HAProxy is a high-performance load balancer and proxy server for TCP and HTTP-based applications. It distributes incoming connections and requests across multiple backend servers, helping services maintain availability and responsiveness under heavy traffic.
The software is widely used as an entry point for websites, APIs and other network services. Its event-driven architecture is designed to handle large numbers of concurrent connections efficiently while providing detailed control over traffic distribution.
HAProxy combines load balancing with health monitoring, connection management and security policies. It also offers an integrated HTTP response cache for selected content, although caching is a secondary capability rather than the software’s primary purpose.
This is free and open source software.
Key Features
- Layer 4 and Layer 7 load balancing – distributes TCP connections and HTTP requests across backend servers.
- Multiple balancing algorithms – supports round-robin, least-connections, source hashing and other distribution methods.
- Backend health checks – detects unavailable servers and adjusts traffic routing automatically.
- HTTP response caching – stores eligible responses in shared memory using configurable cache filters.
- Cache policies – controls cache size, maximum object size, retention and conditional caching.
- High availability – supports redundant proxy configurations and graceful server maintenance.
- TLS termination – handles encrypted connections and certificate management.
- Access control lists – applies routing, security and traffic-handling rules based on request characteristics.
- Session persistence – keeps related requests associated with appropriate backend servers.
- Rate limiting – controls request rates and connection activity using stick tables and access policies.
- HTTP manipulation – modifies headers, redirects requests and rewrites selected traffic.
- PROXY protocol – forwards original client connection information between compatible network components.
- Connection management – provides configurable timeouts, retries and connection limits.
- Observability – exposes statistics, health information and detailed request logs.
- Runtime administration – supports operational changes through its administrative interface.
Website: www.haproxy.org
Support:
Developer: Willy Tarreau and contributors
License: GNU General Public License v2.0 with OpenSSL exception
HAProxy is written in C. Learn C with our recommended free books and free tutorials.
Related Software
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|---|---|
| Traefik | Modern HTTP reverse proxy and load balancer |
| HAProxy | High availability layer 7 load balancer and proxy server for TCP and HTTP |
| Cilium | eBPF-based Networking, Observability, Security |
| nginx | Includes a L7 load balancer |
| RoadRunner | High-performance PHP application server, load balancer, and process manager |
| fabio | Fast, modern, zero-conf load balancing HTTP(S) and TCP router |
| BFE | Modern L7 load balancer |
| Envoy | High-performance edge and service proxy built for cloud-native applications |
| APISIX | Real-time API gateway with routing, security and extensive plugin support |
| gobetween | Modern and minimalistic L4 load balancer and reverse-proxy |
| MetalLB | Adds external network service support to bare-metal Kubernetes clusters |
| Seesaw | Linux Virtual Server (LVS) based load balancing platform. L4 load balancer |
| Skipper | HTTP router and reverse proxy with flexible filters and route matching |
| LoxiLB | Cloud-native networking proxy with eBPF acceleration and observability |
| kube-vip | Provides virtual IPs and service networking across Kubernetes clusters |
| nuster | High-performance HTTP proxy cache server and HTTP/TCP load balancer |
| GLB Director | Set of stateless L4 load balancer servers |
| Balance | Generic TCP proxy with round robin load balancing and failover capabilities |
Read our verdict in the software roundup.
| Web Caches | |
|---|---|
| Vinyl | Web accelerator written with performance and flexibility in mind |
| HAProxy | High availability load balancer and proxy server |
| nginx | Very powerful and efficient web server and reverse proxy |
| Traffic Server | High-performance building block for cloud services |
| Squid | High-performance proxy caching server and web cache daemon |
| Envoy | High performance edge and service proxy |
| Apache APISIX | Dynamic API gateway with load balancing and traffic management |
| Apache | Hugely popular web server with caching modules |
| Souin | HTTP cache system |
Read our verdict in the software roundup.
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