Most saved content gets lost because keyword search can't match how you actually remember things. Brainly is an AI-powered knowledge management platform for saving and retrieving content from YouTube, X, articles, and other sources using semantic search instead of keyword matching. Metadata extraction and AI embedding generation run asynchronously through an event-driven architecture built on Cloudflare Queues and a dedicated processor worker, keeping API response latency low. Semantic search itself is powered by Workers AI, pgvector, and PostgreSQL, enabling natural-language content retrieval through vector similarity search. Serverless APIs are built with Hono on Cloudflare Workers and secured with stateless JWT authentication for low-latency edge execution. The whole application is architected as a Turborepo monorepo with shared packages for database access, AI services, and common utilities, improving maintainability and code reuse.

Real-time collaboration is an engineering problem, not just a feature — when multiple users draw simultaneously, strokes must arrive in the right order and render without flicker. Draw App uses a persistent WebSocket server to broadcast canvas events to all connected clients instantly, with room-based session isolation so concurrent whiteboards never bleed into each other. The Turborepo monorepo splits the WebSocket server, Next.js frontend, and shared type definitions into separate packages — so a protocol change surfaces as a TypeScript error before it ever hits production.

Building a payment platform means getting security, consistency, and UX right at the same time. PayWallet handles peer-to-peer transfers with OTP-verified login via Twilio, atomic database transactions to prevent double-spend, and bank webhook processing for fund settlements. The merchant portal runs alongside the consumer app in a Turborepo monorepo — both Next.js apps share a common Prisma schema, NextAuth config, and ShadCN UI component library, so auth and data-model changes propagate safely across both surfaces without duplication.

Resizely turns heavy media processing into a self-service product with built-in monetization. Users purchase credits via Razorpay, then spend them on image resizing, video compression, and AI background removal — each operation deducts the appropriate credit cost atomically to prevent race conditions under concurrent requests. Cloudinary handles media transformation and CDN delivery, offloading the compute-heavy work. Admins get a dedicated dashboard with per-user credit balances, consumption history, and revenue breakdowns — all without a separate service.

A production-grade REST API covering the full surface of a video platform: upload, stream, comment, like, subscribe, and tweet. MongoDB aggregation pipelines power the subscription feed, watch history, and channel analytics — no N+1 queries. Auth uses short-lived JWT access tokens paired with rotating refresh tokens stored in HTTP-only cookies, keeping sessions stateless on the server. Indexes are tuned per query pattern so hot paths stay fast as data volume grows.