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Supabasecloud~5 mins

Magic link authentication in Supabase

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Introduction

Magic link authentication lets users sign in by clicking a link sent to their email. It is simple and secure without needing a password.

When you want to make login easy for users without remembering passwords.
When building apps that require quick and secure user access.
When you want to reduce password-related support issues.
When you want to improve user experience with passwordless sign-in.
When you want to increase security by avoiding password theft.
Syntax
Supabase
const { data, error } = await supabase.auth.signInWithOtp({ email: 'user@example.com' })

This code sends a magic link to the user's email.

You only need to provide the user's email address.

Examples
Sends a magic link to Alice's email for login.
Supabase
const { data, error } = await supabase.auth.signInWithOtp({ email: 'alice@example.com' })
Sends a magic link to Bob's email that redirects to a welcome page after login.
Supabase
const { data, error } = await supabase.auth.signInWithOtp({ email: 'bob@example.com', options: { emailRedirectTo: 'https://yourapp.com/welcome' } })
Sample Program

This program creates a Supabase client and sends a magic link to the specified email. It logs success or error messages.

Supabase
import { createClient } from '@supabase/supabase-js'

const supabaseUrl = 'https://xyzcompany.supabase.co'
const supabaseKey = 'public-anonymous-key'
const supabase = createClient(supabaseUrl, supabaseKey)

async function sendMagicLink(email) {
  const { data, error } = await supabase.auth.signInWithOtp({ email })
  if (error) {
    console.error('Error sending magic link:', error.message)
  } else {
    console.log('Magic link sent to:', email)
  }
}

sendMagicLink('user@example.com')
OutputSuccess
Important Notes

Make sure your Supabase project has email authentication enabled.

Users must check their email and click the link to complete login.

You can customize the redirect URL after login using the emailRedirectTo option.

Summary

Magic link authentication lets users log in without passwords by clicking a link sent to their email.

It improves user experience and security by avoiding passwords.

Supabase provides a simple method signInWithOtp to send magic links.

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
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