Axure - The most powerful way to plan, prototype and hand off to developers, all without code. Download a free trial and see why professionals choose Axure RP 9.
ANTS Performance Profiler - Speed up the performance of your application with ANTS Performance Profiler, for .NET code analysis.
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Telerik - UI Frameworks and App Development Tools
Moqups - The most stunning HTML5 app for creating resolution-independent SVG mockups, wireframes & interactive prototypes for your next project
dotTrace - dotTrace helps you detect performance bottlenecks in a variety of .NET and .NET Core applications