Create a Custom JWT Auth Server

Learn how to integrate your auth backend with our in-app wallets solution so you can onboard your users into web3 seamlessly.

This guide will show you how to create your own Auth Server that is compatible with the JWT auth strategy. By doing so, you can have full control over user authentication and data security. This allows you to ensure that your application meets specific compliance requirements while also providing a customized sign-in experience.

  • Setup

    • Create a new directory for your project and navigate to it in your CLI

      mkdir jwt-auth-server
      cd jwt-auth-server
    • Initialize a new Node.js application

      npm init -y
      yarn init -y
    • Install the necessary packages

      npm install express jsonwebtoken
  • Generate RSA Key Pair

    • To generate a private and a public key run

      ssh-keygen -t rsa -b 2048 -m PEM -f keys/rsa.key
    • To create the output file run

      openssl rsa -in keys/rsa.key -pubout -outform PEM -out keys/
  • Convert Public Key to JSON Web Key Set (JWKS)

    • Display the public key:

      cat keys/
    • Copy the displayed public key.

    • Convert your public key to a JWK using an online JWK Creator tool. We recommend using JWK Creator by Russel Davies.

      • Paste the public key, set Key ID as 0 (arbitrary string, must match when signing JWT), and then note down the generated JWK.
    • Create a jwks.json in the project root and place the generated JWK in a keys array.

      "keys": [
      ... JWK ...
  • Create the Server

    • In the jw-auth-server directory, create a file at the root named server.js and paste the following:

      const express = require("express");
      const fs = require("fs");
      const jwt = require("jsonwebtoken");
      const app = express();
      const PORT = process.env.PORT || 3000;
      const PRIVATE_KEY = fs.readFileSync("./keys/rsa.key", "utf8");
      const jwks = require("./jwks.json");
      const users = [
      { id: 1, email: "[email protected]", password: "password123" },
      app.use(express.json());"/login", (req, res) => {
      const { email, password } = req.body;
      const user = users.find(
      (u) => === email && u.password === password,
      if (!user)
      return res.status(401).send({ message: "Invalid credentials" });
      const payload = {
      iss: "",
      aud: "EpicGame",
      exp: Math.floor( / 1000) + 3600,
      const token = jwt.sign(payload, PRIVATE_KEY, {
      algorithm: "RS256",
      keyid: "0",
      res.send({ token });
      app.get("/.well-known/jwks.json", (req, res) => {
      app.listen(PORT, () => {
      console.log(`Server started on port ${PORT}`);
    • Replace with the actual domain for the application.

  • Test Locally

    • Start the server:

      node server.js
    • Test login:

      curl -X POST http://localhost:3000/login -H "Content-Type: application/json" -d '{"email": "[email protected]", "password": "password123"}'
    • Test JWKS:

      curl http://localhost:3000/.well-known/jwks.json
  • Deploy

    To deploy the server, you can use services such as Zeet or Docker.

    Once deployed, replace http://localhost:3000 in the JWT payload with your actual domain

  • Integrate In-App Wallets

    • Navigate to Wallets > In-App Wallets in the thirdweb dashboard.

    • Create a thirdweb API key if you don't have one or select an existing key to use for this project. Learn more about API keys.

    • Allowlist domain or bundle IDs in Access Restrictions.

    • Navigate to the Configuration view and enable Custom JSON Web Token

    • Set the JWKS URI to your-domain/.well-known/jwks.json

    • Set the AUD to EpicGame or the value you set as the aud in the server.js file.

    • Copy the client ID.

    • In your preferred thirdweb client SDK, pass the JWT you retrieved from logging in to the server.

A persistent, cross-platform wallet is now created for your user.