- Database: Oracle, MySQL, PostgreSQL - OS: Linux, Windows, Mac OS X; - Java Core: Java Core, Multithreading, Collections API, etc; - Frameworks: Eclipse RCP, JUnit; - Core web: XML, JSON, HTML/CSS, JavaScript; - CMS: Joomla, Drupal. - IDE: Eclipse; - Bug/Issue trackers: Jira, Assembla, Redmine; - UML.