FontViz is highly praised by users, particularly UI/UX designers and developers, for its ability to simplify font inspection on web apps. Users appreciate its one-click functionality, which provides instant typography details, making it a valuable tool for speeding up design processes and enhancing workflow efficiency. The tool is described as intuitive and effective, allowing for easy font editing and real-time previews. Many users highlight its usefulness in both design and development contexts, emphasizing its role in streamlining tasks that were previously time-consuming.