Bird
Raised Fist0
Supabasecloud~30 mins

Magic link authentication in Supabase - Mini Project: Build & Apply

Choose your learning style10 modes available
LearnWhyDeepVisualTryChallengeProjectRecallTime
Magic link authentication
📖 Scenario: You are building a simple web app that lets users log in using a magic link sent to their email. This method avoids passwords and makes login easy and secure.
🎯 Goal: Create a Supabase project setup that enables magic link authentication for users. You will configure the initial user data, set up the authentication config, implement the login function using magic links, and finalize the authentication flow.
📋 What You'll Learn
Create a dictionary with a user email
Add a configuration variable for the redirect URL after login
Write a function to send a magic link using Supabase auth
Complete the authentication setup with the redirect URL
💡 Why This Matters
🌍 Real World
Magic link authentication is used in apps to simplify login without passwords, improving user experience and security.
💼 Career
Understanding magic link authentication is valuable for cloud developers working with modern authentication flows and user management.
Progress0 / 4 steps
1
Create initial user data
Create a dictionary called user_data with a single key email and value "user@example.com".
Supabase
Hint

Use curly braces to create a dictionary and set the key 'email' to the exact string 'user@example.com'.

2
Add redirect URL configuration
Add a variable called redirect_url and set it to "https://yourapp.com/welcome".
Supabase
Hint

Assign the exact URL string to the variable named redirect_url.

3
Implement magic link login function
Write a function called send_magic_link that takes email as a parameter and calls supabase.auth.sign_in_with_otp(email=email, options={"email_redirect_to": redirect_url}).
Supabase
Hint

Define a function with the exact name and parameter. Use the Supabase method sign_in_with_otp passing email as a named argument and options dict as the second.

4
Complete authentication setup
Call the function send_magic_link with the email from user_data to trigger sending the magic link.
Supabase
Hint

Use the exact function name and access the email from the user_data dictionary using the key 'email'.

Practice

(1/5)
1. What is the main purpose of magic link authentication in Supabase?
easy
A. Authenticate users using biometric data like fingerprints
B. Require users to enter a password and a code sent via SMS
C. Use social media accounts for login
D. Allow users to log in by clicking a link sent to their email without using a password

Solution

  1. Step 1: Understand magic link authentication

    Magic link authentication lets users log in by clicking a special link sent to their email, avoiding passwords.

  2. Step 2: Compare options with this definition

    Only Allow users to log in by clicking a link sent to their email without using a password describes login via email link without passwords, matching the magic link concept.

  3. Final Answer:

    Allow users to log in by clicking a link sent to their email without using a password -> Option D

  4. Quick Check:

    Magic link = login via email link without password [OK]
Hint: Magic link means login by email link, no password needed [OK]
Common Mistakes:
  • Confusing magic link with password or biometric login
  • Thinking magic link requires SMS codes
  • Assuming social login is magic link
2. Which is the correct way to call Supabase's magic link sign-in method in JavaScript?
easy
A. supabase.auth.signInWithPassword({ email: 'user@example.com' })
B. supabase.auth.signInWithOtp({ email: 'user@example.com' })
C. supabase.auth.signInWithMagicLink('user@example.com')
D. supabase.auth.loginWithOtp('user@example.com')

Solution

  1. Step 1: Recall Supabase magic link method name

    The correct method is signInWithOtp with an object containing the email.

  2. Step 2: Match method and parameter format

    supabase.auth.signInWithOtp({ email: 'user@example.com' }) uses signInWithOtp with an object { email: '...' }, which is correct syntax.

  3. Final Answer:

    supabase.auth.signInWithOtp({ email: 'user@example.com' }) -> Option B

  4. Quick Check:

    Method name and parameter object = supabase.auth.signInWithOtp({ email: 'user@example.com' }) [OK]
Hint: Use signInWithOtp with email in an object [OK]
Common Mistakes:
  • Using wrong method names like signInWithPassword
  • Passing email as a string instead of an object
  • Confusing method names with social login
3. What will the following code do?
const { data, error } = await supabase.auth.signInWithOtp({ email: 'test@example.com' });
console.log(data);
console.log(error);
medium
A. Send a magic link to 'test@example.com' and log data with confirmation info, error null
B. Return error because email format is invalid
C. Throw a syntax error because signInWithOtp requires a password
D. Send a magic link to 'test@example.com' and log data with user info, error null

Solution

  1. Step 1: Understand signInWithOtp behavior

    This method sends a magic link to the email and returns data about the request, not user info immediately.

  2. Step 2: Analyze console output

    Data contains confirmation info about sending the link; error is null if successful. No syntax error or invalid email here.

  3. Final Answer:

    Send a magic link to 'test@example.com' and log data with confirmation info, error null -> Option A

  4. Quick Check:

    signInWithOtp sends link, returns confirmation data [OK]
Hint: signInWithOtp returns confirmation data, not user info [OK]
Common Mistakes:
  • Expecting immediate user info in data
  • Thinking password is required
  • Assuming invalid email error for valid format
4. You wrote this code but users report they never receive magic links:
await supabase.auth.signInWithOtp('user@example.com');

What is the problem?
medium
A. The method name is incorrect, should be signInWithMagicLink
B. Magic links require a password parameter
C. The email should be passed inside an object, not as a string
D. You must call a separate sendMagicLink function after signInWithOtp

Solution

  1. Step 1: Check method parameter format

    signInWithOtp expects an object with an email property, not a plain string.

  2. Step 2: Identify why magic link is not sent

    Passing a string causes the method to fail silently or not send the email, so users get no link.

  3. Final Answer:

    The email should be passed inside an object, not as a string -> Option C

  4. Quick Check:

    Email must be in object for signInWithOtp [OK]
Hint: Pass email as { email: '...' }, not just a string [OK]
Common Mistakes:
  • Passing email as string instead of object
  • Thinking password is needed for magic link
  • Using wrong method names
5. You want to implement magic link login but only allow users with emails from 'example.com'. Which approach is best?
hard
A. Before calling signInWithOtp, check if email ends with '@example.com' and reject others
B. Call signInWithOtp for all emails, then filter users after login
C. Use signInWithOtp and set a password for domain restriction
D. Configure Supabase to block all emails except 'example.com' automatically

Solution

  1. Step 1: Understand domain restriction needs

    To restrict login to a domain, validate the email before sending magic link.

  2. Step 2: Choose best practice

    Checking email domain in your app before calling signInWithOtp prevents sending links to unauthorized users.

  3. Final Answer:

    Before calling signInWithOtp, check if email ends with '@example.com' and reject others -> Option A

  4. Quick Check:

    Pre-check email domain before magic link send [OK]
Hint: Validate email domain before sending magic link [OK]
Common Mistakes:
  • Sending magic links to all emails then filtering
  • Thinking password is needed for domain restriction
  • Assuming Supabase blocks domains automatically
Recommended

Ready to prove it?

Pass the test and this pattern moves unknown strong while earning +1 Grip toward your certificate.

10 questions~5 mineasy hard