Undesign - Free design tools and resources for your projects
FeaturePeek - Collaborate on in-progress website implementations. FeaturePeek allows your team to collect feedback on your front-end during the implementation phase of development.
Super designer - Super designer is a collections of simple design tools to create unique designs in a a few clicks.
Atomic - The fastest way to design beautiful interactions
Lean Service Creation - Open source design process and toolkit
The Ultimate Design Tool Picker - Find the best design tool for your use case