authentik

authentik is an open-source Identity Provider designed for modern single sign-on and authentication workflows. It provides protocol support and configurable authentication flows to secure web, API, and remote-access use cases.

Key Features

• Supports standard identity protocols: OAuth2 / OIDC, SAML2, LDAP, RADIUS, SCIM and Kerberos for broad application compatibility
• Flexible multi-stage authentication flows, policy engine, and enrollment flows for MFA and conditional access (GeoIP, impossible-travel checks)
• MFA and modern second-factor support including TOTP and WebAuthn (passkeys)
• Application proxy / outpost model for protecting internal apps and enabling remote access (RDP, SSH, VNC) behind the IdP
• Rich admin, user, and flow interfaces plus REST APIs and SDKs for automation and integration
• Pluggable federation and social login sources, fine-grained policies, and templates for customizing login and enrollment behavior
• Deployment options and tooling for Docker Compose, Kubernetes (Helm), and cloud templates; background workers and channel layers for scale
• Caching and async task support via Redis; persistent storage and migrations for relational databases

Use Cases

• Enterprise replacement or augmentation of commercial IdPs to provide SSO, delegated access, and centralized authentication for web and API applications
• Protecting internal or home-lab applications using the outpost/application-proxy model to enforce authentication and authorization policies
• Integrating existing LDAP/AD directories and provisioning flows (SCIM) to enable consolidated identity management and MFA across services

Limitations and Considerations

• Some legacy native desktop or mobile clients that embed outdated browser engines may not support the full web-based login flow; a simplified flow executor (SFE) or alternate API-key approach may be required for such clients
• Major-version upgrades can require careful attention to migrations and worker restarts; administrators should test upgrades in staging before production rollouts

authentik provides a comprehensive, protocol-rich IdP with configurable flows and deployment flexibility. It is suited for organizations that need a self-hosted, extensible SSO solution with enterprise-grade features and automation capabilities.