The new, recently unveiled, web site of gov.uk is almost entirely built on or with open source.
It is hosted on a server running Ubuntu 10.04LTS, with Jetty as the application server and Nginx, Apache and mod_passenger as the HTTP servers. Jenkins provides a continuous integration service, Varnish provides the caching whilst the configuration management is organised by Puppet.
The website code is mostly written in Ruby, with either Rails or Sinatra providing the framework; the developers have organised a github repository with the gems they have created and used for the website. Developers began building the system with MySQL but have been moving over to MongoDB as they "realised how much of our content fitted its document-centric approach". For geocoding, the developers use MySociety.org's MaPit.
In an earlier blog posting by the project leader, Tom Loosemore, it was described how the developers aim to "deliver simpler, clearer, faster services for users and savings and innovation for Government". Gov.uk is destined to replace the DirectGov web site and the designers have taken 667 of the things citizens need from government, based roughly on what DirectGov handles, and reformed them to be more "findable, understandable and actionable".
The budget for the beta gov.uk site is £1.7 million which the project says it is currently running under.