How to build SendGrid Email passwordless sign-in with Capacitor JS

For our new friends:

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

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of Capacitor JS.
A usable SendGrid 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 Native 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 "Native app" section or filter all the available "Native app" frameworks using the quick filter checkboxes on the left. Click the "Capacitor JS" 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 Capacitor JS with Logto

astuce:

The following demonstration is built on Capacitor JS 5.0.6.

Installation

Install Logto SDK and peer dependencies via your favorite package manager:

npm
Yarn
pnpm

npm i @logto/capacitor
npm i @capacitor/browser @capacitor/app @capacitor/preferences

yarn add @logto/capacitor
yarn add @capacitor/browser @capacitor/app @capacitor/preferences

pnpm add @logto/capacitor
pnpm add @capacitor/browser @capacitor/app @capacitor/preferences

The @logto/capacitor package is the SDK for Logto. The remaining packages are its peer dependencies.

Init Logto client

Add the following code to your Capacitor project:

import LogtoClient, { type LogtoConfig } from '@logto/capacitor';

const logtoConfig: LogtoConfig = {
  endpoint: '<your-logto-endpoint>',
  appId: '<your-application-id>',
};

const logtoClient = new LogtoClient(config);

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.

Now, let's configure the redirect URI. The redirect URI is used to redirect the user back to your application after the authentication flow.

Ensure that the URI redirects to the Capacitor app, for example, com.example.app://callback. The value may vary depending on your Capacitor app configuration. For more details, see Capacitor Deep Links.

Then, add the following code to the onClick handler of the sign-in button:

const onClick = async () => {
  await logtoClient.signIn('com.example.app://callback');
  console.log(await logtoClient.isAuthenticated()); // true
  console.log(await logtoClient.getIdTokenClaims()); // { sub: '...', ... }
};

Implement sign-out

Since Capacitor leverages the Safari View Controller on iOS and Chrome Custom Tabs on Android, the authentication state can be persisted for a while. However, sometimes the user may want to sign out of the application immediately. In this case, we can use the signOut method to sign out the user:

const onClick = async () => {
  await logtoClient.signOut();
  console.log(await logtoClient.isAuthenticated()); // false
};

The signOut method has an optional parameter for the post sign-out redirect URI. If it's not provided, the user will be redirected to the Logto sign-out page.

The user needs to click "Done" to close the web view and return to the Capacitor app. If you want to automatically redirect the user back to the Capacitor app, you can provide the post sign-out redirect URI, for instance, com.example.app://callback/sign-out.

Ensure that the post sign-out redirect URI can redirect to the Capacitor app. Then add the following code to the onClick handler of the sign-out button:

const onClick = async () => {
  await logtoClient.signOut('com.example.app://callback/sign-out');
};

Checkpoint: Trigger the authentication flow

Run the Capacitor app and click the sign-in button. A browser window will open, redirecting to the Logto sign-in page.

If the user closes the browser window without completing the authentication flow, the Capacitor app will receive a LogtoClientError.

Add SendGrid 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 SendGrid 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 "SendGrid".
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.

remarque:

If you are following the in-place Connector 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 got 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.

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 Capacitor JS app. You should now be able to sign in with SendGrid. Enjoy!

Create an application in Logto​

Integrate Capacitor JS with Logto​

Installation​

Init Logto client​

Implement sign-in​

Regarding redirect-based sign-in​

Implement sign-out​

Checkpoint: Trigger the authentication flow​

Add SendGrid connector​

Set up SendGrid email connector​

Register SendGrid account​

Verify senders​

Create API keys​

Configure your connector​

Test SendGrid email connector​

Config types​

Save your configuration​

Enable SendGrid connector in Sign-in Experience​

Testing and Validation​

Further readings​