How best to validate a JWT from Auth0

Question

I'm currently having users login to my site using Auth0's redirect functionality. It's great, but my past experince with google's oAuth tells me there's a problem. With my other site, we do the same login, the user gets a JWT and posts that to my API server. My API server then takes that token and contacts google to ensure this is actually a token that they made. And THEN, I give them a Bearer code that they can use for when they want to access the database.

With Auth0, I can't seem to find any way to contact them from my API server and say, "Hey, someone sent me this token, it checks out that it isn't corrupted, is for a data that is in the future and it says you are the issuer and it has the proper Auth0 client id. So, did you issue this?"

I must be missing something.

Thanks everyone.