Single-Sign-On (SSO) server with multiple factor authentication.

Authentication processes supported:

* OAuth2
* OpenID Connect
* Allows users to authenticate via multiple factors:

Password
* One-time password (TOTP/HOTP)
* Webauthn (Yubikey, Android devices)
* One-time password sent via e-mail
* TLS Certificate
* Users and clients can be stored and managed from various backends:

Database
* LDAP service
* HTTP Backend service providing Basic Authentication