HAProxy

HAProxy is a free and open source software that provides a high availability load balancer and Proxy (forward proxy,^[2] reverse proxy) for TCP and HTTP-based applications that spreads requests across multiple servers.^[3] It is written in C^[4] and has a reputation for being fast and efficient (in terms of processor and memory usage).^[5]

Original author(s)	Willy Tarreau
Initial release	December 16, 2001; 23 years ago (2001-12-16)
Stable release	3.1.0[1]  / 26 November 2024
Repository	github.com/haproxy/haproxy/
Written in	C
Operating system	Linux, FreeBSD, OpenBSD, Solaris (8/9/10), AIX (5.1–5.3), macOS, Cygwin
License	GNU General Public License Version 2
Website	www.haproxy.org

HAProxy is used by a number of high-profile websites including GoDaddy, GitHub, Bitbucket,^[6] Stack Overflow,^[7] Reddit, Slack,^[8] Speedtest.net, Tumblr, Twitter^[9][10] and Tuenti^[11] and is used in the OpsWorks product from Amazon Web Services.^[12]

History

HAProxy was written in 2000^[13] by Willy Tarreau,^[14] a core contributor to the Linux kernel,^[15] who still maintains the project.

In 2013, the company HAProxy Technologies, LLC was created.^{[citation needed]} 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^[16] support on both sides
• HTTP/3^[17] support
• WebSocket (RFC6455 and RFC8441)
• UDP/TCP Syslog load-balancing and forwarding/transcribing (RFC3164 and RFC5424)
• Event-driven Multithreaded architecture
• Hitless reloads^[18]
• gRPC Support^[19]
• Lua and SPOE Support
• API 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.^[20]

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.^[21]

Versions

HAProxy has had the following version releases:^[22]

Version	Release date	End of life
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.0" | Old version, not maintained: 1.0	2001-12-16	2001-12-30
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.1" | Old version, not maintained: 1.1	2002-03-10	2006-01-29
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.2" | Old version, not maintained: 1.2	2003-11-09	2011-08-06
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.3" | Old version, not maintained: 1.3	2006-06-29	2016-03-14
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.4" | Old version, not maintained: 1.4	2010-02-26	2018-02-08
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.5" | Old version, not maintained: 1.5	2014-06-19	2020-01-10
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.6" | Old version, not maintained: 1.6	2015-10-13	2020-Q4
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.7" | Old version, not maintained: 1.7	2016-11-25	2021-Q4
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.8" | Old version, not maintained: 1.8	2017-11-26	2022-Q4
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="1.9" | Old version, not maintained: 1.9	2018-12-19	2020-Q2
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="2.0" | Old version, not maintained: 2.0	2019-06-16	2024-Q2
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="2.1" | Old version, not maintained: 2.1	2019-11-25	2021-Q1
class="templateVersion co swatch-maintained" style="color: var(--color-base, #202122); " title="Old version, still maintained" data-sort-value="2.2 LTS" | Old version, still maintained: 2.2 LTS	2020-07-07	2025-Q2 (critical fixes only)
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="2.3" | Old version, not maintained: 2.3	2020-11-05	2022-Q1
class="templateVersion co swatch-maintained" style="color: var(--color-base, #202122); " title="Old version, still maintained" data-sort-value="2.4 LTS" | Old version, still maintained: 2.4 LTS	2021-05-14	2026-Q2 (critical fixes only)
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="2.5" | Old version, not maintained: 2.5	2021-11-23	2023-Q1
class="templateVersion co swatch-maintained" style="color: var(--color-base, #202122); " title="Old version, still maintained" data-sort-value="2.6 LTS" | Old version, still maintained: 2.6 LTS	2022-05-31	2027-Q2
class="templateVersion co swatch-unsupported" style="color: var(--color-base, #202122); " title="Old version, not maintained" data-sort-value="2.7" | Old version, not maintained: 2.7	2022-12-01	2024-Q1
class="templateVersion co swatch-maintained" style="color: var(--color-base, #202122); " title="Old version, still maintained" data-sort-value="2.8 LTS" | Old version, still maintained: 2.8 LTS	2023-05-31	2028-Q2
class="templateVersion co swatch-maintained" style="color: var(--color-base, #202122); " title="Old version, still maintained" data-sort-value="2.9" | Old version, still maintained: 2.9	2023-12-05	2025-Q1
class="templateVersion co swatch-maintained" style="color: var(--color-base, #202122); " title="Old version, still maintained" data-sort-value="3.0 LTS" | Old version, still maintained: 3.0 LTS	2024-05-29	2029-Q2
class="templateVersion c swatch-latest" style="color: var(--color-base, #202122); " title="Latest version" data-sort-value="3.1" | Latest version: 3.1	2024-11-26	2026-Q1
Legend: Old version, not maintained Old version, still maintained Latest version Latest preview version Future version

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.^[23] 64-core ARM servers were shown to reach 2 million requests per second and 100 Gbit/s.^[24]

Similar software

• Nginx
• Gearman
• Pound
• Varnish

See also

• Free and open-source software portal

• LAMP, LYME, and LEAP