System design interview prep
Stop memorizing.
Start building.
Chinilla is a visual tool where you design a system, simulate real traffic through it, and see exactly where it breaks. Like a flight simulator for system design.
No sign-up needed. Free tier, no credit card.
You've read the book. You've watched the videos.
Can you prove your design actually works?
System design interviews ask you to build something and explain why it won't fall apart under pressure. Reading about load balancers isn't the same as watching your database choke when traffic spikes. Chinilla lets you see it happen, fix it, and build the intuition that interviewers are actually testing for.
How it works
Design your system
Drag components onto a canvas and wire them together. Pick a classic interview problem like a URL shortener or chat app, or start from scratch.
Hit play and watch it run
Simulated traffic flows through your system in real time. You'll see queues fill up, databases get overwhelmed, and bottlenecks form. Scrub the timeline to inspect any moment.
Fix what breaks, run it again
Tune capacity, add replicas, rethink your design. Simulate again. Repeat until it holds. That loop is how you build real intuition, not memorization.
See your system work (or break) in real time
Packets flow through connections. Queues fill up. Components flash red when they're dropping requests. Hover anything for live stats, or scrub the timeline to replay any moment.
Drop code. Get architecture.
Paste a Python file and Chinilla AI turns it into a visual architecture diagram you can simulate. Great for reverse-engineering real codebases.
What you can do with Chinilla
Books teach patterns. Chinilla lets you test them.
Whiteboards are static. This isn't.
Draw a system on Excalidraw and you have a picture. Build it in Chinilla and you can run traffic through it, break it, fix it, and prove it works.
Flashcards teach vocabulary. This builds intuition.
Knowing what a load balancer does is different from watching one save your system from a traffic spike. Simulation gives you the "aha" moments that stick.
Mock interviews cost $200/hr. This is free.
Practice as much as you want: design, simulate, iterate. The free tier includes everything you need. No time limits, no paywalls on core features.
Works for any domain, not just software
The same 7 blocks model a backend, a restaurant kitchen, a hospital, or a supply chain. System design is about first principles, and Chinilla makes that obvious.
A structured path from zero to interview-ready
8 classic interview problems, ready to simulate
URL shortener, chat app, rate limiter, notification system, CDN, news feed, file uploads, and pub/sub messaging. Each one is fully wired with realistic behaviors and costs. Load it, run it, break it.
Guided lessons inside the IDE
Step-by-step courses walk you through building real systems. Each lesson teaches a concept (queues, bottlenecks, retry logic) by having you build and test it yourself.
AI that explains why your design fails
Ask Chinilla AI what's wrong, get suggestions to fix it, and learn the patterns interviewers look for. It works with you, not as a black box.
Earn certificates when you finish
Complete a module, earn a badge. Finish all modules, get a certificate you can export and share. Proof that you didn't just read about systems, you built them.
Your next interview is coming.
Practice by building, not reading.
Free to start. No account needed for the demo.
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