Every system design resource I found had the same problem: static diagrams and theoretical explanations. "Add a load balancer here." "Use caching." But what actually happens when your database hits 195 out of 200 connections? What does a cascading failure look like in real-time?
I couldn't find a tool that showed me, so I built one.
What is SysBreak?
SysBreak is a free, interactive platform where you learn system design by breaking things. Instead of reading about how systems fail, you watch them fail — and then fix them.
Here's how it works:
1. Pick a Real-World Scenario
Choose from situations like:
- Shark Tank Surge — Your startup gets featured on TV. Traffic jumps from 1K to 500K users in 5 minutes. What breaks first?
- Black Friday Sale — An e-commerce platform handling 10M concurrent users. Database connections maxing out, payment service timing out.
- Cascading Failure — One service goes down and takes everything with it. Can you isolate the blast radius?
2. Crank the Traffic Slider
Go from 100 users to 10 million. Watch the architecture respond in real-time:
- Error rates climb from 0.1% to 52%
- P99 latency spikes from 45ms to TIMEOUT
- Database connections fill up: 12/200 → 195/200
- Circuit breakers trip, cache hit rates fluctuate
3. Fix It by Dragging in Components
Add load balancers, Redis caching layers, database replicas, circuit breakers, CDN nodes — and watch the metrics recover live. You're not memorizing solutions, you're discovering them by seeing what works.
Sandbox Mode
Don't want a guided scenario? The sandbox mode lets you build any architecture from scratch. Drag in services, connect them, set traffic patterns, and see how your design holds up.
I use it to prototype architectures before whiteboard interviews.
Interview Lab
System design interviews are a different beast. The Interview Lab has real questions asked at top tech companies:
- "Design a URL shortener that handles 100M requests/day"
- "Design a real-time chat system like WhatsApp"
- "Design a notification service for 500M users"
Each question gives you a blank canvas, a timer, and the constraints. Build your answer visually, then see how your design handles the stated load.
The Tech Stack
- Frontend: React + TypeScript + Vite
- Backend/Auth: Supabase (PostgreSQL + Auth + RLS + Edge Functions)
- Hosting: Vercel
- Simulation Engine: Custom event-driven simulation that models queue theory, connection pools, cache behavior, and failure propagation
The simulation isn't just animation — it's based on actual system behavior patterns. When the database connection pool fills up, new requests queue and latency grows exponentially, just like it would in production.
Why I Built This
I'm a backend engineer working with Java, Spring Boot, Kafka, and Kubernetes. When I was preparing for system design interviews, I realized I could explain what to do but not why. I could say "add a cache" but I didn't have intuition for when caching helps vs. when it doesn't.
Building SysBreak forced me to model these systems mathematically — and now anyone can develop that same intuition by playing with it.
It's Free
Everything on SysBreak is free right now. No paywall, no premium scenarios. I'm focused on making it genuinely useful before thinking about monetization.
👉 Try it: sysbreak.dev
I'd love feedback from this community — what scenarios would you want to see? What would make this more useful for your learning or interview prep?
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