Piwik is a free and open source web analytics software written by a team of international developers that runs on a PHP/MySQL webserver. It tracks online visits to one or more websites and displays reports on these visits for analysis. As of September 2015, Piwik was used by nearly 900 thousand websites, or 1.3% of all websites, and has been translated to more than 45 languages. New versions are regularly released every few weeks. More: en.wikipedia.org.