KDevelop is a Free and Open Source integrated development environment (IDE).
It provides editing, navigation and debugging features for several programming languages, as well as integration with multiple build systems and version-control systems, using a plugin-based architecture.
PHP language support for KDevelop
Python language support for KDevelop
Qt Designer UI File Viewer in KParts-using software
Rendered display of Markdown files in KParts-using software (webtech-based)
Rendered display of Markdown files in KParts-using software
Rendered display of SVG files in KParts-using software