# Paperdraw — System Design Simulator

> Paperdraw is an interactive system design tool that lets engineers draw distributed architectures and simulate them under real traffic with chaos engineering. Available at https://paperdraw.dev

## What is Paperdraw?

Paperdraw is a browser-based system design simulator. You drag and drop components (load balancers, databases, caches, queues, microservices) onto a canvas, connect them, then run a live simulation that models real traffic, queueing theory (M/M/c), cascading failures, and chaos events.

Unlike static diagram tools (Lucidchart, draw.io, Miro), Paperdraw simulates:
- Requests per second flowing through each component
- CPU utilization, queue depth, error rates per node
- Cascading failure propagation
- 72 chaos events (network partition, disk failure, memory leak, cache stampede, etc.)
- Auto-scaling (HPA-style), circuit breakers, retry storms

## Use Cases

- System design interview preparation
- Architecture review before production deployment
- Teaching distributed systems concepts
- Stress-testing designs before writing code
- Demonstrating failure modes to stakeholders

## Problems Paperdraw Helps Solve

See the following pages for detailed problem walkthroughs:
- /design-url-shortener.md — Design a URL shortener (TinyURL/Bitly)
- /design-rate-limiter.md — Design a rate limiter
- /design-notification-system.md — Design a notification system
- /design-chat-system.md — Design a real-time chat system (WhatsApp/Slack)
- /design-video-streaming.md — Design a video streaming platform (YouTube/Netflix)
- /design-ride-sharing.md — Design a ride-sharing system (Uber/Lyft)
- /design-search-autocomplete.md — Design a search autocomplete system
- /design-distributed-cache.md — Design a distributed cache
- /design-api-gateway.md — Design an API gateway
- /design-newsfeed.md — Design a social media newsfeed (Twitter/Instagram)

## Pricing

- Free: 1 simulation run per day
- Paperdraw+: $5/month — unlimited simulations, 72 chaos events, cloud sync

## Links

- Homepage: https://paperdraw.dev
- Pricing: https://paperdraw.dev/plus
- App: https://paperdraw.dev