Piwik – Web analytics – Open source

piwik is an open source (GPL license) web analytics software. It gives interesting reports on your website visitors, your popular pages, the search engines keywords they used, the language they speak… and so much more. 

piwik aims to be an open source alternative to Google Analytics.

1. the features are built inside plugins: you can add new features and remove the ones you don’t need. If you are a developer, you can easily build your own plugins!
2. you own your data. Piwik being installed on your server, the data is stored in your own database and you can get all the statistics using open APIs (publishing the data in many formats: xml, json, php, csv)
3. (NOW AVAILABLE!!!) the user interface is fully customizable, you can drag and drop the widgets you want to display, create the reports you want