HAProxy is a free, open source high availability solution, providing load balancing and proxying for TCP and HTTP-based applications by spreading requests across multiple servers. It is written in C and has a reputation for being fast and efficient (in terms of processor and memory usage).HAProxy is used by a number of high-profile websites including GitHub, Bitbucket, Stack Overflow, Reddit, Tumblr, and Twitter and is used in the OpsWorks product from Amazon Web Services.