New Google Identity in Nuxt 3

New Google Identity installation for Nuxt 3 with credentials verification in fastify.

New Google Identity in Nuxt 3

I was scared today because two great libraries did not work with Google Sign In for Nuxt 3. I mean auth.nuxtjs and nuxt-vue3-google-signin.

From stack overflow

How to use nuxtjs/auth-next module with Nuxt3?
Just trying to add authentication to my NuxtJs 3 app folloging nuxt/auth configuration docs, but still get an error during app start: // nuxt.config.js export default defineNuxtConfig({ auth...

I learned that first one is incompatible with nuxt 3, but it is planned on roadmap

Roadmap · Nuxt
Nuxt is constantly evolving, with new features and modules being added all the time.

Second simply could not work giving error that was suggesting that something is wrong with my client id.

I checked official Google Docs and see this:

Integrating Google Sign-In into your web app | Authentication | Google Developers

Looks terrible, but hepilly I integrated google sign in button quite fast without external libs. In this article I will show how to implement new Google Identity with Nuxt 3.

Google Identity - how it is different

Because image is worth more than thousand of words, new login button contains avatar:

Sign in with Google button UX | Authentication | Google Developers

Sign In button HTML

To add it to your component you will need paste below html

  <div id="g_id_onload"

  <div class="g_id_signin"

or prepare your own in configurator

Generate HTML code | Authentication | Google Developers

There are three elements that we have to connect:

  1. config.public.googleClientId - google client ID
  2. googleLoginCallback - globally defined function that will get results of login
  3. google library that will make these buttons working

Passing .env to Nuxt 3

To pass .env to nuxt 3 you can follow this answer

How to pass env variables to nuxt in production?
nuxt.config.js modules: [ ‘@nuxtjs/dotenv’ ], server/index.js const express = require(‘express’)const consola = require(‘consola’)const { Nuxt, Builder } = require(‘nuxt’)const app = ex...

You create .env file with

to connect these values you can use dotenv library, but I prefere Makefile like this one

include .env

node_modules: package.json
	npm i

up: node_modules
	npm run dev

In nuxt config you should add

export default defineNuxtConfig({
    runtimeConfig: {
        public: {
            googleClientId: process.env.GOOGLE_CLIENT_ID ?? '',

and finally in component you can get access to config by

const config = useRuntimeConfig()

Extending window by callback function

Window by default do not have  googleLoginCallback so to add it you should create file types/global.d.ts with

declare global {
    interface Window {
        googleLoginCallback: () => void;

and in component add

if(process.client) {
  window.googleLoginCallback = (...args) => {

Load the client library in Nuxt 3

Google mentions about this step on page

Load the client library | Authentication | Google Developers

But you should not add

<script src="" async defer></script>

in nuxt3, Instead use this code in your component:

  script: [{
    async: true,
    src: '',
    defer: true

Now you should see login button. You should be able to click on it, login and see credentials in console. Assuming that you correctly configured OAuth 2.0 Client

And added localhost to Authorized JavaScript origins

After login in console you will see array with single object like this

  credential: "token"

Credentail token is JWT with payload

  "iss": "",
  "nbf": 1676544985,
  "aud": "",
  "sub": "108561822785941523583",
  "email": "",
  "email_verified": true,
  "azp": "",
  "name": "Daniel Gustaw",
  "picture": "",
  "given_name": "Daniel",
  "family_name": "Gustaw",
  "iat": 1676545285,
  "exp": 1676548885,
  "jti": "a7e1afd716925de385bf0069c7c370f8e64580d3"

To verify it you should send it to backend.

Backend verification for Google credential

As backend we can use fastify. I described fastify config on this blog here

Login by Metamask - Rest Backend in Fastify (Node, Typescript, Prisma) Part 1/2
We building from scratch rest api in fastify using mongodb connected by prisma as database, jest as test framework and etherjs to verify signatures signed by metamask.

so now I assume you have done step "Add Fastify with first endpoint" from this article.

In fastify.ts we can add line with path'/google-verify', Auth.googleVerify)

and in routes/Auth.ts define static function googleVerify.

So in googleVerify we will to check if credentials are correctly created by google.

Checking credentials authenticity

To verify we need install google package on backend according to instruction

Verify the Google ID token on your server side | Authentication | Google Developers
npm install google-auth-library --save

we need the same GOOGLE_CLIENT_ID in backend .env

in file with controller - routes/Auth.ts we can write our function as

import {FastifyRequest} from "fastify";
import {OAuth2Client} from 'google-auth-library';

export class Auth {
  static async googleVerify(req: FastifyRequest<{ Body: { credential: string } }>) {
    const client = new OAuth2Client(process.env.GOOGLE_CLIENT_ID);
    const ticket = await client.verifyIdToken({
      idToken: req.body.credential,
      audience: process.env.GOOGLE_CLIENT_ID,
    const payload = ticket.getPayload();
    if(!payload) throw new Error(`No payload`);
    return payload;

and now update frontend part. First global.d.ts

interface GoogleAuthenticatedResponse {
    clientId: string
    client_id: string
    credential: string
    select_by: "auto"

declare global {
    interface Window {
        googleLoginCallback: (userData: GoogleAuthenticatedResponse) => void;

next add API_URL to .env, then add apiUrl to runtimeConfig like googleClientId, finally we can write callback function in nuxt3 component in form:

if(process.client) {
  window.googleLoginCallback = (userData) => {
    console.log("ud", userData); + '/google-verify', {
      credential: userData.credential
    }).then((res) => {

Enable Cors in Fastify

we forgot about cors

so quick fix

npm i @fastify/cors

and in src/fastify.ts

import cors from '@fastify/cors'



and we can see in console all user's details

We do not want to call await client.verifyIdToken( on any request so we have to exchange google JWT for our own, so it is worth to create user in your database and generate jwt token for him, but I described this in mentione before article:

Login by Metamask - Rest Backend in Fastify (Node, Typescript, Prisma) Part 1/2
We building from scratch rest api in fastify using mongodb connected by prisma as database, jest as test framework and etherjs to verify signatures signed by metamask.