HA Proxy 1.4 : From the Ground Up

HAProxy, written in C by Willy Tarreau, is open source software for TCP and HTTP load balancing. It’s known for stability, efficiency and speed; chances are that this reputation is why you are installing it.

Load balancing, though, is a term that covers a broad range of functions, from basic TCP tunneling at Layer 4 to reverse proxy at Layer 7, and you may find more functionality in HAProxy than you expected—or, more than you bargained for.