HN Showcase
Back to browse
PaperDraw.dev – A System Design Simulator

PaperDraw.dev – A System Design Simulator

by vhatkarpratap·Mar 2, 2026·2 points·0 comments
Visit ProjectView on HN

AI Analysis

●●●BangerSolve My ProblemEye CandyRabbit Hole

System design meets flight simulator—watch traffic propagate, bottlenecks emerge, failures cascade.

Strengths
  • •Fills genuine gap: static diagramming tools don't simulate behavior; answering 'what breaks first?' is novel for interviews
  • •Interactive component drag-drop + real-time physics simulation reduces abstraction gap vs static diagrams
  • •Well-scoped problem with clear value prop for system design interview prep market
Weaknesses
  • •Early-stage product; unclear if simulation physics accurately reflects real distributed systems
  • •No visible integration with interview prep platforms or metrics showing interview performance gains from tool
Category
Education
Target Audience

Software engineers preparing for system design interviews, infrastructure designers

Post Description

Hi HN

I recently built PaperDraw.dev, a browser-based system design simulator aimed at helping engineers practice real system design thinking, not just draw static diagrams.

Most tools today are diagramming tools. They help you draw boxes and arrows, but they don’t help you answer questions like:

• What happens when traffic spikes 10×? • Where does the bottleneck appear? • How does latency propagate across services? • What breaks first under load?

That’s the gap I wanted to solve.

What it does

PaperDraw is not just a whiteboard — it’s a simulation engine for system design.

You can:

Drag and drop components like LB, Cache, DB, Queues, Services

Connect them visually

Configure throughput, latency, capacity limits

Run real-time traffic simulations

Watch bottlenecks and failures emerge

It’s essentially trying to make system design more like a flight simulator, instead of a static drawing exercise.

Why I built this

I’ve conducted and taken many system design interviews over the years, and noticed:

People memorize patterns instead of understanding trade-offs

There’s no way to experiment with architectures

Students struggle to visualize scale dynamics

So I built this as a learning + experimentation tool.

Current usage

Launched ~10 days ago:

~1k–1.5k daily users

Mostly from developers preparing for interviews

What I’d love feedback on

Does the simulation concept feel useful?

What components or scenarios should be added?

Would templates for common architectures help?

Try it here: https://paperdraw.dev

Would really appreciate your thoughts

Similar Projects