Alternatives to determine if a user exists in Auth0

We plan to roll out Auth0 in phases. Due to this, users may encounter scenarios where their account was created by Auth0 Universal Login the first time but when they login the second time, they may come across a version of the app that uses the previous sign up/logic (without Auth0). We would like to handle this so users don’t have a bad experience. In order to this, we need a way to verify if the user has an account already provisioned by Auth0. I thought of using the users-by-email management API. But this API has a rate limit of 500 requests per minute which may not be sufficient for our use case.

Are there any other alternatives to verify if a user exists in Auth0?

Hi @sreeram.jayan

A better way to do this is to create an Auth0 custom DB connection that connects to your legacy login platform. Then both the legacy apps and the migrated-to-Auth0 apps are effectively using the same login credentials and profiles.

Once all your legacy apps are converted, you can then move users into Auth0

John

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Thanks John. I am referring to a single web application here.
Let’s say we have a web application A that uses Auth0 for login/sign up behind a feature flag. In prod we plan to have let’s say 50% of the users use the older authentication mechanism and then the other 50% use Auth0.
User Jane lands on a version of the app that uses Auth0 and signs up. She then logs out and then logs in again. This time she lands on a version that uses the older authentication mechanism. But the older system doesn’t know that she has an account already provisioned.
How do we make sure that users signing up with Auth0 can still log into the app using the older authentication mechanism? Using custom DB connections will still tie the app to Auth0 right?

I guess my question is if it’s possible to do a gradual rollout with Auth0 without impacting every user?

Hi @sreeram.jayan

Yes, it is possible, as I noted above:
Use an Auth0 custom DB connection to pass through to your legacy mechanism.
Once everything is tested, you can migrate the users fully into Auth0.

John