SlapOS

SlapOS (Simple Language for Accounting and Provisioning operating system) is a distributed, open source software platform for automating the deployment, accounting and billing of cloud computing services.

With SlapOS, anyone can become a cloud provider and sell Software as a Service (SaaS), Platform as a Service (PaaS) or Infrastructure as a Service (IaaS). The provider can use their own hardware infrastructure and/or public, shared infrastructure. 

A SlapOS cloud is composed of two components -- a SlapOS master and multiple SlapOS nodes. The SlapOS master is a representational state transfer (REST) web service that stores node configurations and assigns tasks to execute. The SlapOS nodes provide the actual computing resources required for the service.