Layer CSS - Lightweight CSS framework to build your own fluid layouts
UX Flow Wireframe Prototyping System - Create beautiful user flows prototypes for your next project
Paaatterns - Free collection of beautiful patterns for all vector formats
draw.io - Online diagramming application
Unused CSS - Easily find and remove unused CSS rules
UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.