Stack Auth

Key Features of Stack Auth

• Open-source and self-hostable
  Licensed under MIT and AGPL, giving you full control and ownership over your user auth system.

• Plug-and-play UI components
  Includes <SignIn /> and <SignUp /> components with OAuth, password, and magic link support, all theme-aware.

• Headless SDK
  Use your own UI and logic with complete flexibility via our headless integration options.

• User dashboard & account settings
  Built-in management UIs so users can update profiles, reset passwords, and verify emails—no extra code required.

• Multi-tenancy and team support
  Support B2B apps with scalable organization structures, team roles, and user invitations.

• Role-based access control (RBAC)
  Define custom permission graphs and enforce access control per user or organization.

• OAuth token management
  Manage access to third-party APIs (like Google Calendar) with automatic token refresh handling.

• Passkeys and passwordless auth
  Support for biometric or hardware key-based authentication across devices.

• Impersonation
  Debug or support users by securely logging in as them.

• Webhooks and automation
  Trigger events (via Svix) when users sign up, log in, or take specific actions.

• Customizable email flows
  Send emails for verification, reset, and onboarding using a WYSIWYG editor.

• Machine-to-machine (M2M) auth
  Issue short-lived tokens for service-to-service communication.

• No JWT setup needed
  Tokens, cookies, and sessions are fully managed behind the scenes for optimal performance.

• REST and client APIs
  Use with any frontend or backend stack, thanks to a clean and consistent API design.

Meet Stack Auth: An Open-Source Alternative to Auth0 and Clerk

When building modern applications, user authentication is one of the first and most important challenges developers face. While platforms like Auth0 and Clerk offer convenient solutions, they often come with trade-offs: limited customization, rising costs, and a closed-source foundation. That's where Stack Auth steps in.

Stack Auth is a fully open-source, developer-first authentication platform built for flexibility, scale, and ease of use. Whether you're building a side project or scaling a SaaS business, Stack Auth provides everything you need—from login to advanced role-based access control—without locking you into a closed ecosystem.

Why Stack Auth?

Stack Auth is different because it puts developers first. You can spin it up in minutes, with official support for frameworks like Next.js and React, and a REST API that lets you plug into any backend. It's open-source under MIT and AGPL licenses, so you're free to host it yourself and even export your user data at any time. The managed service is optional—you're never locked in.

But it’s not just about authentication. Stack Auth also offers authorization, user management, teams, permissions, and secure OAuth integrations. It’s more than a login form—it’s the foundation for managing user identity across your app.

Auth That Feels Native to Your Stack

Stack Auth is built with modern React and Next.js in mind. It provides UI components like <SignIn /> and <SignUp /> that support dark/light themes, magic links, and third-party logins via OAuth. These components are beautifully styled and plug-and-play, but if you prefer full control, you can use the headless SDK and build your own interface.

On the backend, Stack Auth handles session management, access tokens, JWTs, and cookies for you. That means high performance without the headache of implementing it all yourself. Even machine-to-machine authentication is built-in, allowing short-lived tokens for your internal services.

Beyond the Basics

Unlike many authentication providers, Stack Auth doesn’t stop at login. You get a full user dashboard, ready out of the box, to search, filter, and manage users. There’s also a built-in settings UI for your users to update profiles, verify emails, or change passwords—no extra setup needed.

For more advanced scenarios, Stack Auth supports multi-tenancy, team management, and role-based access control. Want to allow one user to manage a team, while another only views their own data? It’s easy to model with organization-scoped roles and permission trees.

OAuth token handling is a breeze too. If your app connects to services like Google Calendar or Outlook, Stack Auth manages tokens, refreshes them automatically, and gives you simple API access without needing to write the plumbing yourself.

Built to Scale and Contribute

Stack Auth is designed for real-world usage, including impersonation for customer support, webhook integrations, passkey authentication, and customizable email templates. It’s built for teams who care about UX, security, and performance.

Developers are invited to contribute. Whether you want to extend features, fix bugs, or just understand how it all works, the codebase is approachable and well-documented. You’ll find guides, architecture overviews, and even ways to “chat with the codebase” to understand what’s happening under the hood.

Try It Yourself

Getting started takes just five minutes. You can deploy the managed service, or follow the self-hosting guide if you want full control. Either way, Stack Auth scales with your needs and adapts to your stack.

Authentication shouldn’t slow you down. With Stack Auth, it doesn’t.

---

Ready to build? Check out the docs or explore the GitHub repo to start integrating Stack Auth today.