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 SendGrid sign-in experience (user authentication) with Vanilla JS and  Logto.

Prerequisites

• A running Logto instance. Check out the get started page if you don't have one.
• Basic knowledge of Vanilla JS.
• A usable SendGrid 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 "Single page app" section or filter all the available " Single page app" frameworks using the quick filter checkboxes on the left.

Click the "Vanilla JS" 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

tip

• The vanilla-js SDK is framework-agnostic, you can use it in any frontend framework by writing a wrapper to fit it.
• The sample project is available on our SDK repository.

Installation

Choose your favorite package manager or use the CDN to install the Logto Browser SDK.

npm

npm i @logto/browser

pnpm

pnpm add @logto/browser

yarn

yarn add @logto/browser

CDN

<!-- Special thanks to jsdelivr -->
<script type="module">
  import LogtoClient from 'https://cdn.jsdelivr.net/npm/@logto/[email protected]/+esm';
</script>

Init LogtoClient

Import and init a LogtoClient instance by passing config:

index.js

import LogtoClient from '@logto/browser';

const logtoClient = new LogtoClient({
  endpoint: '<your-logto-endpoint>',
  appId: '<your-application-id>',
});

The endpoint and appId can be found in the application details page in Logto Console.

Implement a sign-in and sign-out

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.

---

note

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.

Handle redirect

There are still things to do after the user is redirected back to your application from Logto. Let's handle it properly.

pages/Callback.js

const callbackHandler = async (logtoClient) => {
  await logtoClient.handleSignInCallback(window.location.href);

  if (!logtoClient.isAuthenticated) {
    // Handle failed sign-in
    alert('Failed to sign in');
    return;
  }

  // Handle successful sign-in
  window.location.assign('/');
};

Implement sign-in and sign-out

logtoClient provides signIn and signOut methods to help you easily manage the authentication flow.

note

Before calling .signIn(), make sure you have correctly configured Redirect URI in Admin Console.

pages/Home.js

const isAuthenticated = await logtoClient.isAuthenticated();

const onClickSignIn = () => {
  logtoClient.signIn('http://localhost:3000/callback');
};
const onClickSignOut = () => {
  logtoClient.signOut('http://localhost:3000');
};

const button = document.createElement('button');
button.innerHTML = isAuthenticated ? 'Sign Out' : 'Sign In';
button.addEventListener('click', isAuthenticated ? onClickSignOut : onClickSignIn);

document.body.appendChild(button);

Calling .signOut() will clear all the Logto data in memory and localStorage if they exist.

Handle authentication status

In Logto SDK, generally we can use logtoClient.isAuthenticated to check the authentication status, if the user is signed in, the value will be true, otherwise, the value will be false.

In your vanilla JS app, you can use the isAuthenticated status to programmatically show and hide the sign-in and sign-out buttons. Let's see how to do it.

const redirectUrl = 'http://localhost:3000/callback';
const baseUrl = 'http://localhost:3000';

// Conditional rendering of sign-in and sign-out buttons
const render = async (logtoClient) => {
  const isAuthenticated = await logtoClient.isAuthenticated();
  const container = document.querySelector('#container');

  const onClickSignIn = () => logtoClient.signIn(redirectUrl);
  const onClickSignOut = () => logtoClient.signOut(baseUrl);

  const button = document.createElement('button');
  button.innerHTML = isAuthenticated ? 'Sign Out' : 'Sign In';
  button.addEventListener('click', isAuthenticated ? onClickSignOut : onClickSignIn);

  container.append(button);
};

Test your integration

Open your Vanilla JS app to test if the integration works. When you click the "Sign In" button, the page should be redirected to a Logto sign-in page, and you should be able to create a new account by entering username and password and complete the sign-in process.

Add SendGrid connector

To add or change Email connector, go to the "Connector" tab in the Admin Console, then click on "Email and SMS connectors". From there, click "Set up" or go to detail page and click "Change Email connector".

In the openning modal, select "SendGrid" 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 SendGrid email connector

Register SendGrid account

Create a new account at SendGrid website. You may skip this step if you've already registered an account.

Verify senders

Go to the SendGrid console page and sign in with your SendGrid account.

Senders indicate the addresses our verification code email will be sent from. In order to send emails via the SendGrid mail server, you need to verify at least one sender.

Starting from the SendGrid console page, go to "Settings" -> "Sender Authentication" from the sidebar.

Domain Authentication is recommended but not obligatory. You can click "Get Started" in "Authenticate Your Domain" card and follow the upcoming guide to link and verify a sender to SendGrid.

By clicking the "Verify a Single Sender" button in the panel, you are now focusing on a form requiring some critical information to create a sender. Follow the guide, fill out all these fields, and hit the "Create" button.

After the single sender is created, an email with a verification link should be sent to your sender's email address. Go to your mailbox, find the verification mail and finish verifying the single sender by clicking the link given in the email. You can now send emails via SendGrid connector using the sender you've just verified.

Create API keys

Let's start from the SendGrid console page, go to "Settings" -> "API Keys" from the sidebar.

Click the "Create API Key" in the top-right corner of the API Keys page. Type in the name of the API key and customize "API Key Permission" per your use case. A global Full Access or Restricted Access with full access to Mail Send is required before sending emails with this API key.

The API Key is presented to you on the screen as soon as you finished the Create API Key process. You should save this API Key somewhere safe because this is the only chance that you can see it.

Configure your connector

Fill out the apiKey field with the API Key created in "Create API keys" section.

Fill out the fromEmail and fromName fields with the senders' From Address and Nickname. You can find the sender's details on the "Sender Management" page. fromName is OPTIONAL, so you can skip filling it.

You can add multiple SendGrid mail connector templates for different cases. Here is an example of adding a single template:

• Fill out the subject field, which works as the title of emails.
• Fill out the content field with arbitrary string-typed contents. Do not forget to leave the {{code}} placeholder for the random verification code.
• Fill out usageType field with either Register, SignIn, ForgotPassword, Generic for different use cases.
• Fill out type field with either text/plain or text/html for different types of content.

In order to enable full user flows, templates with usageType Register, SignIn, ForgotPassword and Generic are required.

Here is an example of SendGrid connector template JSON.

[
  {
    "subject": "<register-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (register template)>",
    "usageType": "Register",
    "type": "text/plain",
  },
  {
    "subject": "<sign-in-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (sign-in template)>",
    "usageType": "SignIn",
    "type": "text/plain",
  },
  {
    "subject": "<forgot-password-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (forgot-password template)>",
    "usageType": "ForgotPassword",
    "type": "text/plain",
  },
  {
    "subject": "<generic-template-subject>",
    "content": "<Logto: Your verification code is {{code}}. (generic template)>",
    "usageType": "Generic",
    "type": "text/plain",
  },
]

Test SendGrid Email connector

You can type in an email address and click on "Send" to see whether the settings can work before "Save and Done".

That's it. Don't forget to enable connector in sign-in experience.

Config types

Name	Type
apiKey	string
fromEmail	string
fromName	string (OPTIONAL)
templates	Template[]

Template Properties	Type	Enum values
subject	string	N/A
content	string	N/A
usageType	enum string	'Register' | 'SignIn' | 'ForgotPassword' | 'Generic'
type	enum string	'text/plain' | 'text/html'

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 SendGrid connector should be available now.

Enable SendGrid connector in Sign-in Experience

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

note

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 "Email address" or "Email address or phone number" for the "Sign-up identifier" to provide sign-up for Email passwordless sign-in, which may increase your conversion rate.

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

Testing and Validation

Return to your Vanilla JS app. You should now be able to sign in with SendGrid. 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.

🧑‍🚀 Manage users 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.