Update 2018-02-17: The title of this article has changed reflecting new information I have received since publishing. For mor information, I refer to the last paragraph.
A treasure trove of leaked passwords The API of pwnedpasswords.com is quite remarkable. It not only allows you to fetch the results generally obtained by typing in your e-mail into the browser interface and finding out whether or not you've been pwned from the comfort of your shell.
