# Biswajeet Das

> Lead Software Engineer with 6+ years building backend services, SDKs, and full-stack products. Currently Lead Product Engineer at Lightwork AI, where he architected a zero-trust security model across the microservices and built the realtime WebSocket layer. Previously at Novu, architected parts of the core workflow orchestration engine, created @novu/react and @novu/next from scratch, and architected @novu/client. Creator of hour.zone, Hexbench, EngineView, miny, Bracket Wars, @biswaviraj/time-travel, and @biswaviraj/cc-setup.

Based in India. Happiest in the parts most people skip: data layers, auth flows, cache invalidation, rate limiting, the wiring that decides whether a system actually works. An all-rounder by choice, he ships across React, Vue, SvelteKit, and SolidJS, with some Python and Go. 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): Lead engineer on an AI-powered property-management platform, working mostly across the backend recently.
  - **Zero-trust security (architected, leading):** designed and leads a zero-trust security model across all microservices. Each request carries a signed JWT, verified via JWKS, that downstream services authorize independently. A cross-team initiative spanning the data, AI, and DevOps teams, owned end to end from ADR and technical spec to design presentations.
  - **Realtime:** built the WebSocket layer end to end, backend and frontend: the NestJS gateway and the client that consumes it.
  - **Backend:** NestJS microservices with TCP transport between services, Google Pub/Sub eventing, Postgres and MongoDB, and Better Auth.
  - **Voice AI:** integrated voice AI agents that handle live calls, building the API and call-handling layer around the LLM.
  - **Frontend and delivery:** co-led the migration from a legacy React Router app to a modern Next.js stack (Tailwind + shadcn); set up feature flags and PostHog analytics; scopes features with the CEO and Product and ships from API to UI.

- **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): Owned most of the frontend for Blink Payment, a fintech payment-gateway platform. Built payment flows (virtual terminals, repeat payments) and integrated card processors Cardstream and SagePay. Deployed via AWS CodePipeline, CodeBuild, and CloudFront.

- **NetTantra Technologies · Software Developer** (January 2020 - January 2021): Sole frontend engineer on ZipDJ, a Spotify-style streaming platform built for DJs. Owned the frontend end to end, including the custom music player at the heart of the product. Integrated ElasticSearch for search and used eager loading for performance. Also integrated Mega.nz cloud storage for Spinvault.

## Projects

- [EngineView](https://github.com/BiswaViraj/engineview): Multi-user, self-hosted dashboards and a SQL query runner for Cloudflare Analytics Engine: turn raw Analytics Engine data into shareable charts and ad-hoc queries without living in the Cloudflare dashboard.
- [agent-skills](https://github.com/BiswaViraj/agent-skills): A portable agent-skills marketplace: reviewloop (clear every PR reviewer), ciloop (drive failing CI to green), and standup (daily standup from your PRs), installable per-skill across Claude Code, GitHub Copilot CLI, Codex, and Cursor from one SKILL.md source.
- [miny](https://miny.in): Share anything: links, files, or code snippets, briefly or forever. Auto-expiring by default, permanent when you want it.
- [@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.
- [Hexbench](https://hexbench.app): A fast, private developer toolbox that runs entirely in your browser: format, decode, diff, hash, and test, with nothing you paste ever leaving the page. No install, works offline.
- [hour.zone](https://hour.zone): Timezone comparison for remote teams. Static Astro + React islands with 720+ pre-rendered pair pages and abbreviation hubs (/ist, /pst, /gmt...). All timezone math client-side via native Intl. Zero backend, zero signup, URL-shareable (hour.zone/bangalore/san-francisco).
- [Bracket Wars](https://bracketwars.app): A mobile-first sports bracket prediction game: call the upsets, climb the rankings, and settle who actually knows the game.
- [@novu/react](https://www.npmjs.com/package/@novu/react): React SDK for Novu, built from scratch as a modern, lightweight replacement for `@novu/notification-center` with faster load, an 85%-smaller bundle, and composable headless primitives. Overtook the legacy package in npm weekly downloads within months.
- [@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.

## Skills

TypeScript, JavaScript, Node.js, NestJS, Microservices, WebSockets, TCP transport, Google Pub/Sub, Event-Driven Architecture, REST APIs, PostgreSQL, MongoDB, Redis, BullMQ, Better Auth, Authentication and Security, Zero-Trust Security, Kubernetes, AWS, React, Next.js, Vue, SvelteKit, SolidJS, Tailwind CSS, shadcn/ui, UI/UX, Voice AI integration, Python, Go, Open Source, SDK Development, Developer Tools, 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