Field Notes
5 BlogsGuides and write-ups from things I've built, deployed and broken along the way.
AI & RAGHow to Build a Custom AI Chatbot with RAG Using Gemini, LangChain, Puppeteer.
A step-by-step guide to building a chatbot that answers questions from your own website content. You will scrape pages with Puppeteer, chunk them with LangChain, embed them with Gemini, store everything in MySQL with Prisma and retrieve answers using cosine similarity. You will also build the Next.js API route and a floating chat widget.
System Design & GeohashingHow Uber and Rapido Find Nearby Drivers
How ride apps find nearby drivers in milliseconds: Geohash narrows the search, Redis stores live locations and Haversine filters by radius. Worked example included.
AWSHow to Upload Images to Amazon S3 and Serve Them with CloudFront Signed URLs in Node.js
Store images in a private S3 bucket, optimize them with Sharp, and deliver them securely through CloudFront using short-lived signed URLs.
DevOpsAWS EC2 Production Deployment Guide
Ubuntu, a GitHub repo, Node.js, PM2, MySQL, Nginx, UFW, DNS and SSL. Take a Node.js app from an empty EC2 instance to a secured production URL.
System DesignBook My Show HLD Breakdown
Ticket booking looks simple: pick a seat, pay, done. The hard part is guaranteeing that one seat belongs to exactly one person.