Pingendo : The simplest app for Bootstrap prototyping. Create quality HTML prototypes quickly, using popular open source tools like Bootstrap, LESS, Fontawesome ...
Pattern Tap : Organized Web Design Collection of User Interfaces for Inspiration and Ideas. The CSS Gallery Alternative
Modelio : Modelio is an open source modeling environment (UML2, BPMN2, ...). Based on a 20-year track record of high end commercial products, Modelio delivers a...
QtWeb Internet Browser : QtWeb is a fast, lightweight and portable browser with some unique UI and privacy features. QtWeb is an open source project based on Nokia's Qt framew...
Wireframing, mockups and prototyping for websites and applications