UserBit helps to understand user needs, manage interview notes, synthesize data, create personas, visual sitemaps and more.
UserTesters connect startups with suitable test candidates to test apps and websites for a little bit of cash.
They have all kinds of diagramms and charts ready to customize or you just start creating your own from scratch for free.
Super simple tool to create wireframes, flowcharts, sticky notes and mindmaps and then collaborate on them.
Most comprehensive but also expensive high fidelity wireframe and prototyping tool used by professionals.