Load Balancer Simulator

Visualize Round Robin, Least Connections, IP Hash and Weighted algorithms distributing requests.

Rate:2/s

Gold dots = requests in flight. Click server buttons to toggle them on/off. Adjust rate to simulate load.

What the load balancer simulator shows

Watch incoming requests get distributed across a pool of servers using Round Robin, Least Connections, IP Hash, and Weighted algorithms. As traffic flows you can see which servers stay busy, which sit idle, and how each strategy reacts when a server is slow or gets more capacity.

How load balancing works

A load balancer sits in front of your servers and decides where each request goes. Round Robin cycles through servers evenly — simple and fair when requests are similar. Least Connections sends the next request to the least-busy server — better when request durations vary. IP Hash routes a given client to the same server every time (useful for session stickiness). Weighted variants send more traffic to bigger machines.

Why it matters

Load balancing is how a service scales past one machine and stays up when one fails. Choosing the wrong algorithm causes hot spots — one server melting while others idle. For the infrastructure that sits behind the balancer, see Kubernetes vs Docker Compose.

Frequently asked questions

Round Robin vs Least Connections — which should I use?

Round Robin when requests take roughly equal time; Least Connections when some requests are much longer than others, so load reflects actual work, not just count.

What is a sticky session?

Routing a client consistently to the same server (often via IP Hash or a cookie) so in-memory session state stays valid. It trades some balancing evenness for simplicity.

What's the difference between L4 and L7 load balancing?

Layer 4 balances on IP/port without inspecting content; Layer 7 understands HTTP and can route by URL, header, or cookie — more flexible, slightly more overhead.