Fluid UI is a browser-based wireframing and prototyping tool developed by Fluid Software and used to design mobile touch interfaces.
License: Freemium
Gliffy is primarily focused on diagramming and offers a user-friendly interface with a strong emphasis on collaboration, making it ideal for teams. In contrast, Fluid UI specializes in interactive prototyping, providing comprehensive design tools for web and mobile projects, though it may require more time to learn.