Authelia

Authelia is an open-source single sign-on and multi-factor authentication server that provides identity and access management for web applications behind reverse proxies. Released under the Apache 2.0 license and built in Go with a React frontend, the latest stable version is 4.39. The compressed container image is under 20 megabytes with observed runtime memory under 30 megabytes and sub-1-percent CPU utilization in small business environments, making it one of the most lightweight IAM solutions available. The login portal loads in under 100 milliseconds and authorization policies execute in single-digit milliseconds. As an OpenID Connect 1.0 Provider, the project holds OpenID Certified status, enabling standards-compliant integration with enterprise applications. Multi-factor authentication supports Time-based One-Time Passwords, WebAuthn security keys, mobile push notifications, and passwordless Passkeys. Single sign-on is delivered through OpenID Connect 1.0, session cookies, and trusted header injection for legacy applications. The platform integrates with LDAP and Active Directory for user directories, provides self-service password reset with email validation, and enforces brute-force protection with configurable lockout policies. Granular access control rules define per-domain, per-user, per-group authorization policies. Deployment is designed for high availability with horizontal scaling across Kubernetes clusters. Supported reverse proxies include Traefik, NGINX, Caddy, and HAProxy. The project is actively fundraising for a formal security audit and accreditation.