# DesignDojo

> Free, unlimited system design and low-level design interview practice. Walk through real interview problems stage-by-stage with AI feedback. Bring your own AI key — or run a local model. No subscriptions, ever.

## About

DesignDojo is an open-source interview-prep tool for software engineers preparing for system design (HLD) and low-level design (LLD) interviews at FAANG and similar companies. Each problem comes with: (1) a written walkthrough article that breaks down the problem like a senior interviewer would, and (2) an interactive practice mode where an AI tutor coaches you stage-by-stage (requirements → estimation → API design → data model → high-level diagram → deep dives) and grades your answers against a senior-engineer rubric.

Author: Aditya Jindal (https://adysfolio.vercel.app)
Site: https://getdesigndojo.vercel.app

## Key URLs

- [Home](https://getdesigndojo.vercel.app/): Overview and entry points.
- [About](https://getdesigndojo.vercel.app/about): What DesignDojo is and why.
- [FAQ](https://getdesigndojo.vercel.app/faq): BYOK, providers, costs, privacy.
- [Practice — System Design](https://getdesigndojo.vercel.app/practice/system-design): Browse and start HLD problems.
- [Practice — Low-Level Design](https://getdesigndojo.vercel.app/practice/low-level-design): Browse and start LLD problems.
- [Write-ups index](https://getdesigndojo.vercel.app/learn): All HLD + LLD interview walkthroughs.
- [vs HelloInterview](https://getdesigndojo.vercel.app/vs/hellointerview): Comparison + non-affiliation disclaimer.
- [Privacy](https://getdesigndojo.vercel.app/privacy): Data handling.
- [Contact](https://getdesigndojo.vercel.app/contact): Bug reports + feedback.

## System Design (HLD) write-ups

- [Ad Click Aggregator](https://getdesigndojo.vercel.app/learn/system-design/ad-click-aggregator)
- [Bitly](https://getdesigndojo.vercel.app/learn/system-design/bitly)
- [Distributed Cache](https://getdesigndojo.vercel.app/learn/system-design/distributed-cache)
- [Dropbox](https://getdesigndojo.vercel.app/learn/system-design/dropbox)
- [FB Live Comments](https://getdesigndojo.vercel.app/learn/system-design/fb-live-comments)
- [FB News Feed](https://getdesigndojo.vercel.app/learn/system-design/fb-news-feed)
- [FB Post Search](https://getdesigndojo.vercel.app/learn/system-design/fb-post-search)
- [Google Docs](https://getdesigndojo.vercel.app/learn/system-design/google-docs)
- [Instagram](https://getdesigndojo.vercel.app/learn/system-design/instagram)
- [Job Scheduler](https://getdesigndojo.vercel.app/learn/system-design/job-scheduler)
- [LeetCode](https://getdesigndojo.vercel.app/learn/system-design/leetcode)
- [Local Delivery Service](https://getdesigndojo.vercel.app/learn/system-design/local-delivery)
- [Metrics Monitoring](https://getdesigndojo.vercel.app/learn/system-design/metrics-monitoring)
- [News Aggregator](https://getdesigndojo.vercel.app/learn/system-design/news-aggregator)
- [Online Auction](https://getdesigndojo.vercel.app/learn/system-design/online-auction)
- [Payment System](https://getdesigndojo.vercel.app/learn/system-design/payment-system)
- [Price Tracking Service](https://getdesigndojo.vercel.app/learn/system-design/price-tracker)
- [Rate Limiter](https://getdesigndojo.vercel.app/learn/system-design/rate-limiter)
- [Robinhood](https://getdesigndojo.vercel.app/learn/system-design/robinhood)
- [Strava](https://getdesigndojo.vercel.app/learn/system-design/strava)
- [Ticketmaster](https://getdesigndojo.vercel.app/learn/system-design/ticketmaster)
- [Tinder](https://getdesigndojo.vercel.app/learn/system-design/tinder)
- [Uber](https://getdesigndojo.vercel.app/learn/system-design/uber)
- [Web Crawler](https://getdesigndojo.vercel.app/learn/system-design/web-crawler)
- [WhatsApp](https://getdesigndojo.vercel.app/learn/system-design/whatsapp)
- [Yelp](https://getdesigndojo.vercel.app/learn/system-design/yelp)
- [YouTube Top K](https://getdesigndojo.vercel.app/learn/system-design/youtube-top-k)
- [YouTube](https://getdesigndojo.vercel.app/learn/system-design/youtube)

## Low-Level Design (LLD) write-ups

- [Amazon Locker](https://getdesigndojo.vercel.app/learn/low-level-design/amazon-locker)
- [Connect Four](https://getdesigndojo.vercel.app/learn/low-level-design/connect-four)
- [Elevator](https://getdesigndojo.vercel.app/learn/low-level-design/elevator)
- [File System](https://getdesigndojo.vercel.app/learn/low-level-design/file-system)
- [Inventory Management](https://getdesigndojo.vercel.app/learn/low-level-design/inventory-management)
- [Movie Ticket Booking](https://getdesigndojo.vercel.app/learn/low-level-design/movie-booking)
- [Parking Lot](https://getdesigndojo.vercel.app/learn/low-level-design/parking-lot)
- [Rate Limiter](https://getdesigndojo.vercel.app/learn/low-level-design/rate-limiter-lld)

## Optional

- All content is free and human-written. Articles credit Aditya Jindal.
- The app stores AI keys only in your browser — never on a server.