Arora : Arora is a lightweight cross-platform web browser. It's free (as in free speech and free beer). Arora runs on Linux, embedded Linux, FreeBSD, Mac OS X...
ClickHeat : ClickHeat is a visual heatmap of clicks on a HTML page, showing hot and cold click zones. ClickHeat is an OpenSource software, released under GPL lice...
Pattern Tap : Organized Web Design Collection of User Interfaces for Inspiration and Ideas. The CSS Gallery Alternative
Pingendo : The simplest app for Bootstrap prototyping. Create quality HTML prototypes quickly, using popular open source tools like Bootstrap, LESS, Fontawesome ...
Inkscape : Inkscape is a professional vector graphics editor for Windows, Mac OS X and Linux. It's free and open source.
Wireframing, mockups and prototyping for websites and applications