Google Sign-in is a free service . To use Google sign-in you have to use Google’s Firebase authentication service. Pricing for Firebase has three tiers, you can see the pricing at this link https://firebase.google.com/pricing/.
Read moreHow do I add Google sign to my website?
Integrating Google Sign-In into your web app
Read moreHow do I use Google Firebase?
Getting started with Firebase
Read moreHow do I add firebase authentication to my flutter app?
Implementing Firebase Authentication in a Flutter app
Read moreHow do you use phone authentication on flutter?
Enable Phone Authentication in Firebase All you have to do is click enabled. Then download the google-services. json file again, and add it the project under android/app . Note: If you want to authenticate using email/password then check this tutorial: Using Firebase Auth In Flutter.
Read moreWhat is phone number authentication?
Phone number authentication is an authentication method in which a sender sends an SMS message to a receiver’s phone . Then, the receiver logs into its phone with a one-time code provided in the SMS message.
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