B-Donor is different .. Your data will not be available to requesters but Donor who will receive notification on his/her mobile for requests of compatible blood group near to his/her saved location. Requester will not know any donor's data. Donor also may go to hospital and donate blood without even a phone call. The app uses your location only once during sign up then send notifications based on location you selected on the map. This means that user can revoke GPS access after sign-up.