A developer built an interactive system design reference site that lets you view the same architecture through AWS, Google Cloud, Azure, or open-source tooling. It covers 36 systems, 36 components, and 27 concepts, with auto-laid-out diagrams you can step through hop by hop. Each system page includes requirements, APIs, capacity estimates, data models, bottlenecks, and scaling notes. The site is built with Next.js static export deployed on Vercel, React Flow plus ELK for diagrams, Tailwind CSS, and Zod for schema validation, and it's open source on GitHub.