Effective quality assurance (QA) is pivotal to building scalable web services, particularly in high-demand environments like streaming platforms. This talk explores advanced strategies in QA, drawing insights from the work done at Netflix, where the Growth Engineering team implemented vital system advancements to combat challenges in customer security and accessibility. Focusing on two critical initiatives—integrating multi-factor authentication (MFA) to protect user accounts and introducing scalable systems to support new business models in emerging markets—we'll delve into the technical complexities and QA strategies employed. These projects required cross-functional collaboration, robust testing frameworks, and the development of a resilient backend architecture. Technologies such as Java, Spring, GRPC, and AWS played a crucial role, alongside testing tools like Junit and EasyMock, ensuring both the robustness and scalability of the solutions. Attendees will gain insights into the QA methodologies used to maintain quality standards amidst rapid feature releases. This talk will highlight key takeaways, such as the importance of early-stage QA involvement in product design, the role of advanced automation in reducing regression risk, and effective collaboration techniques across product, data science, and engineering teams. By attending this session, participants will learn practical approaches for enhancing QA processes in complex, large-scale projects. Whether you are sharpening your QA skills or driving innovation in quality standards, this talk will offer valuable strategies to refine your QA practices and ensure seamless deployment of global services.