If you're searching for an open source alternative to Clerk, you're in the right place.
This page highlights standout tools that give you full control over auth, from simple logins to enterprise-grade identity management.
No vendor lock-in. No hidden costs. Just powerful, transparent authentication systems you can run on your own terms.
Keycloak
A battle-tested open source IAM solution.
Built with enterprise needs in mind, Keycloak centralizes user management, authentication, and authorization.
Supports SSO, social login, LDAP/AD integration, and federated identity providers via OIDC and SAML.
Everything is managed through a powerful admin console, while users enjoy a self-service portal for profiles and 2FA.
Highly customizable, scalable, and compliant with standards like OAuth2, OIDC, and SAML.
Offers fine-grained authorization, making it ideal for complex access control requirements.
Auth.js (formerly NextAuth.js)
Modular, open source authentication for modern JavaScript runtimes.
Framework-agnostic and runtime-flexible, it works with Node, edge functions, Docker, and more.
Provides OAuth, email, WebAuthn, LDAP, and JWT support out of the box.
Sessions sync across tabs and windows, with full TypeScript support and strong security defaults.
You stay in control — Auth.js is designed for full data ownership and extensibility.
Authentik
A self-hosted identity provider focused on flexibility and control.
Implements protocols like OAuth2, SAML, OIDC, LDAP, and RADIUS.
Perfect for replacing commercial IdPs such as Okta or Auth0.
Customizable login flows, delegated user management, MFA, adaptive policies, and Zero Trust-ready.
Fits into modern DevOps pipelines with IaC support and API-based automation.
Supertokens
Developer-first auth that’s easy to integrate and easy to own.
Provides frontend components, backend SDKs, and a self-hosted auth core.
Supports email/password, passwordless, social login, MFA, and RBAC.
Great for microservices, mobile apps, and multi-tenant platforms.
Open source with optional managed hosting — you choose the stack and control the system.
Better Auth
An auth library built specifically for TypeScript ecosystems.
Lightweight, framework-agnostic, and easy to extend.
Out of the box support for 2FA, social login, multi-tenancy, and email/password flows.
Designed to cut boilerplate and eliminate the need to duct-tape libraries together.
A plugin system adds advanced capabilities without complexity.
Zitadel
A modern identity platform with built-in multi-tenancy.
Supports passkeys, OTP, OAuth2, OIDC, SAML2, LDAP, and enterprise SSO.
API-first and built with event sourcing, it scales to meet enterprise requirements.
Organizations can customize branding, manage roles, and integrate deeply using Actions (event hooks).
PostgreSQL-powered and available as both open source and hosted.
Logto
Flexible identity for modern apps with full developer control.
Comes with a web admin console and polished authentication flows (including Google One Tap and dark mode).
API-first, with support for OAuth2, OIDC, SAML, and social logins.
Built-in multi-tenancy, MFA, impersonation, and RBAC make it SaaS-friendly.
Easy to integrate with SDKs for over 30 frameworks, including CLI tools and web apps.
Hanko
Authentication for the passkey era.
Fully open source, API-first, and built for cloud-native apps.
Focuses on passwordless login by default, with support for passkeys, social auth, and fallback methods.
Includes customizable web components that work with any frontend stack.
Perfect for teams embracing modern UX and progressive security patterns.
Stack Auth
Stack Auth is an open-source authentication platform built for developers who want full control without compromising on modern features. It supports passkeys, magic links, social logins, and traditional email/password — all with a flexible, framework-agnostic API. Easily integrate into stacks like Next.js, Remix, or SvelteKit and deploy on your own infrastructure. No lock-in. All control. Built for the modern web.