"Case sensitive" means that it matters whether you keep characters matching the same case. So, let's imagine a hypothetical service: # This should work for

"Case sensitive" means that it matters whether you keep characters matching the same case. So, let's imagine a hypothetical service: # This should work for any such service: Service.set_password('MyPassword') Service.verify('MyPassword') Logging in with the mixed-case password (which should, of course, work) does not tell us anything about whether it's case sensitive. However, if alternate-case verisons of your passwords work, your service has case insensitive password: # These fail if a case-sensitive service Service.verify('mypassword') Service.verify('MYPASSWORD') If we can give it either too many or too few characters, then they are likely truncating your password before storing/testing it: # They drop characters if these work: Service.verify('My') Service.verify('MyVoice') Edit: And, in case they are trying to be nice and allow you to log in with your phone, they might do something lame like store your password as the numbers-you-would-type, rather than the actual characters, in which case this might work: # I hope not: 'mypassword' phone pad digits Service.verify(6972779673) # Even worse, if they might store only the first digits: Service.verify(6972) Apologies if I've made any typos, but I hope that clarifies how one might verify that passwords are treated as case sensitive or not.