Staff Fullstack & AI Engineer

Engineering ProductsFrom Zero To Scale

Hi, I'm Tugay, your Designer, Engineer, Architect, Tester, Mentor, Leader, Innovator, AI Engineer

11+ years turning ideas into enterprise products that scale.

agent.tsLayersDesignCardButtonTugay$pnpm test && pnpm build✓ 128 tests passedvite building for production…✓ built in 1.2sdeploy0%OrderPayInvoiceauth › signs in with SSOcart › applies voucherrag › cites its sourcesagent › blocks unsafe toolsapi › answers in 80 ms0 passedcoverage0%src/hooks/useCart.ts const [items, setItems] =- useEffect(() => fetch(url))+ const { data } = useQuery(cart)+ return { items: data ?? [] }}TugayNice, much cleaner!✓ ApprovedTO DOIN PROGRESSDONEAuth SSORAG searchCheckoutDesign QAvelocity0 ptsepoch 0/3loss 2.41eval score0.00awaitcreateAgent({model:'gpt-4o',tools:[search,mcp],memory:rag('docs'),}).ship();LLMRAG
  • AI Engineering
    • AI agents & copilots
    • RAG systems & enterprise search
    • LLM fine-tuning (LoRA/QLoRA)
    • Internal process automation
    • Agentic workflows & MCP
  • Product Development
    • Frontend: React, Next.js, Angular, Vue
    • Backend: Node.js, Go, Python
    • Microservices & APIs
    • Testing & CI/CD
    • Performance optimisation
  • Architecture & Leadership
    • Zero-to-one products
    • Legacy migrations
    • Design systems
    • Cloud & Kubernetes
    • Interim tech lead
  • Team Extension
    • Specialists per discipline: FE, BE, DevOps, UI/UX, QA, PM
    • Up to 31 people across 3 projects
    • One accountable lead: me
    • Remote, B2B contracts
  • Cloud Infrastructure
    • AWS, Microsoft Azure & Hetzner
    • Docker & Kubernetes
    • Cloudflare at the edge
    • CI/CD with GitHub Actions & Azure DevOps
  • Mobile Engineering
    • React Native apps for iOS & Android
    • App performance & stability
    • Admin platforms behind the app
  • Software Testing
    • Unit tests with Jest
    • E2E tests with Playwright & Cypress
    • Test automation in CI/CD
    • Review and testing of AI-generated code

Professional Snapshot

For over 11 years I have taken products from zero to scale as a freelance technical lead, for enterprise and consumer businesses in events, insurance, SEO, e-commerce, affiliate marketing, luxury fashion, furniture, education, telecom and healthcare.

I own the full product lifecycle, from design and architecture to testing, deployment and monitoring, and lead remote, cross-functional teams of up to 31 people across three parallel projects.

Today I also build the AI inside the products: agents, RAG systems and fine-tuned LLMs on Azure that run in enterprise production environments, plus an agentic engineering workflow that ships faster without lowering the bar.

Ideas & Business GoalsTransformed IntoProducts That Scale

Work Experiences

  1. Incoqnito GmbH

    Fullstack Developer

    Jan 2015 – Sep 2019

    Hannover

    250+dialysis centres, 99.9% uptime
  2. Cassis Media GmbH

    Lead Fullstack Engineer

    Sep 2019 – May 2021

    Ratingen · Freelance

    36Kapp downloads (Snapify)
  3. Neimu

    Project Management Lead & Senior Developer

    Feb 2020 – Mar 2021

    Ho Chi Minh City

    0 → 1inventory system connecting all suppliers
  4. Compado GmbH

    Senior Frontend Engineer

    May 2021 – May 2023

    Berlin

    €10M+annual revenue in 2022
  5. 1&1 Telecommunication SE

    Senior Frontend Engineer

    May 2023 – Sep 2023

    Karlsruhe · Freelance

    −40%development time across 5 products
  6. Interwetten Ltd.

    Lead Frontend Engineer

    Sep 2023 – Mar 2024

    Vienna · Freelance via Kapsys GmbH

    94 / 100PageSpeed mobile / other categories
  7. Teamstack GmbH

    Lead Frontend & AI Engineer

    Sep 2023 – Jan 2025

    Vienna · Freelance via Kapsys GmbH

    €1.1Myearly revenue product (Seobase)
  8. Kapsys GmbH

    Fullstack Engineer

    Jan 2025 – Jun 2026

    Vienna · Freelance

    −35%administration time
  9. mars agency GmbH

    Staff Fullstack & AI Engineer

    Mar 2021 – Present

    Frankfurt · Freelance, full-time

    13,000+events a year on the platform I built
  1. Work Experiences

    Cassis Media GmbH

    Lead Fullstack Engineer

    Sep 2019 – May 2021

    Ratingen · Freelance

  2. NeimuLed the team that launched the online shop and built the inventory system behind it.

    Neimu

    Project Management Lead & Senior Developer

    Feb 2020 – Mar 2021

    Ho Chi Minh City

  3. Compado GmbH

    Senior Frontend Engineer

    May 2021 – May 2023

    Berlin

    CompadoWix-like low-code page editor powering 1,000+ comparison websites.
  4. 1&1Design-system POC on web components, reused across 5 products.
  5. Interwetten Ltd.

    Lead Frontend Engineer

    Sep 2023 – Mar 2024

    Vienna · Freelance via Kapsys GmbH

    InterwettenMicro-frontend blog platform with thousands of multilingual, multi-licence pages.
  6. TeamstackAngular-to-Next.js migration of the SEO platform Seobase, plus its multi-agent LLM system and AI inference services.

    Teamstack GmbH

    Lead Frontend & AI Engineer

    Sep 2023 – Jan 2025

    Vienna · Freelance via Kapsys GmbH

  7. Kapsys GmbH

    Fullstack Engineer

    Jan 2025 – Jun 2026

    Vienna · Freelance

    KapsysMicroservices CRM for a Swiss insurance broker, behind its client app.
  8. mars agencyBuilt the attendance platform from scratch as lead developer and now develop the AI inside it: agents, RAG and model optimisation for 300K users.

    mars agency GmbH

    Staff Fullstack & AI Engineer

    Mar 2021 – Present

    Frankfurt · Freelance, full-time

  9. Your next product, from idea to scale.

    I join as a freelance tech lead or AI engineer and take ownership from the first concept to production.

    Let's talk about your project →

    Previously built for

    • mars agency GmbH
    • Kapsys GmbH
    • Interwetten Ltd.
    • 1&1 Telecommunication SE
    • Compado GmbH
    • Neimu
    • Incoqnito GmbH

part-time at Cassis Media GmbH in parallel as Lead Fullstack Engineer

part-time at mars agency GmbH in parallel as Staff Fullstack Engineer

Stack & Skills

Hover over a skill to see how long and where I've used it.

AI22 skills

  • Generative AI

    • Mistral3+ years experienceProjectsmars agency
    • Llama 32+ years experienceProjectsmars agency
    • LangChain
    • LlamaIndex
    • MCP2+ years experienceProjectsmars agency
    • Copilot Studio3+ years experienceProjectsmars agency
  • Techniques

    • RAG3+ years experienceProjectsmars agency
    • Fine-tuning (LoRA/QLoRA)3+ years experienceProjectsmars agency
    • Agentic Workflows2+ years experienceProjectsmars agency
    • Prompt Engineering3+ years experienceProjectsmars agency
  • AI platforms

    • Azure OpenAI3+ years experienceProjectsmars agency
    • Azure AI Foundry3+ years experienceProjectsmars agency
    • Azure AI Search3+ years experienceProjectsmars agency
    • Azure ML
    • AWS Bedrock
  • AI Infrastructure

    • PyTorch3+ years experienceProjectsmars agency
    • Hugging Face3+ years experienceProjectsmars agency
    • ONNX3+ years experienceProjectsmars agency
    • TensorRT3+ years experienceProjectsmars agency
  • Agentic Coding

    • Claude Code1+ year experienceProjectsmars agency
    • Codex
    • GitHub Copilot

Design4 skills

  • UI & UX

    • Figma< 1 year experienceProjectsInterwetten
    • Adobe XD1+ year experienceProjectsNeimu
  • Modelling

    • UML5+ years experienceProjectsNeimu · Incoqnito
    • BPMN1+ year experienceProjectsNeimu

Languages15 skills

  • Programming

    • Scripting
      • Bash
      • JavaScript11+ years experienceProjectsAll projects
      • TypeScript10+ years experienceProjectsmars agency · Kapsys · Teamstack · Interwetten · 1&1 · Compado · Neimu · Incoqnito
    • General purpose
      • Python3+ years experienceProjectsKapsys · Teamstack · Neimu
      • Go1+ year experienceProjectsmars agency
      • Rust1+ year experienceProjectsCassis Media
      • Ruby2+ years experience
      • C++
      • C#4+ years experienceProjectsIncoqnito
  • Markup

    • HTML11+ years experienceProjectsAll projects
    • Markdown11+ years experienceProjectsAll projects
    • XML
  • Style sheets

    • CSS11+ years experienceProjectsAll projects
    • Sass4+ years experienceProjectsIncoqnito
  • Query

    • SQL6+ years experienceProjectsNeimu · Cassis Media · Incoqnito

Frontend19 skills

  • General

    • HTML11+ years experienceProjectsAll projects
    • CSS11+ years experienceProjectsAll projects
  • Frameworks

    • Next.js3+ years experienceProjectsmars agency · Teamstack · Interwetten
    • React Native1+ year experienceProjectsNeimu · Cassis Media
    • Angular2+ years experienceProjectsKapsys · Teamstack
    • Vue.js2+ years experienceProjectsCompado
    • Tailwind CSS1+ year experienceProjectsmars agency
    • Phaser 3
  • Libraries

    • React11+ years experienceProjectsmars agency · Teamstack · Interwetten · Neimu · Cassis Media · Incoqnito
    • D3.js5+ years experienceProjectsNeimu · Incoqnito
    • Three.js
    • Zustand< 1 year experienceProjectsInterwetten
    • Redux11+ years experienceProjectsmars agency · Neimu · Cassis Media · Incoqnito
    • TanStack Query2+ years experienceProjectsCompado
  • UI libraries

    • Bootstrap4+ years experienceProjectsIncoqnito
    • Material UI1+ year experienceProjectsNeimu · Cassis Media
    • shadcn/ui2+ years experienceProjectsmars agency · Interwetten
  • Tools

    • Storybook6+ years experienceProjectsInterwetten · 1&1 · Compado · Incoqnito
    • Stencil.js2+ years experienceProjects1&1 · Compado

Backend21 skills

  • Frameworks

    • Express.js5+ years experienceProjectsNeimu · Incoqnito
    • NestJS5+ years experienceProjectsmars agency
    • FastAPI1+ year experienceProjectsNeimu
    • Django1+ year experienceProjectsKapsys
    • Rails2+ years experience
    • Actix Web1+ year experienceProjectsCassis Media
    • .NET4+ years experienceProjectsIncoqnito
  • APIs

    • REST10+ years experienceProjectsKapsys · Interwetten · Compado · Neimu · Cassis Media · Incoqnito
    • GraphQL9+ years experienceProjectsmars agency · Incoqnito
    • Apollo3+ years experienceProjectsIncoqnito
    • tRPC
    • gRPC1+ year experienceProjectsNeimu
    • WebSockets6+ years experienceProjectsNeimu · Cassis Media · Incoqnito
    • OpenAPI
    • Webhooks1+ year experienceProjectsNeimu
  • Microservices

    • RabbitMQ5+ years experienceProjectsmars agency
    • Kafka4+ years experienceProjectsIncoqnito
  • ORM / ODM

    • Prisma1+ year experienceProjectsNeimu
    • Mongoose
  • Auth

    • OAuth 2.04+ years experienceProjectsIncoqnito
    • JWT6+ years experienceProjectsInterwetten · Neimu · Incoqnito

Tools12 skills

  • Build tools

    • Webpack8+ years experienceProjectsInterwetten · Compado · Neimu · Cassis Media · Incoqnito
    • Turbopack1+ year experienceProjectsmars agency
    • Vite< 1 year experienceProjectsInterwetten
    • Babel8+ years experienceProjectsInterwetten · Compado · Cassis Media · Incoqnito
  • Runtimes

    • Node.js11+ years experienceProjectsmars agency · Interwetten · Neimu · Incoqnito
    • Bun
    • Deno
    • Edge Runtime< 1 year experienceProjectsInterwetten
  • IDEs

    • VS Code11+ years experienceProjectsAll projects
    • Antigravity
  • Delivery

    • Jira8+ years experienceProjectsInterwetten · Compado · Neimu · Cassis Media · Incoqnito
    • Scrum8+ years experienceProjectsInterwetten · Compado · Neimu · Cassis Media · Incoqnito

Data12 skills

  • Databases

    • PostgreSQL5+ years experienceProjectsNeimu · Incoqnito
    • MySQL1+ year experienceProjectsCassis Media
    • MongoDB5+ years experienceProjectsmars agency · Compado
    • Cosmos DB
    • Pinecone
    • Weaviate
  • Storage

    • Redis2+ years experienceProjectsCompado
    • AWS S36+ years experienceProjectsCompado · Incoqnito
  • CMS

    • WordPress
    • Strapi< 1 year experienceProjectsInterwetten
    • Kontent.ai< 1 year experienceProjectsInterwetten
    • Sanity2+ years experienceProjectsCompado

Testing21 skills

  • Unit

    • Jest4+ years experienceProjectsInterwetten · Compado · Neimu · Cassis Media
    • Jasmine4+ years experienceProjectsIncoqnito
  • E2E

    • Playwright2+ years experienceProjectsInterwetten · Compado
    • Puppeteer1+ year experienceProjectsNeimu · Cassis Media
    • Cypress2+ years experienceProjectsInterwetten · Incoqnito
    • Nightwatch
  • Performance

    • Lighthouse3+ years experienceProjectsInterwetten · Compado · Neimu
    • PageSpeed Insights8+ years experienceProjectsInterwetten · Compado · Neimu · Incoqnito
    • Bundle analysis8+ years experienceProjectsCompado · Neimu · Cassis Media · Incoqnito
    • Load testing4+ years experienceProjectsIncoqnito
    • Stress testing6+ years experienceProjectsCompado · Incoqnito
    • Spike testing1+ year experienceProjectsNeimu
    • Cache hit rates
    • Memory leak detection1+ year experienceProjectsNeimu
  • Accessibility

    • eslint-plugin-jsx-a11y
    • cypress-axe
    • @axe-core/playwright2+ years experienceProjectsInterwetten · Compado
    • jest-axe1+ year experienceProjectsInterwetten · Neimu
  • Security

    • SAST4+ years experienceProjectsIncoqnito
    • DAST4+ years experienceProjectsIncoqnito
  • Experiments

    • A/B Testing2+ years experienceProjectsInterwetten · Compado

Cloud10 skills

  • AWS

    • IAM10+ years experienceProjectsmars agency · Kapsys · Compado · Incoqnito
    • EC2
    • VPC
    • Load Balancer
    • Lambda5+ years experienceProjectsmars agency · Compado
    • API Gateway2+ years experienceProjectsCompado
    • CloudFront2+ years experienceProjectsCompado
    • CloudWatch6+ years experienceProjectsCompado · Incoqnito
  • Other providers

    • Hetzner1+ year experienceProjectsCassis Media
    • Microsoft Azure8+ years experienceProjectsmars agency · Incoqnito

DevOps18 skills

  • Hosting & edge

    • Vercel
    • Cloudflare4+ years experienceProjectsmars agency · Interwetten · Compado
    • Netlify
    • Heroku1+ year experienceProjectsNeimu
  • Containers

    • Docker11+ years experienceProjectsmars agency · Teamstack · Compado · Cassis Media · Incoqnito
    • Kubernetes7+ years experienceProjectsmars agency · Teamstack · Interwetten · Incoqnito
  • IaC

    • Terraform2+ years experienceProjectsCompado
    • CloudFormation6+ years experienceProjectsCompado · Incoqnito
  • Web servers

    • NGINX1+ year experienceProjectsCassis Media
    • Apache4+ years experienceProjectsIncoqnito
  • CI/CD

    • GitHub Actions7+ years experienceProjectsmars agency · Interwetten · Compado · Neimu · Cassis Media
    • GitLab CI/CD
    • CircleCI
    • Azure DevOps4+ years experienceProjectsIncoqnito
    • Jenkins< 1 year experienceProjectsInterwetten
  • Monitoring

    • Sentry< 1 year experienceProjectsInterwetten
    • New Relic2+ years experienceProjectsCompado
    • Grafana1+ year experienceProjectsNeimu · Cassis Media

3rd party16 skills

  • Payments

    • Stripe5+ years experienceProjectsmars agency
    • PayPal1+ year experienceProjectsNeimu
    • Klarna1+ year experienceProjectsCassis Media
  • Authentication

    • Auth01+ year experienceProjectsKapsys
    • Clerk
  • Email

    • Resend
    • Mailtrap
  • Messaging

    • Twilio1+ year experienceProjectsNeimu · Cassis Media
    • Slack3+ years experienceProjectsInterwetten · Compado · Neimu
  • Analytics

    • Google Analytics4+ years experienceProjectsInterwetten · Compado · Neimu · Cassis Media
    • Google Tag Manager4+ years experienceProjectsInterwetten · Compado · Neimu · Cassis Media
  • Maps

    • Google Maps Platform
  • BaaS

    • Supabase< 1 year experienceProjectsNeimu
  • CRM

    • Salesforce
  • Compliance

    • Eyeable1+ year experienceProjectsNeimu
    • Cookiebot3+ years experienceProjectsInterwetten · Compado · Neimu

Character

Creative: 99%, Communicative: 85%, Detail-oriented: 95%, Eager to learn: 85%, Independent: 90%CreativeCommunicativeDetail-orientedEager to learnIndependent

How I Work

  • Impact & Results

    I measure success in business outcomes: revenue, time saved, users served. Zero-to-one businesses that scale, not features for the drawer.

  • Quality & Testing

    Test strategies, automation and high release success rates. I bring the same rigour to AI: agent-generated code and AI features are reviewed and tested before they reach users.

  • Architecture & Docs

    Scalable, robust systems, from microservices to AI-ready platforms, with documentation and migration guides so no knowledge silos remain.

  • Mentoring & Remote Teams

    I train and mentor engineers, including how to work well with coding agents, and build remote cultures of continuous improvement and cross-functional collaboration.

At the end of the day, what matters most is making a big impact on projects efficiently, and AI is now the biggest lever for that.

— Tugay Serinken

Let's build something together!

Get In Touch