System Design Simulator
Build distributed architectures on a live canvas, simulate 1K–100K users, visualize bottlenecks, configure nodes, and learn with explain mode.
System Design Simulator
Build infrastructure, simulate traffic, and learn scaling interactively.
System Design Simulator guide
Developer Tool
Understanding distributed systems is easier when you can see traffic move through real components—not just boxes on a slide. The System Design Simulator lets you compose infrastructure from clients, CDNs, load balancers, API servers, caches, databases, queues, and workers, then stress the graph with simulated user loads. A lightweight engine propagates requests, computes utilization, latency, drops, and cache effectiveness while the canvas animates health states and packet flow along edges. Whether you are preparing for interviews, teaching a class, or reviewing an architecture doc, you can toggle Explain Architecture to get contextual guidance on each node's role and why bottlenecks emerge.
What is a system design simulator?
Unlike a static diagram editor, a system design simulator models how load travels through connected components. You place nodes, wire dependencies, configure capacities (API throughput, Redis hit rate, database concurrency), and run simulations at 1K, 10K, or 100K users. Overloaded nodes pulse red; healthy paths glow green; metrics update live in a dashboard powered by throughput and latency charts.
This approach bridges visual architecture and quantitative reasoning—the same skills senior engineers use when sizing clusters, choosing cache strategies, or deciding when to introduce async workers.
How to use this tool
Start from a template (Simple MERN, High Traffic API, Chat, or E-commerce) or drag nodes from the palette onto the canvas. Connect handles left-to-right to define request paths. Click a node to open the configuration drawer—tune API autoscaling, Redis hit rate, or Postgres query limits. Press Simulate to watch traffic propagate; open Explain Architecture to hover nodes for educational tooltips about bottlenecks, cache misses, and scaling pressure.
Use Ctrl+K for the command palette (templates, simulations, explain toggle). Press Escape to stop a run or close panels. Delete removes the selected node when focus is not in an input field.
Learning outcomes
You will see why caches reduce database pressure, how load balancers hide horizontal scale, and when queues protect APIs from spikes. Running 100K users on an undersized API tier makes drops and latency tangible—far more memorable than reading a textbook curve.
Pair this tool with the Data Flow Visualizer for pipeline documentation and the Schema Visualizer for data model context when designing full stacks.
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