Black Friday and Cyber Monday have evolved into crucial global sales events, demanding extensive preparation from online retailers to manage the potentially overwhelming traffic surges. These peak shopping days require robust testing strategies to ensure seamless user experiences across websites and mobile applications, as technical failures during these busy periods can lead to significant revenue losses. Retailers must consider various factors, including load testing to simulate heavy traffic, cross-browser and cross-platform testing, synchronized browsing experiences, and the integration of multiple payment options. Effective preparation involves not only optimizing the technical infrastructure but also implementing efficient user experience practices, such as streamlined checkout processes and clear communication about product availability and discounts. As digital commerce continues to grow, particularly accelerated by the COVID-19 pandemic, these sales events offer a critical opportunity for businesses to expand their user base and increase revenue, highlighting the importance of meticulous testing and planning.