Many large tech companies, such as Google and Meta, have historically developed their own internal tools rather than relying on widely available platforms like GitHub, driven by a "not invented here" mindset and the desire for complete control and seamless integration with their existing systems. While companies like Airbnb and Stripe have embraced SaaS tools including GitHub, leveraging the rich ecosystem available today, giants like Google have developed custom tools like Critique and Gerrit for code review, offering features tailored to their specific workflows. These internal tools provide sophisticated functionalities such as customizable dashboards, multi-level approval processes, and attention sets for managing code review tasks, which could theoretically be replicated on GitHub through its robust API and platform capabilities, albeit with a less polished user experience. The decision to develop in-house solutions often stems from the era of a company's founding and its cultural tendencies, raising questions about whether the largest companies will continue this trend as they scale or adapt to using more external tools as they grow.