#atom

Passwordless login through email-based verification

Core Idea: Magic Link Authentication is a passwordless authentication method where users receive a unique, time-limited URL via email that automatically logs them in when clicked, eliminating the need to remember or input passwords.

Key Elements

• Key principles

  • Passwordless authentication
  • Email as identity verification
  • Time-limited token security
  • Single-use links
  • Lower friction user experience

• Authentication flow

  1. User enters email address on login page
  2. Application generates secure, time-limited token
  3. Token is embedded in a unique URL (magic link)
  4. Link is sent to user's email
  5. User clicks link in email
  6. Application verifies token validity and authenticity
  7. User is authenticated and session created

• Security considerations

  • Short token expiration time (typically 5-15 minutes)
  • Single-use tokens
  • Secure token generation (cryptographically secure)
  • Email delivery confirmation
  • Rate limiting token generation
  • Token storage security

• Implementation example (Node.js with Next.js and Auth.js)

// pages/api/auth/[...nextauth].js
import NextAuth from "next-auth";
import EmailProvider from "next-auth/providers/email";
import { MongoDBAdapter } from "@next-auth/mongodb-adapter";
import clientPromise from "../../../lib/mongodb";

export default NextAuth({
  providers: [
    EmailProvider({
      server: process.env.EMAIL_SERVER,
      from: process.env.EMAIL_FROM,
      maxAge: 10 * 60, // Magic links valid for 10 minutes
    }),
  ],
  adapter: MongoDBAdapter(clientPromise),
  pages: {
    signIn: '/auth/signin',
    verifyRequest: '/auth/verify-request',
  },
  callbacks: {
    async session({ session, user }) {
      session.user.id = user.id;
      return session;
    }
  }
});

• User experience benefits
  • No passwords to remember or manage
  • Reduced friction during signup/login
  • No password reset flows needed
  • Familiar email interaction pattern
  • Improved security (no password database)

Additional Connections

• Broader Context: Passwordless Authentication Methods (magic links as one approach)
• Applications: User Onboarding Optimization (reducing signup friction)
• See Also: Email Security (ensuring magic links aren't compromised)

References

1. OWASP Authentication Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html
2. Auth.js Documentation: https://authjs.dev/

#authentication #passwordless #security

Connections:

Sources:

• From: Marc Lou - Coding in 2025 is EASY (full roadmap to build ANY project from 0)