“HAProxy Load Balancer is highly configurable, rock solid with excellent support and is faster than NGINX in our setup.”

“HAProxy is used heavily at Github and we couldn’t do a lot of what we do without it.”
– Matt at GitHub.

The GitHub Blog entitled « How We Made GitHub Fast ». It explains in depth how the GitHub architecture works, and there’s a lot to learn there for anyone who’s planning on starting a scalable site. Interestingly, a second article here gives a few more details as to why they’re not only using HAProxy but ldirectord too (e.g. smaller memory usage in VMs).

Mike Krieger explains on Slideshare how Instagram scaled to more than 30 million users in less than 2 years with the help of HAProxy.

“We’re big fans of HAProxy, which the guys at Reddit turned us on to. It has been working flawlessly for us in load balancing Stack Overflow between two – and now three – servers.”

See their presentation on the updated architecture

“HAProxy: Kick-ass load balancing software.” 

MaxCDN has a blog presentation here explaining how they’re using HAProxy.

This article gives some details on the Tumblr architecture that supports 500M page views a day, 40k requests/s with plans to go to 400k, and observes a 30% monthly growth. It involves more than 1000 servers, and employs 25 HAProxy, 15 Varnish and 8 nginx to make this run smoothly.

“HAProxy is a pretty magical piece of software that we use extensively at Twilio.”

“The HAProxy maintainer, Willy Tarreau, was a real pleasure to work with. He recognized the value of the algorithm, and didn’t tell me how terrible my patch was. He did a thorough review and provided some very valuable feedback.”

“One of the important lessons we’ve taken away is that simple approaches are often the right ones. This system has been working for us reliably for more than a year without any incidents. Stripe doesn’t process anywhere near as many requests as Twitter or Facebook, but we do care a very great deal about extreme reliability.

See their HAProxy configuration here.

As described in their architecture overview, Red Hat uses HAProxy as the load balancing solution in its cloud architecture OpenShift. While I know for sure they’re not the first cloud provider to use it, I can say that they’re the first one to openly admit it and that’s nice from them (their architecture overview is well detailed and worth a read BTW).

“The real work is performed by HAProxy, which is extremely stable and battle-tested…Using HAProxy gives us a whole host of advantages. We get all of the powerful logging and introspection. We get access to very advanced load-balancing algorithms, queueing controls, retries, and timeouts. There is built-in health checking which we can use to guard against network partitions (where we learn about an available backend from Nerve, but can’t actually talk to it because of the network). In fact, we could probably fill an entire additional blog post just raving about HAProxy and how we configure it.”

Airbnb built SmartStack on top of HAProxy. The article explains in details the limitations of all other solutions they have considered (including HAProxy itself).

Taobao’s CDN is the world’s largest picture CDN, it delivers contents for all online shops hosted by Taobao and Alibaba, they represent around 80% of China’s online business. They use simple and scalable architecture including LVS + HAProxy for the load balancing layer, Squid for the cache and their fork of nginx (Tengine) for the servers. A fairly complete and interesting overview is available here.

Disqus chose HAProxy because it offers “high performance, intelligent server availability checking and nice statistics reporting”.

An article on High Scalability gives some details about the architecture behind DISQUS and the traffic it has to deal with:. 17000 requests per second, 250 million visitors. They’re using HAProxy both in front of the web servers and in front of the database. See the detailed presentation.

“HAProxy is a fantastic feature-rich load balancer and we at Egnyte have been using it for a while. Apart from using HAProxy for standard application load balancing, we are using HAProxy to overcome some limitations of Apache like use queue timeout to prevent backlogging in Apache when application servers are loaded. We also use HAProxy for load direction to route requests i.e. send requests to specific server under specific conditions and failover accordingly.”

Fedora is the community-driven distribution behind Red Hat. The Wiki explains how HAProxy is used there, and even provides links to the stats pages.

Virgin America uses HAProxy for load balancing. See a complete presentation from LinuxCon 2010 where they explain their usage of it.  It’s available in PDF format here.

“W3C’s main web site www.w3.org is load-balanced over a number of servers using the excellent HAProxy load balancing software.”

See more information on how W3C uses HAProxy here.

“We use HAProxy in four different EC2 regions and five Availability Zones. It allows us to handle over 10 billion HTTP bid requests a day and deliver over six billion videos ad streams last year”.

Linux Kernel hosting infrastructure’s admin and architect, Konstantin Ryabitsev, shares his experience running one of the most challenging sites dedicated to development, and of course it runs behind HAProxy 🙂

“HAProxy is part of an architecture that scales to 1,000,000 concurrent users” 

See architecture description on slideshare

Alan from Imgur describes his architecture choices on Reddit here and why HAProxy makes a good choice for him here.

“We know that using HAProxy allows us to build robust and scalable setups not only for our clients, but for our internal services as well. We operate multiple internal or private cloud Infrastructures where the management layer’s high availability and scalability is done with HAProxy. HAProxy is a reliable constant in our clustering design.”

Globo.Tech is a Hosting and Managed Service Provider, in Canada.

“Biblio.com uses HAProxy to load balance and provide fault tolerance for 10 million searches per day across a cluster of Solr search servers that index 95 million bibliographic records of used and rare books. HAProxy has been very fast and rock solid for us. Thanks for providing it.”

“Very robust and reliable, layer 7 load balancing.  HAProxy was designed to be a load balancer.”  

Spanish website with more than 12M users and 40 billion page views a month.  
http://www.slideshare.net/ricbartm/load-balancing-at-tuenti.

“We use HAProxy extensively, both as a standard edge load balancer and (especially in AWS) as a proxy for internal services, avoiding the need for IP-based failover.”

BitPusher designs, implements and manages infrastructures that are highly reliable, scalable and performant.

“A0 Labs is a French hosting company specialized in critical applications which need high performance and security. We have been using HAProxy for several years now and deploy it for our customers to provide high availability and performance to their web sites.”

Free is a major player among the french ISPs. Free has always promoted the use of free software, and has been using HAProxy for years. The Webmail and the file exchange service have been the most heavily loaded deployment ever reported in terms of network bandwidth, with more than 5 Gbps of traffic at any moment with over 10Gbps performance possible.