How to build Mailgun Email passwordless sign-in with Webflow

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Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

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

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of Webflow.
A usable Mailgun account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Single page app application, simply follow these steps:

Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
In the opening modal, click the "Single page app" section or filter all the available "Single page app" frameworks using the quick filter checkboxes on the left. Click the "Webflow" framework card to start creating your application.
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 Webflow with Logto

tip:

The sample project is available at Webflow project preview.

Init Logto Provider

note:

In the following steps, we assume your Webflow site is running on https://your-awesome-site.webflow.io.

In this step, we'll add global-level custom code to your Webflow site. Since NPM is not supported in Webflow, we'll use the jsdelivr.com CDN service to import the Logto SDK.

Open the "Site settings" page, and navigate to the "Custom code" section. Add the following code to the "Head code" section.

<script type="module">
  // Import \`@logto/browser\` SDK from the jsdelivr CDN
  import LogtoClient from 'https://esm.run/@logto/browser';

  // Assign the \`logtoClient\` instance to window object,
  // enabling global usage in other pages
  window.logtoClient = new LogtoClient({
    endpoint: '<your-logto-endpoint>', // E.g. http://localhost:3001
    appId: '<your-application-id>',
  });
</script>

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:

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

This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
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.

Let's switch to the Application details page of Logto Console. Add a Redirect URI https://your-awesome-site.webflow.io/callback and click "Save changes".

Return to your Webflow designer, drag and drop a "Sign in" button to the home page, and assign it an ID “sign-in” for later reference using getElementById().

<script type="module">
  const signInButton = document.getElementById('sign-in');
  const onClickSignIn = () => logtoClient.signIn('https://your-awesome-site.webflow.io/callback');
  signInButton.addEventListener('click', onClickSignIn);
</script>

Handle redirect

We're almost there! In the last step, we use https://your-awesome-site.webflow.io/callback as the Redirect URI, and now we need to handle it properly.

First let's create a "Callback" page in Webflow, and simply put some static text "Redirecting..." on it. Then add the following page-level custom code to "Callback" page.

<script type="module">
  (async () => {
    // Handle sign-in callback logic by calling the SDK method
    await logtoClient.handleSignInCallback(window.location.href);

    // Redirect back to the home page when the handling is done
    window.location.assign('https://your-awesome-site.webflow.io');
  })();
</script>

Implement sign-out

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

After signing out, it'll be great to redirect your user back to your website. Let's add https://your-awesome-site.webflow.io as one of the Post Sign-out URIs in Admin Console (shows under Redirect URIs), and use the URL as the parameter when calling .signOut().

Implement a sign-out button

Return to the Webflow designer, and add a “Sign out” button on your home page. Similarly, assign an ID “sign-out” to the button, and add the following code to the page-level custom code.

const signOutButton = document.getElementById('sign-out');
const onClickSignOut = () => logtoClient.signOut('https://your-awesome-site.webflow.io');
signOutButton.addEventListener('click', onClickSignOut);

Handle authentication status

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

In your Webflow site, you can also use it to programmatically show and hide the sign-in and sign-out buttons. Apply the following custom code to adjust button CSS accordingly.

const isAuthenticated = await logtoClient.isAuthenticated();

signInButton.style.display = isAuthenticated ? 'none' : 'block';
signOutButton.style.display = isAuthenticated ? 'block' : 'none';

Checkpoint: Test your Webflow site

Now, test your site:

Deploy and visit your site URL, the sign-in button should be visible.
Click the sign-in button, the SDK will initiate the sign-in process, redirecting you to the Logto sign-in page.
After signing in, you will be redirected back to your site, seeing the username and the sign-out button.
Click the sign-out button to sign-out.

Add Mailgun connector

Email connector is a method used to send one-time passwords (OTPs) for authentication. It enables Email address verification to support passwordless authentication, including Email-based registration, sign-in, two-factor authentication (2FA), and account recovery. You can easily connect Mailgun as your Email provider. With the Logto Email connector, you can set this up in just a few minutes.

To add a Email connector, simply follow these steps:

Navigate to Console > Connector > Email and SMS connectors.
To add a new Email connector, click the "Set up" button and select "Mailgun".
Review the README documentation for your selected provider.
Complete the configuration fields in the "Parameter Configuration" section.
Customize the Email template using the JSON editor.
Test your configuration by sending a verification code to your Email address.

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up Mailgun email connector

Prerequisites

A Mailgun account
An API key from your Mailgun account, requires the permission to send messages (emails). See Where Can I Find My API Key and SMTP Credentials? for more information.

Basic configuration

Fill out the endpoint field when you are using a different Mailgun API endpoint, for example, EU region should be https://api.eu.mailgun.net. The default value is https://api.mailgun.net.
Fill out the domain field with the domain you have registered in your Mailgun account. This value can be found in the Domains section of the Mailgun dashboard. The domain should be in the format example.com, without the https:// or http:// prefix.
Fill out the apiKey field with the API key you have generated in your Mailgun account.
Fill out the from field with the email address you want to send emails from. This email address must be registered in your Mailgun account. The email address should be in the format Sender Name \<[email protected]>.

Deliveries

Config object

The "Deliveries" section allows you to configure the content of the emails to be sent in different scenarios. It is a JSON key-value map where the key is the usage type and the value is an object containing the content config for the email to be sent.

{
  "<usage-type>": {
    // ...
  }
}

Usage types

The following usage types are supported:

Register: The email to be sent when a user is registering.
SignIn: The email to be sent when a user is signing in.
ForgotPassword: The email to be sent when a user is resetting their password.
Generic: The email to be sent when a user is performing a generic action, for example, testing the email connector.

note:

If the usage type is not specified in the deliveries config, the generic email will be sent. If the generic email is not specified, the connector will return an error.

Content config

The connector supports both direct HTML content and Mailgun template. You can use one of them for each usage type.

In both subject and content, you can use the {{code}} placeholder to insert the verification code.

To use direct HTML content, fill out the following fields:

subject: The subject of the email to be sent.
replyTo: The email address to be used as the reply-to address.
html: (Required) The HTML content of the email to be sent.
text: The plain text version of the email to be sent.

To use Mailgun template, fill out the following fields:

subject: The subject of the email to be sent.
replyTo: The email address to be used as the reply-to address.
template: (Required) The name of the Mailgun template to be used.
variables: The variables to be passed to the Mailgun template. Should be a JSON key-value map since it will be stringified before sending to Mailgun. Note there's no need to include the code variable since it will be automatically added by the connector.

Example

The following is an example of the deliveries config:

{
  "Register": {
    "subject": "{{code}} is your verification code",
    "replyTo": "Foo <[email protected]>",
    "html": "<h1>Welcome to Logto</h1><p>Your verification code is {{code}}.</p>",
    "text": "Welcome to Logto. Your verification code is {{code}}."
  },
  "SignIn": {
    "subject": "Welcome back to Logto",
    "replyTo": "Foo <[email protected]>",
    "template": "logto-sign-in",
    "variables": {
      "bar": "baz"
    }
  }
}

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 Mailgun connector should be available now.

Once you create a connector successfully, you can enable phone number-based passwordless login and registration.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
Set up sign-up methods (Optional):
1. Select "Email address" or "Email or phone number" as the sign-up identifier.
2. "Verify at sign-up" is forced to be enabled. You can also enable "Create a password" on registration.
Set up sign-in methods:
1. Select Email address as one of sign-in identifiers. You can provide multiple available identifiers (email, phone number, and username).
2. Select "Verification code" and / or "Password" as the authentication factor.
Click "Save changes" and test it in "Live preview".

In addition to registration and login via OTPs, you can also have password recovery and -based security verification enabled, as well as linking Email address to profile. See End-user flows for more details.

Testing and Validation

Return to your Webflow app. You should now be able to sign in with Mailgun. Enjoy!

Create an application in Logto​

Integrate Webflow with Logto​

Init Logto Provider​

Implement sign-in​

Regarding redirect-based sign-in​

Configure sign-in redirect URI​

Implement a sign-in button​

Handle redirect​

Implement sign-out​

Implement a sign-out button​

Handle authentication status​

Checkpoint: Test your Webflow site​

Add Mailgun connector​

Set up Mailgun email connector​

Prerequisites​

Basic configuration​

Deliveries​

Config object​

Usage types​

Content config​

Example​

Save your configuration​

Enable Mailgun connector in Sign-in Experience​

Testing and Validation​

Further readings​

Create an application in Logto

Integrate Webflow with Logto

Init Logto Provider

Implement sign-in

Regarding redirect-based sign-in

Configure sign-in redirect URI

Implement a sign-in button

Handle redirect

Implement sign-out

Implement a sign-out button

Handle authentication status

Checkpoint: Test your Webflow site

Add Mailgun connector

Set up Mailgun email connector

Prerequisites

Basic configuration

Deliveries

Config object

Usage types

Content config

Example

Save your configuration

Enable Mailgun connector in Sign-in Experience

Testing and Validation

Further readings