My client wanted an app that sends otp to his customers directly from his mobile phone instead of using proivders like BulkSms. This is a flutter app which automatically send OTP to users registered on his website, directly from the device. Both the app and website are synced with firebase realtime database.
Register app to your firebase and save the google-services.json as shown in https://firebase.google.com/docs/flutter/setup?platform=android#create-firebase-project