HAProxy

HAProxy is an open-source TCP/HTTP load balancer and proxy server. HAProxy terminates and proxies TCP connections to backend servers, and this can be used as HTTP reverse-proxy, TCP/HTTP normalizer, Layer-4 and Layer-7 (content-based) load balancer, traffic rate limiter, web application firewall, SSL termination point, etc. HAProxy monitors the health and load of individual backend servers for high availability and automatic failover. Its well-known high performance and scalability (e.g., 40 Gbps forwarding rate on an Intel Xeon E5 CPU core) come from various performance optimization techniques including single-threaded, event-driven, non-blocking network I/O, splice-based zero-copy forwarding, CPU affinity, efficient data structure for task queues, etc.