Late 1990s

The Xen hypervisor was first created by Keir Fraser and Ian Pratt as part of the Xenoserver research project at Cambridge University in the late 1990s. A hypervisor "forms the core of each Xenoserver node, providing the resource management, accounting and auditing that we require." The earliest web page dedicated to the Xen hypervisor is still available on Cambridge web servers.  The early Xen history can easily be traced through a variety of academic papers from Cambridge University. Controlling the XenoServer Open Platform is an excellent place to begin in understanding the origins of the Xen hypervisor and the XenoServer project. Other relevant research papers can be found at:

Over the years, the Xen community has hosted several Xen Summit events where the global development community meets to discuss all things Xen. Many presentations and videos of those events are available here.


The Xen hypervisor was open sourced to allow a global community of developers to contribute and improve the product.


The first public release of Xen is announced at the USENIX Operating Systems Design and Implementation conference in the fall.  We regard this as the "birthday" of Xen.


Xen 1.0 was officially released followed a short time later by Xen 2.0. At the same time, Ian Pratt and several other technology leaders founded XenSource, Inc. to convert the Xen hypervisor from a research tool into a competitive product for enterprise computing. As part of the corporate strategy, the Xen hypervisor remained an open source solution.


Widespread adoption of the Xen hypervisor took place when Red Hat, Novell, and Sun all added the Xen hypervisor as their virtualization solution of choice. The development community also accelereted the capabilities of Xen with the Xen 3.0 release.


Microsoft and VMWare adopted the concept of Paravirtualization, first introduced by the Xen community.


Citrix Systems, Inc. acquired XenServer in August for $500 million.
“This announcement represents a key milestone for the Xen project,” said Ian Pratt, leader of the Xen project and co-founder of XenSource. “Citrix is committed to our community and the principles of transparency and neutrality that allow us to work together on the reference standard for virtualization, promoting the rapid, ubiquitous adoption of virtualization.”


The Xen ARM project is created by Samsung Electronics.


The Xen community announced a new initative for Cloud Computing, Xen Cloud Platform.


The Xen community releases Xen 4.0.  In early 2010, a community contest was held to create the Xen mascot. The official mascot was launched in June 2010.


Linux 2.6.37, is the first upstream Linux kernel that canboot on Xen as Dom0 out-of-the-box.

The Xen community delivered the first version of the Xen Cloud Platform.

Linux 3.x, contains full support for Xen Dom0 and DomU. Major Linux distributions announce that they will re-introduce Xen into their distributions.

Project Kronos is created to deliver XCP supporting Debian and Ubuntu as Dom0, as well is being distributed via Linux distributions.

First Xen prototype for XenARM using Cortex A15 is announced.


The Xen Cloud Platform packages for Linux are released.


The Xen ARM port becomes functional.

Xen becomes part of the Linux Foundation as a Linux Foundation Collaborative Project.  The community website is transitioned from Xen.org to a more modern website at XenProject.org, and the new trademark "Xen Project" is issued to the Linux Foundation.

The first truly user-centric event is held, called the Xen Project User Summit.


The number of Advisory Board members expands.

Mirage OS 2.0 is released.