Is "nameidentifier" Claim a Unique Identifier?

(First post so not sure I got the tags right.)

I am using openId scope (only) and it only returns two claims: “sid” and “nameidentifier” (

Is nameidentifier a stand-in for a unique Id? Is it reliably unique? Will I also get the same field (with different value) on a login using another social provider or Auth0 login/password?

I can’t find a reference explaining this (and other) claims, and all the posts I find seem to recommend using claims called “sub” or “user_id” for uniqueId–I’m not getting either from Auth0.

Using .Net 8, free Auth0 account for now (if it matters).