Open source software has provided the foundation for many cloud computing implementations: - OpenNebula is an open-source toolkit to easily build any type of cloud: private, public and hybrid. OpenNebula has been designed to be integrated with any networking and storage solution and so to fit into any existing data center. OpenNebula orchestrates storage, network and virtualization technologies to enable the dynamic placement of multi-tier services (groups of interconnected virtual machines) on distributed infrastructures, combining both data center resources and remote cloud resources, according to allocation policies. - Eucalyptus began as a research project in the field of high performance computing (HPC) under the direction of Professor Rich Wolski in the Computer Science Department at the University of California, Santa Barbara. Eucalyptus is an open-source software infrastructure for the implementation of cloud computing on computer clusters which provides an interface that is compatible with the Amazon EC2 service. It is also the core element of the Ubuntu Enterprise Cloud (UEC), a cloud computing module provided with distributions of the Linux-based Ubuntu operating system. - Tashi is an open-source project being incubated at Apache that aims to build a software infrastructure for cloud computing on massive internet-scale datasets (a.k.a. 'Big Data'). The idea is to build a cluster management system that enables the Big Data that are stored in a cluster/data center to be accessed, shared, manipulated, and computed on by remote users in a convenient, efficient, and safe manner. Tashi is primarily a system for managing virtual machines. In this presentation, I'll start talking about some of the basic concepts related to Cloud Computing and Virtualization. After that, I'll present the three tools, showing their Cloud API and main features. A brief comparison among the tools and install procedures will also be presented.