L0phtcrack is now open source. It was a commercial password cracker for over 20 years. Here is the history.

https://www.slideshare.net/cwysopal/history-of-l0phtcrack

History of L0phtCrack

The history of one of the most famous Windows password cracker.

@Weld still remember the first time I used this as a test against an NT4 domain. It started with laughing at how quick it worked which then morphed into terror as the results sunk in.