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SecurityIntermediate ~14h

Authentication System

Tokens, sessions, refresh, and role-based access — done right.

Build a complete auth system from scratch. Email/password, OAuth, refresh tokens, sessions, password reset, email verification, role-based access, and the rate limits that keep it safe.

AuthSessionsRBACOAuthRate limits
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What you'll build

  • Email + password sign-in
  • OAuth (Google, GitHub) sign-in
  • Email verification + password reset
  • Access tokens + refresh tokens
  • Role-based access control
  • Rate limiting on sensitive routes

What you'll learn

  • Decide between sessions and tokens for your app
  • Implement refresh-token rotation correctly
  • Design a roles + permissions model that scales
  • Avoid the common auth security mistakes

Key flows

The end-to-end paths your data takes through the system.

Sign-in lifecycle

From form submit to authenticated session.

Submit
Verify password
Issue tokens
Set cookie
Authenticated

Refresh rotation

How a refresh token rotates safely.

Access expires
POST /refresh
Verify + rotate
New pair
Old refresh revoked

Build steps

A step-by-step path. Each milestone leaves you with a working slice.

  1. 1

    User model + password hashing

    Argon2/bcrypt, schema, basic sign-up.

  2. 2

    Sign-in + sessions

    Set cookie, validate on requests, sign-out.

  3. 3

    OAuth providers

    PKCE flow, account linking, profile sync.

  4. 4

    Tokens + refresh

    Access/refresh pair, rotation, revocation list.

  5. 5

    Email verification + password reset

    Single-use tokens, expiry, mail sending.

  6. 6

    RBAC + middleware

    Roles, permissions, route guards, audit log.

Read & study before you build

Related courses and articles that pair well with this project.