HAProxy

High Availability Proxy — a free, open-source, high-performance TCP and HTTP load balancer and proxy server widely used in production infrastructure. HAProxy operates in either TCP mode (Layer 4) or HTTP mode (Layer 7) and supports advanced features including ACL-based routing, health checks, connection draining, rate limiting, SSL/TLS termination, PROXY Protocol, server-side keep-alives, and detailed statistics via a built-in web dashboard. It is used by large internet platforms such as GitHub, Airbnb, and Tumblr and forms the backbone of many Kubernetes ingress controllers and PaaS platforms.