karthik.dev

Technical Blog

Engineering Notes

Writing on AI engineering, system design, and building in public — the AI Recruiter Assistant can answer questions about these posts too.

Engineering

How I Built a Real-Time LeetCode Stats Dashboard with 2-Minute Polling

Behind the scenes of fetching live LeetCode data server-side, avoiding CORS, caching intelligently, and building a UI that tells you exactly when data is fresh.

7 min readRead
DSA

Why Every Developer Should Solve 50 Hard LeetCode Problems

Not because interviews ask for them — but because hard problems rewire how you think about constraints, edge cases, and trade-offs in production systems.

5 min readRead
Backend Engineering

Building a Payment Gateway from Scratch: What the Tutorials Don't Tell You

Idempotency keys, dead-letter queues, row-level locking, webhook retries — the unglamorous infrastructure that makes real money move correctly.

9 min readRead
Frontend Engineering

Scroll-Driven Animations with Canvas: How This Portfolio's Background Works

300 JPEG frames, a requestAnimationFrame loop, lerp-based smoothing, and a DPI-aware cover-fit algorithm — the full technical breakdown.

8 min readRead
Backend Engineering

Redis Caching Patterns That Actually Work in Production

Cache-aside, write-through, TTL strategies, and the cache invalidation problems that will bite you — from real experience building CodeMyFYP Academy.

7 min readRead
Frontend Engineering

Next.js App Router: Patterns I Use on Every Project

Server components, streaming, route groups, parallel routes, and the mental model shift that makes App Router click — from someone who's shipped multiple production apps with it.

8 min readRead
Engineering

From Founder to Engineer: What Building CodeMyFYP Taught Me About Systems

Starting a company at university and building the platform from scratch — the technical decisions, the mistakes, and the engineering instincts that came from owning every layer.

7 min readRead
DSA

Dynamic Programming: The Patterns Behind the Problems

After solving 60+ DP problems, I've found they mostly fall into five pattern families. Recognizing the family is 80% of solving the problem.

8 min readRead
Engineering

TypeScript Patterns I Use Every Day (And Why They Matter)

Discriminated unions, const assertions, template literal types, satisfies, and the pattern that finally made me stop fighting the type system.

6 min readRead
DSA

Graph Algorithms That Show Up Everywhere (And How to Spot Them)

BFS, DFS, Dijkstra, Union-Find, and topological sort — the five graph primitives that underlie hundreds of LeetCode problems and real system design challenges.

7 min readRead
AI Engineering

Prompt Engineering for Reliable AI Agents: What I Learned Building Career Agents

System prompts, JSON output schemas, temperature settings, chain-of-thought triggers, and the evaluation harness that tells you whether your prompts actually work.

7 min readRead
Backend Engineering

PostgreSQL Indexing: The Missing Guide for Application Developers

B-tree, partial, composite, and covering indexes — when to use each, how to verify they're being used, and the common mistakes that nullify your indexes entirely.

8 min readRead
DevOps

CI/CD with GitHub Actions: From Zero to Production-Ready Pipeline

How I set up automated lint, test, build, Docker, and deployment pipelines for my projects — the exact workflow files and the reasoning behind each step.

7 min readRead
AI Engineering

Designing Multi-Agent Systems That Don't Fall Apart in Production

Lessons from building Career Agents — why a single orchestrator, strict JSON contracts, and shared session memory matter more than clever prompts.

6 min readRead
Backend Engineering

JWT Authentication Done Right: Stateless Auth Without the Footguns

Access tokens, refresh tokens, secure storage, rotation strategies, and the common implementation mistakes that make JWT-based auth insecure — with fixes.

7 min readRead
Frontend Engineering

How I Optimized a Next.js App's Core Web Vitals from 60 to 95

LCP, CLS, FID — the actual changes (image optimization, font loading, code splitting, ISR) that moved the needle on real performance metrics.

6 min readRead
System Design

Five Roles, One Codebase: RBAC Lessons from a Multi-Tenant EdTech Platform

How CodeMyFYP Academy enforces data isolation across Students, Mentors, Recruiters, Faculty, and Administrators without duplicating business logic per role.

5 min readRead
SaaS Building

GTM Engineering: Why I Ship an llms.txt Next to My Sitemap

Technical SEO used to mean robots.txt and sitemaps. Now it also means making your site legible to AI crawlers and answer engines.

4 min readRead