For our new friends:

Every app needs authentication and authorization. Logto is an Auth0 alternative designed for modern apps and SaaS products.

In this article, we will go through the steps to quickly build the Google sign-in experience (user authentication) with Express and  Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of Express.
• A usable Google account.

Create an application in Logto

In you browser, open a new tab and enter the link of Logto Admin Console.

Once the page is loaded, in the "Get Started" section click the View all link to open the application framework list page.

Choose your application type

In the opening modal, scroll to the "Traditional web" section or filter all the available " Traditional web" frameworks using the quick filter checkboxes on the left.

Click the "Express" framework card to start creating your application.

Enter application name

Enter the application name, e.g., "Bookstore," and click "Create application."

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Logto SDK

astuce:

• The sample project is available on our SDK repository.

Installation

Install Logto SDK via your favorite package manager:

npm

npm i @logto/express cookie-parser express-session

pnpm

pnpm add @logto/express cookie-parser express-session

yarn

yarn add @logto/express cookie-parser express-session

Integration

Prepare configs and required middlewares

Prepare configuration for the Logto client:

app.ts

import { LogtoExpressConfig } from '@logto/express';

const config: LogtoExpressConfig = {
  appId: '<your-application-id>',
  appSecret: '<your-application-secret>',
  endpoint: '<your-logto-endpoint>', // E.g. http://localhost:3001
  baseUrl: '<your-express-app-base-url>', // E.g. http://localhost:3000
};

The SDK requires express-session to be configured in prior.

app.ts

import cookieParser from 'cookie-parser';
import session from 'express-session';

app.use(cookieParser());
app.use(
  session({
    secret: 'random_session_key', // Replace with your own secret
    cookie: { maxAge: 14 * 24 * 60 * 60 * 1000 }, // In miliseconds
  })
);

Configure redirect URIs

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

1. Your app invokes the sign-in method.
2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

---

remarque:

In the following code snippets, we assume your app is running on http://localhost:3000/.

Configure redirect URIs

Switch to the application details page of Logto Console. Add a redirect URI http://localhost:3000/callback.

Just like signing in, users should be redirected to Logto for signing out of the shared session. Once finished, it would be great to redirect the user back to your website. For example, add http://localhost:3000/ as the post sign-out redirect URI section.

Then click "Save" to save the changes.

Register routes

The SDK provides a helper function handleAuthRoutes to register 3 routes:

1. /logto/sign-in: Sign in with Logto.
2. /logto/sign-in-callback: Handle sign-in callback.
3. /logto/sign-out: Sign out with Logto.

Add the following code to your app:

app.ts

import { handleAuthRoutes } from '@logto/express';

app.use(handleAuthRoutes(config));

Implement sign-in and sign-out

With the routes registered, now let's implement the sign-in and sign-out buttons in the home page. We need to redirect the user to the sign-in or sign-out route when needed. To help with this, use withLogto to inject authentication status to req.user.

app.ts

import { withLogto } from '@logto/express';

app.get('/', withLogto(config), (req, res) => {
  res.setHeader('content-type', 'text/html');

  if (req.user.isAuthenticated) {
    res.end(`<div>Hello ${req.user.claims?.sub}, <a href="/logto/sign-out">Sign Out</a></div>`);
  } else {
    res.end('<div><a href="/logto/sign-in">Sign In</a></div>');
  }
});

Checkpoint: Test your application

Now, you can test your application:

1. Run your application, you will see the sign-in button.
2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
3. After you signed in, you will be redirected back to your application and see the sign-out button.
4. Click the sign-out button to clear local storage and sign out.

Add Google connector

To add a social connector, go to the "Connector" tab in the Admin Console, then click on "Social connectors". From there, click "Add social connector".

In the openning modal, select "Google" and click "Next".

On the next page, you will see a two-column layout with the README content on the left and configuration on the right.

Feel free to follow the README file in place or read the following section to complete the configuration process. If you follow the in-place guide, you can skip the next section.

Set up Google OAuth app

Set up a project in the Google API Console

• Visit the Google API Console and sign in with your Google account.
• Click the Select a project button on the top menu bar, and click the New Project button to create a project.
• In your newly created project, click the APIs & Services to enter the APIs & Services menu.

Configure your consent screen

• On the left APIs & Services menu, click the OAuth consent screen button.
• Choose the User Type you want, and click the Create button. (Note: If you select External as your User Type, you will need to add test users later.)

Now you will be on the Edit app registration page.

Config OAuth consent screen

• Follow the instructions to fill out the OAuth consent screen form.
• Click SAVE AND CONTINUE to continue.

Config scopes

• Click ADD OR REMOVE SCOPES and select ../auth/userinfo.email, ../auth/userinfo.profile and openid in the popup drawer, and click UPDATE to finish.
• Fill out the form as you need.
• Click SAVE AND CONTINUE to continue.

Add test users (External user type only)

• Click ADD USERS and add test users to allow these users to access your application while testing.
• Click SAVE AND CONTINUE to continue.

Now you should have the Google OAuth 2.0 consent screen configured.

Obtain OAuth 2.0 credentials

• On the left APIs & Services menu, click the Credentials button.
• On the Credentials page, click the + CREATE CREDENTIALS button on the top menu bar, and select OAuth client ID.
• On the Create OAuth client ID page, select Web application as the application type.
• Fill out the basic information for your application.
• Click + Add URI to add an authorized domain to the Authorized JavaScript origins section. This is the domain that your logto authorization page will be served from. In our case, this will be ${your_logto_origin}. e.g.https://logto.dev.
• Click + Add URI in the **Authorized redirect URIs** section to set up the **Authorized redirect URIs**, which redirect the user to the application after logging in. In our case, this will be ${your_logto_endpoint}/callback/${connector_id}. e.g. https://logto.dev/callback/${connector_id}. The connector_id can be found on the top bar of the Logto Admin Console connector details page.
• Click Create to finish and then you will get the Client ID and Client Secret.

References

Config types

Name	Type
clientId	string
clientSecret	string

Google developer docs

Google Identity: Setting up OAuth 2.0

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Google connector should be available now.

Enable Google connector in Sign-in Experience

Switch to the "Sign-in experience" tab, then click the "Sign-up and sign-in" tab.

remarque:

If it's the first time you enter the tab, you will see a quick introduction about Sign-in Experience and its basic configuration.

Select "None" for the "Sign-up identifier" to provide minimum sign-up effort for Google sign-in, which may increase your conversion rate.

In the "Social sign-in" section, add "Add Social Connector" and choose "Google". Then you should be able to see a button with text "Continue with Google" in the preview section.

Finally, click "Save changes" on the bottom right corner.

Testing and Validation

Return to your Express app. You should now be able to sign in with Google. Enjoy!

Further readings

Protect your API For native and single page apps, you'll need to call one or more API endpoints to retrieve and update data.
Learn more about identifying who's who and keeping your API secure.

User management We know you care about user management and activities, as we also do.
Learn more about how to know your users and see the figures like DAU and MAU graphically.

Localization From one regional business to a global corporate, the willingness to offer the best user experience won't change.
You can change current language phrases or add a new language without friction.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.