The site is being served by nginx. nginx is a popular open-source web server software that can be used to serve static websites and dynamic websites in high performance. It is also known for its ability to handle large volumes of traffic and provide high uptime. Many websites use nginx as their primary web server, due to its reliability and scalability. nginx supports various protocols including HTTP, HTTPS, and gRPC, making it a versatile option for serving web applications. The site's inability to serve the requested file is likely due to nginx being configured to prevent access or the request being blocked by security measures.