Prove your skills

# Build a Retro OS Simulator Build a nostalgic desktop environment with windowed applications, a file manager, and a terminal. ## Requirements - Desktop with wallpaper, taskbar at bottom, clock in system tray - Window management: open, close, minimize, maximize, drag to move, resize - File manager app: navigate folders, create/rename/delete files (virtual filesystem) - Notepad app: simple text editor with save/open from virtual filesystem - Terminal app: basic commands (ls, cd, cat, mkdir, echo, clear, help) - Start menu with application list - Multiple windows can be open simultaneously with proper z-ordering - Window focus management (click to bring to front) ## Technical Notes All in-browser, no backend needed. Virtual filesystem stored in state. Window management is the core challenge. ## Bonus Points - Calculator app - Paint app (simple drawing canvas) - Boot sequence animation on load - System sounds (click, open, close, error)

# Build a Pub/Sub Message Broker Build a publish/subscribe message broker with topics, subscriptions, and delivery guarantees. ## Requirements - Topics: create, list, delete - Subscriptions: subscribe to topics, unsubscribe - Publish messages to topics, deliver to all subscribers - At-least-once delivery: messages persist until acknowledged - Message acknowledgment: subscriber confirms receipt - Dead letter topic: unacknowledged messages after 3 retries - Dashboard: topic list, message rates, subscriber counts, pending messages - HTTP API for all operations ## Technical Notes Store messages in a database. Messages have a visibility timeout. Delivery via push to endpoints or pull via API. ## Bonus Points - Message filtering (attribute-based routing) - Fan-out patterns (one message to many subscribers) - Message ordering guarantees per topic

# Build a Job Queue with Dashboard Build a job queue system with worker processes, retry logic, and real-time monitoring. ## Requirements - Enqueue jobs with: type, payload, priority (low/normal/high/critical) - Worker that picks up and processes jobs (simulated with configurable delay) - Retry logic: failed jobs retry up to 3 times with exponential backoff - Job states: PENDING, RUNNING, COMPLETED, FAILED, RETRY, DEAD - Real-time dashboard: queue depth, processing rate, success/failure counts - Job detail view: state history, attempt logs, timing - Batch operations: pause queue, resume, purge dead jobs ## Technical Notes Use a database table as the queue. Workers poll for jobs. Dashboard updates via polling or WebSocket. ## Bonus Points - Concurrent worker pool (configurable parallelism) - Job scheduling (run at specific time) - Dead letter queue with manual retry

# Build a Micro-Marketplace Build a mini marketplace where users can list items for sale, add to cart, and complete checkout. ## Requirements - User auth (signup/login) - Seller: create listings with title, description, price, images - Buyer: browse listings in a grid, search by name, filter by category and price range - Product detail page with image gallery - Shopping cart with quantity adjustment - Checkout flow: shipping info form, order summary, confirm (no real payment) - Seller dashboard showing their listings and orders - Order status tracking (pending, shipped, delivered) ## Technical Notes Use Next.js with database (Prisma + SQLite for simplicity). Auth via NextAuth or session-based. ## Bonus Points - Review/rating system - Saved items / wishlist - Stripe test mode integration

# Build a Real-Time Collaborative Editor Build a Google Docs-style collaborative text editor where multiple users edit simultaneously. ## Requirements - Rich text editor with bold, italic, headings, lists, and code blocks - Real-time collaboration: multiple cursors visible, changes sync instantly - Conflict resolution: concurrent edits don't corrupt the document - User presence indicators (colored cursors with names) - Document list with create/rename/delete - Share document via unique link - Offline support: edits queue and sync when reconnected ## Technical Notes Use CRDTs (Yjs or Automerge) or OT (ShareDB) for conflict resolution. WebSocket for real-time sync. Rich text editor: Tiptap, Slate, or Lexical. ## Bonus Points - Version history with ability to restore - Comments and suggestions mode - Export as Markdown/HTML/PDF

# Build an AI Code Review Tool Build a tool that uses AI to review pull requests and provide actionable code feedback. ## Requirements - GitHub-style diff viewer - AI-powered review comments on specific lines - Severity levels: info, suggestion, warning, critical - Summary view of all findings - Accept/dismiss individual comments - Export review as markdown