System design simulator — traffic, chaos & AWS costs in your browser. Practice distributed architecture and system design interviews with a free Rust→WASM discrete-event engine, 57 blueprints, 28 chaos scenarios. No signup.

Design. Simulate. Scale.

Simulate traffic and chaos on your diagram —
not just static boxes and arrows.

18 component types · networking, compute, data 28 chaos scenarios · inject failures, observe recovery 57 blueprints · E-Commerce, Chat, IoT, MCP Agents Real-time AWS cost estimation as you build Rust-powered WASM simulation engine
Start Simulation → Learn More

System design simulator in your browser — traffic, chaos, and AWS cost signals on the canvas.

Rust → WASM discrete-event engine · 57 blueprints · 28 chaos scenarios · no signup

Why not just a whiteboard? Compare to diagram tools →

system-design-emulator-ten.vercel.app/emulator
EXTERNAL NETWORKING COMPUTE DATA & MESSAGING CLIENT 10K RPS LOAD BALANCER ROUND ROBIN API GATEWAY RATE LIMIT APP SERVER CLUSTER x3 CACHE REDIS · 98% HIT DATABASE POSTGRES · PRIMARY MSG QUEUE KAFKA · 3 TOPICS LATENCY P50 12ms P95 48ms P99 120ms THROUGHPUT 9,847 RPS
Chaos engineering — latency, partitions, crashes & more
AWS cost estimates from your architecture topology
Live metrics — status bar, on-canvas readouts, full analysis page
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Component Types
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Chaos Scenarios
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Blueprints
Architectures

What's Inside

Everything you need to
think in systems

Visual Diagram Editor

Map services on an infinite canvas for system design interviews and team reviews: drag-and-drop components, bezier wires, multi-select, undo/redo, zoom, and auto layout with optional layout zones for custom columns.

Rust-Powered Simulation

Discrete-event simulation (DES) in WebAssembly drives request flow through your diagram at configurable RPS — a living architecture simulator, not a static sketch.

28 Chaos Scenarios

Practice resilience testing: node crashes, partitions, memory pressure, and MCP-only chaos scenarios on AI agent blueprints.

AWS Cost Estimation

Rough-order AWS pricing mapped to your boxes — EC2, Lambda, RDS, ElastiCache, and more — so cost tradeoffs stay visible while you iterate.

Live metrics & analysis

While the sim runs: a top status bar (RPS, p99, errors, bottlenecks), readouts on nodes, and toolbar Metrics opens a full-page System metrics analysis view with latency history and bottleneck callouts—built for interview and SRE-style narratives.

57 Production Blueprints

Start from real patterns — e-commerce, chat, serverless APIs, IoT, exchanges, ML pipelines, MCP agents — then stress-test with simulation and chaos.

Share & Export

Copy share link creates a short URL—your diagram is stored server-side with a 7-day expiry so big designs share cleanly. For something permanent, use export JSON or PNG.

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Your infrastructure
awaits.

No login. No credit card. No nonsense.
Just you, a canvas, and infinite possibilities.

Or don't. We'll be here. Waiting. Patiently.

Built By

The humans (& not-so-humans)
behind this.

Two contributors. One context window.
No standups. No Jira. No regrets.

ronit@sysdesign
whoami
Ronit
uname -r
Full-Stack Engineer
cat ./stack.sh
Rust · WASM · Flutter · Dart
./tldr --this-project
Browser-native sim engine.
Rust → WASM → Flutter.
WASM-first sim. Light serverless for shares & feedback.
claude@anthropic
whoami
Claude
uname -r
AI Coding Assistant
cat ./stack.sh
LLM · Code Gen · Context
./tldr --this-project
Helped ship it faster.
Some of the code is mine.
None of the vision is.