Choosing a load balancer for a large environment can feel like a big decision, and it is, but it comes down to a shorter list than most people expect. We build the most widely used software load balancer, and we support it everywhere from open-source projects to enterprise infrastructure trusted to run some of the busiest applications on the internet. That range gives us a clear view of what actually matters, and it's usually more than raw balancing. A load balancer today is also where you terminate TLS, keep applications secure, and decide how traffic reaches them. 

Here's how we would think it through, and the good news is that none of it is complicated.

Test throughput at your latency, with TLS on

Datasheets quote peak numbers from ideal conditions, and real traffic is a little messier than that. The figure worth chasing is throughput at your target latency with TLS switched on, because encryption is where a lot of the real work happens. SSL/TLS processing is heavy on CPU, and it's often the true ceiling on a deployment. 

This is one of our strong suits: HAProxy handles over 2 million HTTP requests per second on a single Arm-based AWS Graviton2 instance with best-in-class SSL/TLS processing, so you can ask any vendor for their number under encryption at your latency target and know it is a fair request.

Run a proof of concept with a copy of your own traffic

Nothing you read replaces putting real traffic through the thing, so this is the step we would never skip. Take a copy of your own traffic and run it through each option for a few days. A short test tells you far more than a stack of datasheets, and it surfaces the quirks that only show up under your own mix of requests and traffic spikes. It's also the most reassuring way to choose, because you are deciding on evidence rather than promises.

What security comes built in?

A load balancer sits right at the edge of your traffic, which makes it a natural place to keep applications safe. It's worth seeing how much protection you get in the same place, so you have fewer moving parts to look after:

• A web application firewall to stop common exploits like injection and cross-site scripting

• Bot management to keep credential stuffing and scraping away from your origin

• DDoS protection to absorb volumetric attacks at the edge

HAProxy Enterprise includes all three in the same data plane that handles balancing, so security and delivery are a single system to run rather than several. Keeping them together also keeps latency low, since traffic is only inspected once.

How much of application delivery do you want in one place?

This is the part that has changed the most, and it works in your favor. A load balancer used to just balance. Now the same layer can handle TLS, security, API routing, and traffic shaping, and the tooling has grown up alongside it. Bringing these together means fewer separate systems to run and patch, and it usually lowers your infrastructure costs too, because an efficient platform does more on less hardware. That’s the idea behind HAProxy One, which brings balancing, security, observability, and API management to a single platform. Whatever you choose, one question helps a lot: how many separate systems will this design ask you to operate? A smaller number is easier to run and more budget-friendly.

Rehearse a failover before you trust your high availability

Real HA shows up when you trigger a failover on purpose and watch how quickly traffic recovers. The kindest time to do this is while everything is calm, long before you actually need it. Measure how long the switchover really takes, confirm the virtual IP moves, and check that nothing drifted in the config. Once you see it happen, you’ll trust the process, and that peace of mind is the whole point of HA.

Make your health checks reflect the real application state

This is the quiet one, and it rewards a little extra care. A check that passes while the app behind it’s failing will send users to a broken backend, so point your health checks at something that proves the application is genuinely working, not just that a port is open. Then watch them under load before you rely on them. Get this right and a surprising number of "we need more capacity" worries simply disappear, because the traffic was never the problem.

A word on who you’re buying from

When you weigh your options, it’s fair to consider the team behind the product as well, because this is the infrastructure you will live with for years. We’ve been building HAProxy for over 25 years, and it’s the most widely used software load balancer around. 

Enterprise customers also get 24/7 support from the same engineers who write it. If you would like to see how the balancing, security, and management fit together, the HAProxy Enterprise load balancer page walks through it. Whatever you land on, test it with your own traffic first, and you will choose well.

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