Another option is Auth0 (free for basic use, low cost for some other features depending on your needs.
Authentication methods for nginx As others have said, Cognito is an option with Amazon.
Auth0 takes out the pain of developing a full authentication system from scratch for your application and managing user credentials by yourself.
Auth0 Provider and Strapi Tutorial Auth0 is an adaptable authentication and authorization platform.
What kind of auth implementations have you seen throughout your careers? There's lots of great auth services nowadays, like AWS Cognito and Auth0 if you have a specific use case and need to spend time on the nitty-gritty details, or Userfront and similar services if you want standard auth that works out of the box.