HAProxy is a free, fast, and reliable reverse proxy and load balancer offering high availability, load balancing, and proxying for TCP and HTTP-based applications.
HAProxy solves the problem of distributing traffic across multiple backend servers while maintaining high performance and reliability. It operates as a reverse proxy that sits between clients and application servers, accepting incoming connections and routing them intelligently to available backends. The tool handles both TCP and HTTP protocols, supporting modern standards like HTTP/2 and TLS 1.3, and includes features for DDoS mitigation, caching, and FastCGI proxying.
HAProxy suits organizations running production systems that require robust load balancing and high availability. It is particularly valuable for teams managing multiple backend servers where traffic distribution, failover, and connection management are critical. The project provides extensive configuration documentation, a Lua scripting API for custom logic, and a Stream Processing Offload Engine (SPOE) for delegating complex processing tasks. The tool is suitable for both small deployments and large-scale infrastructure, with support for IPv6, proxy protocol, and network namespaces on Linux.
The project maintains active community engagement through discourse forums, mailing lists, Slack, and IRC channels dedicated to configuration assistance and questions. Development follows a structured branching model documented in the BRANCHES file to clarify version lifecycles and which versions users should adopt. The codebase includes a comprehensive regression testing suite that contributors can use to validate changes. Documentation is extensive, split across multiple files covering installation, configuration reference, Lua scripting, management, and internal architecture, with both text and HTML formats available.
