HAProxy is a

free and open source software Free and open-source software (FOSS) is software available under a Software license, license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term ...

that provides a

high availability High availability (HA) is a characteristic of a system that aims to ensure an agreed level of operational performance, usually uptime, for a higher than normal period. There is now more dependence on these systems as a result of modernization ...

load balancer and Proxy ( forward proxy, reverse proxy) for TCP and

HTTP HTTP (Hypertext Transfer Protocol) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, wher ...

-based applications that spreads 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

GoDaddy GoDaddy Inc. is an American publicly traded Internet Domain name registry, domain registry, Domain name registrar, domain registrar and web hosting company headquartered in Tempe, Arizona, and incorporated in Delaware. GoDaddy is the world's fif ...

GitHub GitHub () is a Proprietary software, proprietary developer platform that allows developers to create, store, manage, and share their code. It uses Git to provide distributed version control and GitHub itself provides access control, bug trackin ...

, Bitbucket,

Stack Overflow In software, a stack overflow occurs if the call stack pointer exceeds the stack bound. The call stack may consist of a limited amount of address space, often determined at the start of the program. The size of the call stack depends on many fa ...

Reddit Reddit ( ) is an American Proprietary software, proprietary social news news aggregator, aggregation and Internet forum, forum Social media, social media platform. Registered users (commonly referred to as "redditors") submit content to the ...

, Slack, Speedtest.net,

Tumblr Tumblr (pronounced "tumbler") is a microblogging and Social networking service, social networking website founded by David Karp in 2007 and is owned by American company Automattic. The service allows users to post multimedia and other content ...

Twitter Twitter, officially known as X since 2023, is an American microblogging and social networking service. It is one of the world's largest social media platforms and one of the most-visited websites. Users can share short text messages, image ...

and Tuenti and is used in the OpsWorks product from

Amazon Web Services Amazon Web Services, Inc. (AWS) is a subsidiary of Amazon.com, Amazon that provides Software as a service, on-demand cloud computing computing platform, platforms and Application programming interface, APIs to individuals, companies, and gover ...

History

HAProxy was written in 2000 by Willy Tarreau, a core contributor to the

Linux kernel The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...

, who still maintains the project. In 2013, the company HAProxy Technologies, LLC was created. The company provides a commercial offering, HAProxy Enterprise and appliance-based application-delivery controllers named ALOHA.

Features

HAProxy has the following features: * Layer 4 (TCP) and Layer 7 (HTTP) load balancing * Multi-factor stickiness * URL rewriting * Rate limiting * SSL/TLS termination proxy * Gzip compression * Caching * PROXY Protocol support * Scriptable multi-layer Health checking * Connection and HTTP message logging *

HTTP/2 HTTP/2 (originally named HTTP/2.0) is a major revision of the HTTP network protocol used by the World Wide Web. It was derived from the earlier experimental SPDY protocol, originally developed by Google. HTTP/2 was developed by the HTTP Working ...

support on both sides * HTTP/3 support *

WebSocket WebSocket is a computer communications protocol, providing a full-duplex, simultaneous two-way communication channel over a single Transmission Control Protocol (TCP) connection. The WebSocket protocol was standardized by the Internet Engineering ...

(RFC6455 and RFC8441) * UDP/TCP Syslog load-balancing and forwarding/transcribing (RFC3164 and RFC5424) * Event-driven Multithreaded architecture * Hitless reloads *

gRPC gRPC (acronym for gRPC Remote Procedure Calls) is a cross-platform high-performance remote procedure call (RPC) framework. gRPC was initially created by Google, but is open source and is used in many organizations. Use cases range from microservi ...

Support * Lua and SPOE Support *

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

Support * Layer 4/7 Retries * Simplified circuit breaking * Advanced debugging and tracing facilities * Distributed stick-tables for stats collection and DoS mitigation

HAProxy Community vs HAProxy Enterprise

HAProxy Enterprise Edition is an enterprise-class version of HAProxy that includes enterprise suite of add-ons, expert support, and professional services. It has some features backported from the HAProxy development branch.

ALOHA

HAProxy Technologies’ ALOHA is a plug-and-play load-balancing appliance that can be deployed in any environment. ALOHA provides a graphical interface and a templating system that can be used to deploy and configure the appliance.

Versions

HAProxy has had the following version releases:

Performance

Servers equipped with 6 to 8 cores generally achieve between 200,000 and 500,000 requests per second, and have no trouble saturating a 25 Gbit/s connection under Linux. 64-core ARM servers were shown to reach 2 million requests per second and 100 Gbit/s.

Similar software

Nginx (pronounced "engine x" , stylized as NGINX or nginx) is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache. The software was created by Russian developer Igor Sysoev and publicly released in 20 ...

* Gearman * Pound *

Varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmente ...

References

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External links

HAProxy Open Source Website

HAProxy Enterprise Website

HAProxy Wiki on GitHub

HAProxy issue tracker on GitHub
Free web server software Reverse proxy Proxy server software for Linux Free software programmed in C Unix network-related software Lua (programming language)-scriptable software