Customize your session token
Session tokens are JWTs generated by Clerk on behalf of your instance, and convey an authenticated user session to your backend.
They typically contain a standard set of claims that are required for Clerk to function. However, you can customize them and retrieve the data at any point.
Clerk has default claims that will be included in this session token. You can read about Clerk's session tokens and it's default claims.
How to Customize your session token?
Go to Sessions in the Clerk Dashboard
Firstly you need to go to the Sessions tab in the Clerk Dashboard.

Click the Edit button
Next from the menu select the Edit button.

Add a new claim to the session token
At this point, you are able to select all the session tokens you need. This examples adds a new claim called fullName
and primaryEmail
to the session token.

Using the custom claims in your application
Now that you have added the custom claims to your session token, you can use them in your application. Below is an example of how you can access the custom claims in your application.
Using getAuth
in your Next.js application
import { getAuth } from "@clerk/nextjs/server"; export default async function handler(req, res) { const { sessionClaims } = getAuth(req); const firstName = sessionClaims.fullName; const primaryEmail = sessionClaims.primaryEmail; return res.status(200).json({ firstName, primaryEmail }) }