Comprehensive Web App Testing

I need a website and web app tester to conduct a thorough quality review of our codes and application use cases. The testing should focus on functionality, usability, and performance across desktop and mobile devices, specifically on Windows OS.

Ideal skills and experience:
- Expertise in testing web applications
- Strong understanding of usability and performance metrics
- Experience with cross-platform testing on Windows
- Ability to document findings and suggest improvements

Looking for detail-oriented professionals who can ensure a seamless user experience.