https://liberapay.com/ can now check your password and warn you if it appears in Troy Hunt's database of 500 million leaked passwords (see https://www.troyhunt.com/ive-just-launched-pwned-passwords-version-2/ for details on this database).
This is done automatically when you change your password, or when you log in with your password and it hasn't been checked in the last 6 months.
