Mozilla is celebrating the one billionth download of its Firefox web browser.

Mozilla, the firm behind the open source browser, has set up a website to mark the occasion called One Billion Plus You and was counting down to the one billionth download via Twitter and its Spread Firefox website.

The first version of Firefox was launched in November 2004 and June 2009 saw the release of version 3.5, the most up-to-date version. In June 2008 version 3 of Firefox set a new world record when it was downloaded eight million times in a 24-hour period.

Since its launch the browser has seen a steady climb in user numbers and now claims a market share of around 30%, placing it second behind market leader Internet Explorer on 60%. Apple’s Safari browser is in third with Google Chrome in fourth.

With Microsoft removing its Internet Explorer as the default browser on Windows machines in the EU, Firefox can confidently expect its market share to grow.

Mozilla is currently working on version 4 of the browser.