Checkmypasswordcomau -

Credential stuffing is an automated attack where stolen username/password pairs from one breach are used to attempt logins on other unrelated websites. By checking a password, users can determine if their credentials are part of the "stuffing" inventory used by cybercriminals. If a password is flagged, the user is immediately notified that the password is unsafe for use on any platform.

Panic ensued. The Australian Cyber Security Centre (which was basically just two guys and a very fast dial-up connection at the time) launched an inquiry. They knocked on the door of the kebab shop office only to find Arthur wearing a tinfoil hat, weeping over a spreadsheet of 14,000 unique passwords. checkmypasswordcomau