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 Twilio sign-in experience (user authentication) with Python and Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of Python.
• A usable Twilio 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 Traditional web application, simply follow these steps:

1. 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.
2. In the opening modal, click the "Traditional web" section or filter all the available "Traditional web" frameworks using the quick filter checkboxes on the left. Click the "Flask" framework card to start creating your application.
3. 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 example uses Flask, but the concepts are the same for other frameworks.
• The Python sample project is available on our Python SDK repo.
• Logto SDK leverages coroutines, remember to use await when calling async functions.

Installation

Execute in the project root directory:

pip install logto # or `poetry add logto` or whatever you use

Init LogtoClient

First, create a Logto config:

client.py

from logto import LogtoClient, LogtoConfig

client = LogtoClient(
    LogtoConfig(
        endpoint="https://you-logto-endpoint.app",  # Replace with your Logto endpoint
        appId="replace-with-your-app-id",
        appSecret="replace-with-your-app-secret",
    ),
)

tip:

You can find and copy "App Secret" from application details page in Admin Console:

Also replace the default memory storage with a persistent storage, for example:

client.py

from logto import LogtoClient, LogtoConfig, Storage
from flask import session
from typing import Union

class SessionStorage(Storage):
    def get(self, key: str) -> Union[str, None]:
        return session.get(key, None)

    def set(self, key: str, value: Union[str, None]) -> None:
        session[key] = value

    def delete(self, key: str) -> None:
        session.pop(key, None)

client = LogtoClient(
    LogtoConfig(...),
    storage=SessionStorage(),
)

See Storage for more details.

Implement sign-in and sign-out

In your web application, add a route to properly handle the sign-in request from users. Let's use /sign-in as an example:

flask.py

@app.route("/sign-in")
async def sign_in():
  # Get the sign-in URL and redirect the user to it
  return redirect(await client.signIn(
      redirectUri="http://localhost:3000/callback",
  ))

Replace http://localhost:3000/callback with the callback URL you set in your Logto Console for this application.

If you want to show the sign-up page on the first screen, you can set interactionMode to signUp:

flask.py

@app.route("/sign-in")
async def sign_in():
  return redirect(await client.signIn(
      redirectUri="http://localhost:3000/callback",
      interactionMode="signUp", # Show the sign-up page on the first screen
  ))

Now, whenever your users visit http://localhost:3000/sign-in, it will start a new sign-in attempt and redirect the user to the Logto sign-in page.

Note Creating a sign-in route isn't the only way to start a sign-in attempt. You can always use the signIn method to get the sign-in URL and redirect the user to it.

After the user makes a signing-out request, Logto will clear all user authentication information in the session.

To clean up the Python session and Logto session, a sign-out route can be implemented as follows:

flask.py

@app.route("/sign-out")
async def sign_out():
  return redirect(
      # Redirect the user to the home page after a successful sign-out
      await client.signOut(postLogoutRedirectUri="http://localhost:3000/")
  )

Handle authentication status

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

Here we also implement a simple home page for demonstration:

• If the user is not signed in, show a sign-in button;
• If the user is signed in, show a sign-out button.

@app.route("/")
async def home():
    if client.isAuthenticated() is False:
        return "Not authenticated <a href='/sign-in'>Sign in</a>"
    return "Authenticated <a href='/sign-out'>Sign out</a>"

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 token storage and sign out.

Add Twilio connector

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

To add a SMS connector, simply follow these steps:

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

note:

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

Set up Twilio SMS connector

Register Twilio account

Create a new account on Twilio. (Jump to the next step if you already have one.)

Set up senders' phone numbers

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

Purchase a phone number under "Phone Numbers" -> "Manage" -> "Buy a number".

tip:

Sometimes you may encounter the situation that SMS service is not supported in specific countries or areas. Pick a number from other regions to bypass.

Once we have a valid number claimed, nav to the "Messaging" -> "Services". Create a new Message Service by clicking on the button.

Give a friendly service name and choose Notify my users as our service purpose. Following the next step, choose Phone Number as Sender Type, and add the phone number we just claimed to this service as a sender.

note:

Each phone number can only be linked with one messaging service.

Get account credentials

We will need the API credentials to make the connector work. Let's begin from the Twilio console page.

Click on the "Account" menu in the top-right corner, then go to the "API keys & tokens" page to get your Account SID and Auth token.

Back to "Messaging" -> "Services" settings page starting from the sidebar, and find the Sid of your service.

Compose the connector JSON

Fill out the accountSID, authToken and fromMessagingServiceSID fields with Account SID, Auth token and Sid of the corresponding messaging service.

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

• Fill out the content field with arbitrary string-typed contents. Do not forget to leave {{code}} placeholder for random verification code.
• Fill out the usageType field with either Register, SignIn, ForgotPassword, Generic for different use cases. In order to enable full user flows, templates with usageType Register, SignIn, ForgotPassword and Generic are required.

Test Twilio SMS connector

You can enter a phone number 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
accountSID	string
authToken	string
fromMessagingServiceSID	string
templates	Templates[]

Template Properties	Type	Enum values
content	string	N/A
usageType	enum string	'Register' | 'SignIn' | 'ForgotPassword' | 'Generic'

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 Twilio connector should be available now.

Enable Twilio connector in Sign-in Experience

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

1. Navigate to Console > Sign-in experience > Sign-up and sign-in.
2. Set up sign-up methods (Optional):
   1. Select "Phone number" 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.
3. Set up sign-in methods:
   1. Select Phone number 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.
4. 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 Phone number to profile. See End-user flows for more details.

Testing and Validation

Return to your Python app. You should now be able to sign in with Twilio. Enjoy!

Further readings

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

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