Lan Core is a free & open source software that lets you to build a thin client network on a Windows operating system. It was originally designed to work in a server or workstation with Windows XP Professional using the native remote desktop protocol.
Minirighi is a multi-threading open-source operating system written for didactic purpose. It has been written from scratch and it is compatible with POSIX.
SWAL is a program that can launch as a service (or standalone) and monitor other services and control other programs. Written in C++ and might have some .NET components (planning on a linux port)
Unlimited organizations, 3 enterprise SSO connections, role-based access control, and pro MFA included. Dev and prod tenants out of the box.
Auth0's B2B Essentials plan gives you everything you need to ship secure multi-tenant apps. Unlimited orgs, enterprise SSO, RBAC, audit log streaming, and higher auth and API limits included. Add on M2M tokens, enterprise MFA, or additional SSO connections as you scale.