to erase data from a SSD or require a certificate of data removal, request a free trial of Blancco Drive Eraser.

[DPUP5520]

Hey labbe5 you should check out nwipe, it's a fork of nwipe that started up when development of dban started slowing down and eventually halted in favor of them teaming up with and pushing a commercial shredder. Nwipe has pretty active development and can be compiled inside of puppy and unlike dban can securely wipe SSDs.