Lakshay Mahajan

I’m a backend engineer who learns by building real systems, breaking them, and fixing them properly.


I began with full-stack apps to understand how everything connects — from the API someone calls to the session cookie that keeps them logged in. Over time, I found myself drawn to backend challenges: preventing payment manipulation, designing reliable auth flows, and making sure background jobs don’t fail silently.


One of my earliest fixes: rebuilding a society event platform where sessions broke on every refresh. I replaced localStorage sessions with secure JWT cookies and moved payment registration to backend webhooks — so once a payment succeeds, everything triggers automatically without frontend dependency.


As I worked on more projects, I started building reusable infrastructure instead of solving the same problems repeatedly. I built a centralized authentication service with Google OAuth, email/password authentication, asymmetric JWTs, rate limiting, and asynchronous email delivery. It now provides authentication across my projects.


More recently, I’ve been going deeper into transaction systems and concurrency. With Vaultex, I explored mutex locking, idempotency, duplicate requests, and TOCTOU race conditions — focusing not just on making systems work, but understanding where they can fail and the tradeoffs behind different solutions.


I also write technical deep-dives to document what I learn and the engineering decisions behind the systems I build. My writing covers topics such as payment architecture, OAuth 2.0, Access & Refresh Tokens, and SSL/TLS.


I also build personal tools around problems I’m actively solving. During my job search, I built Personal Hub to manage my work, projects, learning, and outreach, and I’m building Knowledge Graph to experiment with knowledge management. These are personal tools rather than portfolio projects, and I use them to explore ideas quickly and learn by building.


Alongside backend engineering, I’m currently learning Generative AI and exploring how it can be applied to the systems and tools I build.

If you’re working on authentication, payments, backend reliability, or systems that need to behave correctly under failure and concurrency — let’s connect.
📩 dev@lakshaymahajan.com