100%Drag from a component's right dot to another's left dot to connect. Click empty space + drag to pan. Delete/Backspace removes selection.
Build your first system
Drag components from the left onto the canvas and connect them.
How this simulator works
Drag components onto the canvas and connect them (drag from the small dot on the right edge of a component to the dot on the left edge of another) to build an architecture — for example Client → Load Balancer → App Server → Database.
Click a component to configure it in the Inspector tab: request rate, instance count, service rate, cache hit rate, rate limits, and more.
Press ▶ Run to start the simulation. Behind the scenes it recomputes real queueing-theory metrics every tick — M/M/c utilization, Erlang-C wait probability, and Little's-Law-derived latency percentiles — so what you see (utilization %, p50/p95/p99 latency, throughput, error rate) reflects the actual math used in capacity planning, not just a canned animation.
Use ⚡ Spike to temporarily multiply traffic and watch bottlenecks appear. Click the ⏻ power button on a component to crash it and see how traffic reroutes — or doesn't, if you haven't built in redundancy.
Drop a VPC, Subnet or Availability Zone from the Networking tab to group components visually, the way a real cloud deployment is organised — drag the container and everything inside moves with it.
Everything is saved only in your browser (autosave to local storage) — use Export / Import to save or load a design as a JSON file.