In Auth0 you can use the hosted login page as a signup page too. With social login the user just clicks the social network they want to sign in or sign up with and Auth0 takes care of all that. If you want to use a database connection, you can enable a ‘sign up’ tab on Lock to facilitate that. You can even add additional fields and require users to agree to your terms and conditions:
https://auth0.com/docs/libraries/lock/v11/configuration
For social connections, it doens’t request any additional information from the user. However, for each social connection, you can set up what information you’re gonna request from the social network about the user. The social network will then show the user a consent screen and if the user consents, they’re send to your app, along with the requested data. This is the “this app is requesting access to…” screen you see when you log in with for instance Facebook.
You can find docs about each possible social connection here:
If you want to show a screen where the user fills out some info on first login you’ll need to build that logic into your app or use a rule for it. Here’s an example for how to detect that: https://github.com/auth0/rules/blob/master/rules/signup.md
Auth0 can send a verification email, but you’ll have to enable it in your Dashboard. It’s under the Emails tab. If you want to customise your email, use this support article (and keep in mind that email customisation doesn’t work on the free plan):
Auth0 does check for email duplication within a connection (at least I know they do this for database connections, social might be a different story, but I’d be surprised), but not between different connections. What that means is that user@example.com can’t register twice using different Facebook accounts, but they can do so using a Facebook and a Google account. If you want to prevent that, you can use a rule to link the two user accounts. Keep in mind account linking doesn’t work on the free plan.
There are three ways to link accounts: automatic, user initiated and suggested. The docs have all the info you need (and explain it better than I ever could):
I hope this helps! Good luck!