Authentik

Authentik is an identity provider you run yourself: OIDC, SAML, LDAP and proxy-based authentication for apps that have none, with customizable login flows, MFA and a modern admin UI. It has become the homelab favorite for putting one login in front of everything.

It is a real IdP with real complexity — Postgres and Redis underneath, and concepts (providers, applications, flows, stages) that reward reading the docs before clicking. Some enterprise features are paid, but the open-source core covers self-hosters completely.

Choose it when you are ready to graduate from per-app passwords to actual single sign-on.