# Biswajeet Das

> Product Engineer with 6+ years building backend services, SDKs, and full-stack products. Architected parts of Novu's core workflow orchestration engine, created @novu/react and @novu/next from scratch, and architected @novu/client. Currently Lead Product Engineer at Lightwork AI. Creator of @biswaviraj/time-travel.

Based in India. Comfortable in the parts most people skip: data layers, auth flows, cache invalidation, rate limiting, the wiring that decides whether a system actually works. Open to collaboration on hard problems.

- Website: https://biswajeetdas.com
- Email: biswajeetdas18@gmail.com
- Résumé: https://biswajeetdas.com/resume.pdf

## Experience

- **Lightwork AI · Product Engineer (Lead)** (June 2025 – Present): Leading full-stack development on an AI-powered property management platform. Architected realtime chat and event-driven workflows on NestJS microservices + WebSockets backed by MongoDB and Redis. Migrated legacy UI to Next.js + Tailwind + shadcn. Established feature flags, PostHog analytics, and scalable processes across teams.

- **Novu · Software Engineer** (Sept 2022 – June 2025): Architected and built parts of Novu's core notification orchestration engine. The workflow system walks a trigger through a configurable multi-step pipeline across email, inbox, SMS, and chat, with subscriber-preference evaluation at every layer.
  - **Workflow engine and APIs (NestJS / MongoDB / Redis / BullMQ):**
    - Shipped the new `/workflows` API (CQRS-style use-cases + commands) replacing the legacy `notification-templates` system that governs the orchestration pipeline.
    - Built the step-condition system end-to-end, using `react-querybuilder` on both UI and backend to let users author arbitrary per-step conditions and serialize them into JSON schemas the engine evaluates at runtime.
    - Designed the global subscriber preferences engine end-to-end (DAL schema migration, use-cases, `send-message` worker filter honored at every step of the pipeline, widgets controller, headless and node SDKs).
    - Hardened auth: password-reset rate limiting (5/min, 15/day), account lockout after 5 failed logins, shared password policy, username-enumeration timing fix.
    - DAL: cursor pagination with `includeCursor` and reverse-sort for backwards pagination; cache invalidation on template promotion.
    - Worker / providers: Twilio-backed Novu SMS provider with Gupshup DLT compliance (India TRAI) and customData overrides.
  - **SDKs:**
    - Created `@novu/react` and `@novu/next` from scratch. `@novu/react` surpassed the legacy `@novu/notification-center` package in [npm weekly downloads](https://npmtrends.com/@novu/js-vs-@novu/notification-center-vs-@novu/react) within months of launch, validating the rewrite's performance and DX gains.
    - Led architecture and build pipeline on `@novu/js` (with a teammate shipping alongside). The architecture cut bundle size 85% (157KB → 21KB) and load time 86% vs the legacy `@novu/notification-center`.
    - 100% architected `@novu/client` and rewrote it off axios onto native fetch.
    - Refactored `@novu/js` from singleton to DI so multiple inbox instances stop sharing auth state.

- **Capital Numbers · Software Developer** (March 2021 – August 2022): Led frontend for Blink Payment, a Payment Gateway as a Service. Built Blink Pages, integrated Cardstream and SagePay, shipped virtual terminals and repeat payments. Deployed via AWS CodePipeline, CodeBuild, and CloudFront.

- **NetTantra Technologies · Software Developer** (January 2020 – January 2021): Built responsive UIs for ZipDJ music streaming. Custom music player, eager-loading perf improvements, ElasticSearch-backed search. Integrated Mega.nz cloud storage for Spinvault.

## Projects

- [@biswaviraj/time-travel](https://www.npmjs.com/package/@biswaviraj/time-travel): Zero-dependency TypeScript state-history engine. Bounded past/present/future buffers, multi-step traversal via `go(n)`, opt-in pub/sub with lazy Set allocation. Fully typed, unit-tested, published to npm with a semantic-release pipeline and Astro/Starlight docs.
- [@biswaviraj/cc-setup](https://github.com/BiswaViraj/cc-setup): TypeScript CLI that orchestrates Claude Code plugin + MCP installs from a merged built-in/user registry. One command replaces a pile of ceremony.
- [PlaYT](https://github.com/BiswaViraj/playt): Terminal CLI to stream or download YouTube audio. Node.js + VLC integration with local caching.

## Skills

TypeScript, Node.js, NestJS, MongoDB, Redis, BullMQ, WebSockets, Microservices, Event-Driven Architecture, REST APIs, Authentication and Security, React, Next.js, SolidJS, JavaScript, Tailwind CSS, shadcn/ui, AWS, Open Source, SDK Development, Full-stack Development, Backend Engineering, Distributed Systems, Web Performance.

## Links

- GitHub: https://github.com/biswaviraj
- LinkedIn: https://www.linkedin.com/in/biswajeet-das/
- Twitter/X: https://twitter.com/biswaviraj