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Original author(s) Willy Tarreau
Initial release December 16, 2001; 16 years ago (2001-12-16)
Stable release
1.8.0 / November 26, 2017; 6 months ago (2017-11-26)
Preview release
1.9-dev0 / November 26, 2017; 6 months ago (2017-11-26)
Repository Edit this at Wikidata
Written in C
Operating system Linux, FreeBSD, OpenBSD, Solaris (8/9/10), AIX (5.1–5.3)
License GNU General Public License Version 2
Website www.haproxy.org

HAProxy is free, open source software that provides a high availability load balancer and proxy server for TCP and HTTP-based applications that spreads requests across multiple servers.[1] It is written in C[2] and has a reputation for being fast and efficient (in terms of processor and memory usage).[3]

HAProxy is used by a number of high-profile websites including GoDaddy, GitHub, Bitbucket,[4] Stack Overflow,[5] Reddit, Speedtest.net, Tumblr, Twitter[6][7] and Tuenti[8] and is used in the OpsWorks product from Amazon Web Services.[9]


HAProxy was written in 2000[10] by Willy Tarreau,[11] a core contributor to the Linux kernel[12] who still maintains the project.


Servers equipped with a dual-core Opteron or Xeon processor generally achieve between 15000 and 40000 hits per second, and have no trouble saturating a 2 Gbit/sec connection under Linux.[13] Due to its widespread integration into enterprise-level infrastructures, monitoring HAProxy performance at scale has become an increasingly important issue. Monitoring end-to-end performance requires tracking metrics from frontends, backends, and HAProxy hosts themselves.[14] There are currently several tools available to track and monitor HAProxy performance, both open-source, like HATop as well as paid, like Datadog.

Similar software[edit]

See also[edit]


  1. ^ "MySQL Load Balancing with HAProxy". Severalnines AB. 2011. Retrieved 19 February 2013. 
  2. ^ "HAProxy on Freecode". Retrieved 5 April 2013. 
  3. ^ "Nuts & Bolts: HAproxy". Retrieved 8 April 2013. 
  4. ^ "The inner guts of Bitbucket". Retrieved 26 February 2015. 
  5. ^ "What it takes to run Stack Overflow". Retrieved 22 November 2013. 
  6. ^ "HAProxy: they use it!". Retrieved 5 April 2013. 
  7. ^ "List of sites using HAProxy". Archived from the original on 10 June 2013. Retrieved 5 April 2013. 
  8. ^ "Tuenti+WebRTC (Voip2day 2014)". 
  9. ^ "HAProxy layer - AWS Opsworks". Retrieved 5 April 2013. 
  10. ^ "HAProxy: design choices and history". Retrieved 5 April 2013. 
  11. ^ "Willy Tarreau: About me". Retrieved 5 April 2013. 
  12. ^ ,"LKML: Willy Tarreau: [ANNOUNCE] Linux". Retrieved 5 April 2013. 
  13. ^ haproxy.1wt.eu#plat
  14. ^ "Monitoring HAProxy Performance Metrics". Retrieved 17 Oct 2016. 

External links[edit]