Magic links
Magic links are a passwordless authentication method that allows users to log in by clicking a unique, time-sensitive link sent to their email.

Key Features:

• Passwordless: No need for users to create or remember passwords.
• Secure: Links are time-sensitive and can only be used once, reducing the risk of unauthorized access.
• User-Friendly: Simplifies the login process, especially for non-technical users.

Example Use Cases:

• Applications where quick, seamless authentication is important (e.g., productivity tools, SaaS platforms).
• Reducing friction during onboarding or login processes.
• Enhancing security by eliminating password-related vulnerabilities (e.g., phishing, weak passwords).

Main Weaknesses of Magic Links:

1. Dependency on Email:

   • Magic links rely on the user’s access to their email account. If the email account is compromised, the security of the magic link is also compromised.

   • Users with limited or no access to their email (e.g., due to downtime or spam filters) cannot log in.

2. Delayed Authentication:

   • Users must wait for the email to arrive, which can introduce delays, especially if the email is slow to deliver or ends up in the spam folder.

3. Single-Use and Time-Sensitive:

   • Magic links expire after a short period or after being used once. If the user doesn’t click the link in time, they must request a new one, which can be frustrating.

4. Limited Device Flexibility:

   • If the user clicks the magic link on a different device than the one they initiated the login on, it can create confusion or require additional steps to complete the login.

5. Security Risks with Email:

   • If an attacker gains access to the user’s email account, they can easily log in using the magic link.

   • Email is not inherently secure, and phishing attacks targeting email accounts remain a significant risk.

6. No Multi-Factor Authentication (MFA):

   • Magic links alone do not provide an additional layer of security (e.g., a second factor like SMS or an authenticator app), which may be required for high-security applications.

Bad Fits for Magic Links:

1. High-Security Applications:

   • Applications handling sensitive data (e.g., banking, healthcare) may require stronger authentication methods, such as MFA or hardware tokens, to meet compliance standards.

2. Offline or Low-Connectivity Environments:

   • Magic links require an internet connection to access email. In offline or low-connectivity environments, this method may not work.

3. Applications with Frequent Logins:

   • For applications where users log in frequently (e.g., productivity tools), requiring a magic link every time can become cumbersome and inefficient.

4. Non-Email Users:

   • Applications targeting users who do not regularly use email (e.g., younger audiences or specific demographics) may find magic links ineffective.

5. Shared or Public Devices:

   • Magic links are not ideal for shared or public devices (e.g., library computers) because the link remains active for a short time, and anyone with access to the device could use it.

6. Legacy Systems:

   • Systems that rely on traditional username/password authentication or legacy infrastructure may struggle to integrate magic links seamlessly.

Mitigation Strategies:

• Combine magic links with MFA for added security.

• Use fallback authentication methods (e.g., OTP via SMS) for users who cannot access their email.

• Provide clear instructions and user education to minimize confusion.

Example
How to use magic links in Supabase

From: How to use magic links in Supabase