This guide will demonstrate how to integrate Authsignal with Auth0 by creating a Custom Action for the Login / Post-Login trigger. The end result will be to allow users to complete an MFA challenge after they login with their username and password, redirecting them from the Auth0 Universal Login Page to Authsignal’s pre-built UI. The integration follows Auth0’s official guidelines for redirecting users after login to do custom MFA. You can learn more here about how to Redirect with Actions in Auth0.

​
User flow

1

The user enters their username and password in the Auth0 Universal Login page

Auth0 login screen.
2

The user is redirected to Authsignal's pre-built UI to complete an MFA challenge

Pre-built UI challenge screen.
3

The user is logged in if the challenge is completed successfully

​
Integration steps

1

Create an action

In the Auth0 Dashboard, go to Actions → Library and select “Build Custom”. Then select the “Login / Post Login” trigger and give the action an appropriate name (for example “post-login-mfa”).
Screenshot of creating a custom action in Auth0
2

Add your secret

Now your action has been created, create a new secret called AUTHSIGNAL_SECRET and provide the value of your secret from the Api Keys section in the Authsignal Portal.
Screenshot of defining the AUTHSIGNAL_SECRET in Auth0
3

Add dependencies

Add the @authsignal/node dependency.
Screenshot of adding the Authsignal Node SDK as a dependency in Auth0
4

Add the action code

Add the following code snippet to the action.
const { handleAuth0ExecutePostLogin, handleAuth0ContinuePostLogin } = require("@authsignal/node");

exports.onExecutePostLogin = handleAuth0ExecutePostLogin;

exports.onContinuePostLogin = handleAuth0ContinuePostLogin;
If using a non-US region (e.g. AU or EU) you will need to override the API URL as follows:
const { handleAuth0ExecutePostLogin, handleAuth0ContinuePostLogin } = require("@authsignal/node");

const apiUrl = "https://eu.api.authsignal.com/v1";

exports.onExecutePostLogin = async (event, api) => {
  await handleAuth0ExecutePostLogin(event, api, { apiUrl });
};

exports.onContinuePostLogin = async (event, api) => {
  await handleAuth0ContinuePostLogin(event, api, { apiUrl });
};
5

Connect your action to the Login flow

Now connect your action in the Flows section of the Auth0 Dashboard by dragging it into the Login flow.
Auth0 login screen
6

Configure the action in Authsignal

Once the previous steps have been completed, the next time the Auth0 action is run you will see an action appear in the Authsignal Portal called “Auth0 Login”. You will need to set the default outcome for this action to Challenge and save it.
Screenshot of setting the default action outcome in Auth0
That’s it! You’ve done everything required to add MFA to your Auth0 login flow using Authsignal.

​
Next steps