Amazon Cognito vs Firebase Authentication: What are the differences?
Developers describe Amazon Cognito as "Securely manage and synchronize app data for your users across their mobile devices". You can create unique identities for your users through a number of public login providers (Amazon, Facebook, and Google) and also support unauthenticated guests. You can save app data locally on users’ devices allowing your applications to work even when the devices are offline. On the other hand, Firebase Authentication is detailed as "An App Authentication System In A Few Lines Of Code". It provides backend services, easy-to-use SDKs, and ready-made UI libraries to authenticate users to your app. It supports authentication using passwords, phone numbers, popular federated identity providers like Google,.
Amazon Cognito and Firebase Authentication belong to "User Management and Authentication" category of the tech stack.
I started our team on Amazon Cognito because I was a Solutions Architect at AWS and found it really easy to follow the tutorials and get a basic app up and running with it.
When our team started working with it, they very quickly became frustrated because of the poor documentation. After 4 days of trying to get all the basic passwordless auth working, our lead engineer made the decision to abandon it and try Auth0... and managed to get everything implemented in 4 hours.
The consensus was that Cognito just isn't mature enough or well-documented, and that the implementation does not cater for real world use cases the way that it should. I believe Amplify has made some of this simpler, but I would still recommend Auth0 as it's been bulletproof for us, and is a sensible price.