ophcrack!

John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. Besides several crypt(3) password hash types most commonly found on various Unix systems, supported out of the box are Windows LM hashes, plus lots of other hashes and ciphers in the community-enhanced version.

Windows stores its user information, including crypted versions of the passwords, in a file called 'sam', usually found in \windows\system32\config. This file is a part of the registry, in a binary format previously undocumented, and not easily accessible. But thanks to a German(?) named B.D, I've now made a program that understands the registry.This site provides CD and floppy images for end users to easily edit their forgotten passwords. But it also provides full source code and binary builds of the tools to allow others to use as they like for other purposes. Registry format documentation also available. »

Trinity Rescue Kit or TRK is a free live Linux distribution that aims specifically at recovery and repair operations on Windows machines, but is equally usable for Linux recovery issues. Since version 3.4 it has an easy to use scrollable text menu that allows anyone who masters a keyboard and some English to perform maintenance and repair on a computer, ranging from password resetting over disk cleanup to virus scanning.

Kon-Boot is an application which will silently bypass the authentication process of Windows based operating systems. Without overwriting your old password! In other words you can login to your Windows profile without knowing your password. Easy to use and excellent for tech repairs, data recovery and security audits. Fast, tiny and gets your job done!

GoCrack provides APIs to manage password cracking tasks across supported cracking engines.