I build things
for the web
& occasionally
break them

Senior Software Engineer with 10+ years of making pixels behave and servers respond. Currently scaling checkout flows for 30M+ users at Kaufland e-commerce.No websites were harmed in the making of this portfolio. Okay, maybe one.

See my work ↓Get in touch
~ cat about.json
{
  "name": "Denis Shtabnoy",
  "location": "Berlin, DE",
  "role": "Senior Software Engineer",
  "coffee_today": 3,
  "mass_produced_bugs": 0,
  // ^^ technically unverifiable
  "stack": ["React", "Vue", "TS",
    "Node", "Python", "Postgres"],
  "open_to_work": true
}
~
ReactTypeScriptVue.jsNode.jsNext.jsPostgreSQLDockerPythonGraphQLRedisAWSTailwindn8nAI toolsCypressPlaywrightReactTypeScriptVue.jsNode.jsNext.jsPostgreSQLDockerPythonGraphQLRedisAWSTailwindn8nAI toolsCypressPlaywright
// about

The short version

I've been building for the web since 2016, starting with AngularJS and real-time geo-visualization in Russia, then moving to Stockholm where I shipped products at Daniel Wellington, Fyndiq, and Warner Bros. Discovery. Now I'm in Berlin, scaling frontend systems at Kaufland e-commerce — one of Germany's biggest online marketplaces.

I care most about the intersection of developer experience and user impact: clean architecture that ships fast, checkout flows that convert, and performance budgets that get respected. I'm currently deep-diving into backend engineering, AI automation, and system design because I believe the best engineers in 2026 own the full stack.

When I'm not coding, I'm probably reading self-help books (at least 2.5 so far) or giving unsolicited life advice to friends who didn't ask for it.

10+
Years of experience
and still Googling CSS flexbox
30M+
Monthly users served
at current job alone
50K+
Daily transactions
checkout flow I own
8
European markets
and counting
// projects

Things I've built (that I'm allowed to show)

In progress
taskflow-api
Production-grade REST API for task management. JWT auth, role-based access, PostgreSQL with Prisma, Redis caching, rate limiting, full test coverage. My backend architecture showcase.
TypeScriptExpressPostgreSQLPrismaRedisDocker
Coming soon
AI document analyzer
Full-stack SaaS app: upload documents, get AI-powered analysis, summaries, and insights. Next.js frontend, Node.js API, OpenAI integration, vector database for semantic search.
Next.jsNode.jsOpenAI APIPineconeVercel
In progress
leetcode-solutions
Curated algorithm solutions in TypeScript and Python with detailed complexity analysis, approach explanations, and pattern categorization. Because interviews are still a thing.
TypeScriptPythonAlgorithms
Coming soon
n8n AI workflows
Collection of production-ready AI automation workflows: RAG pipelines, intelligent email classifiers, Slack bots with memory, and webhook-driven data processors.
n8nLangChainOpenAIPython
Live
33 by 33
33 things to do before turning 33. A personal project tracking goals and milestones — built with Next.js and React Query.
Next.jsReact QueryTypeScript
// experience

Where I've left my mark (and git history)

2025 — Present
Kaufland e-commerce
Software Engineer, Frontend
Scaling frontend for 30M+ MAU across 8 markets. Own the checkout flow processing 50K+ daily transactions. Reduced LCP by 25%, improved checkout conversion by 12% through A/B testing. Integrated Adyen, Apple Pay, Google Pay.
2022 — 2024
Warner Bros. Discovery
Senior Software Engineer
Architected 10+ React back-office apps used by 500+ internal users. Built a design system with 60+ components. Increased code coverage from 45% to 85%, reducing production bugs by 50%.
2021 — 2022
Fyndiq (CDON Group)
Frontend Developer
Built features for a marketplace with 2M+ products. Reduced page load by 30%. Created a reusable component library and coding standards.
2019 — 2021
Daniel Wellington
Web Developer
Led Angular-to-React migration across 4 apps, reducing bundle size by 35%. Introduced GraphQL, cutting data fetching time by 50%. Built a 40+ component UI library with Storybook.
2016 — 2019
Starflow · Luxoft · Angstrem
Full-Stack / Frontend Developer
Built platforms with React, React Native, Node.js, PostgreSQL. Created real-time geo-visualization rendering 10K+ data points. Where the journey began.
// contact

Let's build something

I'm open to remote opportunities — especially if your team ships fast, cares about craft, and doesn't do "quick syncs" that last 45 minutes.

EmailLinkedInGitHub