authentik is an open-source Identity Provider focused on flexibility and versatility. You can use authentik in an existing environment to add support for new protocols, implement sign-up/recovery/etc. in your application so you don't have to deal with it, and many other things.
Open source password management solutions for individuals, teams, and business organizations.
Nextcloud is an open source, self-hosted file share and communication platform. Access and sync your files, contacts, calendars and communicate and collaborate across your devices.