Best Open-source Identity & SSO tools

ZITADEL

Multi‑tenant identity platform delivering secure, self‑service authentication.

Better Auth

Comprehensive authentication and authorization library for TypeScript

Apereo CAS

Enterprise Single Sign-On and Identity Provider for Web

authentik

Open-source Identity Provider for modern SSO and authentication

Kanidm

Simple, secure identity management platform with everything built-in

Logto

Modern auth infrastructure for SaaS and AI apps

Stack Auth

Fast, developer-friendly authentication with built-in dashboard and RBAC

Keycloak

Open Source Identity and Access Management for Modern Applications

Authelia

Authentication and authorization server with SSO and 2FA

Casdoor

UI-first IAM and SSO platform with comprehensive protocol support

Hanko

Privacy-first, framework-agnostic authentication and user management platform

Ory Kratos

API‑first identity server for secure, scalable user management

Dex

Federated OpenID Connect identity service with pluggable connectors

Authlib

Spec-compliant Python library for OAuth and OpenID Connect

SuperTokens

Self‑hosted authentication platform delivering secure login and sessions.

Tesseral

Scalable API‑first auth platform for B2B SaaS

SSOReady

Add SAML and SCIM to any app in minutes

Vouch Proxy

Unified SSO gateway for Nginx using OAuth and OIDC