UI Critic by Usercall is an AI-powered tool that provides synthetic user testing for design screenshots. Users can upload 1-3 screenshots and receive annotated critiques that identify hidden user assumptions and potential risks in their UI designs.

The tool generates annotated feedback directly on uploaded screenshots, allowing designers to see specific areas of concern. It provides synthetic or simulated user feedback without requiring real human testers, making the process faster and more accessible.

The system works by analyzing uploaded screenshots and automatically identifying design elements that may create confusion or usability issues. It pins annotations directly onto the images to highlight specific problems and assumptions embedded in the design.

This approach helps designers catch potential issues before shipping their products, reducing the risk of user confusion or poor experiences. It serves as an early warning system for UX problems that might otherwise go unnoticed until real users encounter them.

The tool targets designers and product teams who need quick feedback on their UI designs without the time and cost of traditional user testing. It's particularly useful for rapid iteration cycles where immediate feedback is valuable.