When enhancing your authentication flow in React apps, you have two main options: using Auth0 Lock—a ready-made login widget provided by Auth0—or building a fully custom login interface with Auth0 APIs. Auth0 Lock is a drop-in authentication solution that offers a polished, secure, and customizable user interface for logging in and signing up. It supports features like social logins, passwordless authentication, multi-language support, and branding options such as custom logos and color themes. With minimal setup, Lock handles form validation, error messages, and accessibility best practices, allowing you to quickly implement authentication without designing your own UI from scratch.

If you need more control over the user experience, you can create a custom login UI using Auth0's authentication endpoints and React components. This approach lets you design the interface to match your application's style and user flow precisely. However, it requires you to handle form validation, error feedback, accessibility, and integration with Auth0's authentication API manually. You will need to collect user credentials, send them securely to Auth0, and process authentication responses, including handling tokens and errors.

To implement a custom login UI in React with Auth0, follow these steps:

1. Create a login form component using React, with fields for email/username and password;
2. Capture form input and handle submission with state and event handlers;
3. On submit, call Auth0's authentication API endpoint (/oauth/token) with the user credentials;
4. Process the response: if successful, store the returned tokens according to your session management strategy;
5. Display error messages for failed authentication attempts;
6. Redirect users upon successful login to the appropriate page in your app.

This method gives you flexibility in design and user flow, but you must ensure security and compliance with best practices, such as secure handling of credentials and proper error messaging.