MPortfolio

Mustkeem K

Senior Full Stack Engineer | React · Next.js · Nest.js · Node.js · TypeScript

Noida, India · Remote (NZ/APAC, EU and US-morning overlap)

Senior Full Stack Engineer with 9+ years building and operating high-traffic TypeScript products end to end. Currently working on VeVe's 3.2M-MAU marketplace for digital collectibles and comics, from checkout through wallet and bank payouts, with React, Next.js, Nest.js, Node.js, GraphQL, Kafka, RabbitMQ and AWS. Known for RFC-driven architecture, payment-grade reliability (99.95% SLO, idempotent money flows), Next.js performance (p75 LCP from 3.8 s to 1.9 s) and raising team delivery from weekly releases to ~25 deploys a day. Mentor and interviewer, early adopter of AI-native development with Claude Code, and remote-first since 2020.

mo.mustkem@gmail.com+91-8130128030LinkedInGitHubStack Overflow · 8K+ rep

Technical Skills

Languages
TypeScriptJavaScript (ES2023)SQLHTMLCSS
Frontend
ReactNext.js (App Router, RSC, SSR/SSG/ISR)React NativeReduxRedux ToolkitReact Query/TanStack QueryZustandApollo ClientWebSocketsTailwind CSSMaterial-UIshadcn/uiSASSLESSStorybookDesign systemsCore Web VitalsAccessibility (WCAG 2.2 AA)
Build Tools & Optimization
WebpackViteBabelCode splittingLazy loadingCachingCDN/CloudFrontCustom NPM packages
Backend
Node.jsExpress.jsNestJS (modules, guards, interceptors, pipes, CQRS)RESTGraphQL (Apollo Federation)API designMicroservicesEvent-driven designWebSocketsKafkaRabbitMQBullTypeORMMongoose
Data
PostgreSQLMySQLMongoDBRedisElasticsearchDynamoDB
Cloud & DevOps
AWS (ECS, ECR, EC2, ELB, Lambda, S3, CloudFront, RDS, SQS, API Gateway, Route 53, IAM)DockerKubernetesCI/CD pipelinesGitHub ActionsTerraformNGINX
Testing & Observability
JestReact Testing LibraryPlaywrightCypressUnit testingIntegration testingE2E testingDatadog (APM, RUM, SLOs)PostHog
AI-Native Development
Claude Code (skills, subagents, hooks, MCP)CursorGitHub CopilotSpec-driven developmentPlan mode development
Practices
GitSystem designCode reviewTechnical design documents (TDDs)RFCs/ADRsSpikesAgile (Scrum, Kanban)On-call and incident commandMentoringTechnical hiring

Experience

VeVe (ECOMI)

Global digital collectibles marketplace (~250 employees, fully remote)

Sep 2021 – Present

Remote

Senior Full Stack Engineer, Marketplace & Payments
  • Project Waitlist (live-drop engine): Designed and built VeVe's live-drop engine from the ground up (NestJS GraphQL API, Redis virtual waiting room, Bull order queue), handling 180k concurrent collectors at 9,500 RPS and selling out 120k-item drops in under 4 minutes, with p99 checkout under 450 ms and zero oversells across 400+ drops.
  • Payments & payouts: Designed idempotent checkout and payout flows (idempotency keys, transactional outbox, deduplicating Kafka consumers) for digital collectibles, comics, digital wallets and bank payouts; took duplicate-charge incidents from 9 per quarter to 0 for 6 quarters while GMV grew 1.8x.
  • Search & discovery: Rebuilt search on Elasticsearch with a Kafka-fed indexing pipeline; p95 latency fell from 900 ms to 120 ms and search-to-purchase conversion rose 17% in a PostHog A/B test.
  • Next.js performance & SEO: Moved 60+ storefront routes to App Router with React Server Components and ISR; p75 Core Web Vitals improved in CrUX (LCP 3.8 s to 1.9 s, INP 380 ms to 140 ms, CLS 0.21 to 0.04) and organic sessions grew 41% in two quarters.
  • Design system: Co-created a typed React + Tailwind library (84 components, Storybook, axe checks in CI) used by 5 squads; cut UI build time for new features ~30% and closed 212 WCAG 2.2 AA issues.
  • Identity & KYC: Migrated 3.2M accounts to FusionAuth (OAuth 2.0/OIDC, MFA) with NestJS guards and role-based policies and zero forced logouts; a KYC integration cut median seller verification from 3 days to 11 minutes.
  • On-call & observability: Led incident command in a 3-timezone rotation and standardized Datadog APM, RUM and SLO dashboards; 20+ blameless postmortems drove action items that cut paging alerts 63%.
  • Delivery & reliability: Introduced trunk-based development, preview environments and Jest + Playwright gates in GitHub Actions, raising test coverage from 35% to 85%; deploys went from weekly to ~25/day, lead time from 4 days to 6 hours and change failure rate from 18% to 6%. Defined checkout SLOs (99.95% availability) and runbooks that cut MTTR from 95 to 38 minutes.
  • Growth features: Shipped promotions, affiliate attribution and a social activity feed (fan-out on write via SQS/Lambda); affiliates drove 12% of new-buyer acquisition within 3 quarters.
  • AI-native development: Built and rolled out a spec-driven development workflow on Claude Code, adopted by 22 engineers: shared CLAUDE.md context, 6 project skills, 4 review/test subagents, pre-commit hooks, MCP servers (GitHub, Playwright, Context7 and an internal Datadog/Jira server) and AI-assisted review gates. Median PR cycle time fell 45%, from 31 h to 17 h, with no rise in change failure rate.
  • Mentoring & cost: Mentored 7 engineers (3 promoted to senior), ran 90+ technical interviews and redesigned the full-stack hiring rubric; cut AWS spend $36k/year through ECS rightsizing, Graviton and CloudFront caching.

Cognizant (client: Verizon)

Enterprise telecom pricing & quote-automation platform

Jul 2020 – Jul 2021

Remote / Hyderabad, India

Lead Engineer (Full Stack)
  • Project Custom Pricing Portal: Led 5 engineers building a pricing and quotation portal from the ground up in React, TypeScript and Redux Toolkit within a micro-frontend architecture, integrated with backend pricing APIs; gradually launched with zero downtime for 1,200+ sales users.
  • Cut enterprise quote turnaround from 3 days to 4 hours with a rules-driven pricing configurator validating in real time against pricing APIs.
  • Brought frontend test coverage to 78% (Jest, React Testing Library, Cypress), reducing production UI defects 45% quarter over quarter; ran weekly async design reviews across India, UK and US teams.

Paytm (One97 Communications)

One of India's largest payment platforms (350M+ users)

Jun 2019 – Jun 2020

Noida, India

Full Stack Developer
  • Reduced the web bundle 38% (1.9 MB to 1.18 MB) via route-level code splitting and tree-shaking, taking p75 LCP on the payments flow from 4.1 s to 2.3 s.
  • Lifted bill-payment completion by 3.1% by rebuilding the checkout flow in React with optimistic UI, validations and accessible error states; built Node.js BFF endpoints that cut dashboard requests from 11 to 2.
  • Partnered with product managers and designers to ship accessible (WCAG 2.1 AA) payment screens and error-recovery states, cutting drop-offs by 8%.

Sparx IT Solutions

Product engineering agency

Dec 2016 – May 2019

Noida, India

Full Stack Engineer
  • Project CarDekho: Built listing, search and dealer-dashboard features (React, Node.js, Express, MySQL) for an automotive marketplace with 250k listings and 1,400 dealers; indexing and Redis caching cut search load from 2.8 s to 600 ms.
  • Project Apparel Design: Built a canvas-based in-browser design editor (layers, undo/redo, templates, print-ready PDF export) used by 30k+ small businesses in year one.
  • Delivered 9 client web and mobile apps, owning estimates, development, demos and handover docs.

Selected Open Source Projects

DateTime Picker for Google Sheets™

Open source

Google Workspace™ Marketplace add-on that adds the missing date and time picker to Google Sheets™: pick a date, time and time zone together and insert ISO 8601 into the selected cells. Built with Google Apps Script, GMT+0 by default with every IANA time zone supported.

mustkeemk.com/datetime-picker

Project Yo

Open source

Twitter-style backend in NestJS microservices (API gateway + Kafka event service) with MySQL/TypeORM, Redis/DataLoader caching, Elasticsearch search, DynamoDB notifications and S3 presigned uploads; CI/CD to AWS via GitHub Actions, Docker and Terraform.

github.com/mustkem/Twitter-Backend-NestJS

Project Hacker News SSR

Open source

Hacker News client with server-side rendering built from scratch in React, Express and Webpack (no SSR framework): Redux state hydrated from the server, code splitting with react-loadable, react-helmet SEO tags, XSS-safe state serialization and Jest/Enzyme tests.

github.com/mustkem/hacker-news-ssr

Education

B.Tech, Computer Science

APJ Abdul Kalam Technological University · Lucknow, India

2010 – 2014

Community

  • Stack Overflow contributor with 8,000+ reputation, answering JavaScript, React, Node.js and full-stack questions.
  • Recognized as top 1% talent worldwide by Upstack.