Carsten Behrens

Fullstack Developer

About

I'm a fullstack developer with 7 years of experience shipping products end-to-end for Otto, Gruner + Jahr, and Trusted Shops — and I specialize in frontend architecture and complex client-side applications.

Currently, I'm at Trusted Shops, where I build the consumer app for web, iOS, and Android.

I live and work in Hamburg, Germany.

Experience

  1. 2024 — Present

    Trusted Shops Senior Fullstack Engineer

    Built the Consumer Account platform, a cross-platform application for Web, iOS and Android serving 50,000+ monthly users, in a team of three — owning everything from the Flutter frontend to the Spring Boot and AWS backend. Designed and implemented a cross-platform push notification system end-to-end, from the AWS (SNS, SQS) and Firebase Cloud Messaging backend to the in-app notification UI in Flutter.

    • Dart
    • Java
    • Flutter
    • Spring Boot
    • AWS
    • Firebase

  2. 2021 — 2024

    Otto Fullstack Engineer

    Drove frontend development within a team of 5 engineers building OTTO Partner Connect, a partner platform serving 2,000+ partners on Vue.js and Spring Boot. Rebuilt a partner-facing analytics tool end-to-end with Nuxt 3 and Spring Boot, led the migration from JavaScript to TypeScript, and raised test coverage from 43% to 84% with E2E tests.

    • TypeScript
    • Java
    • Vue.js
    • Nuxt
    • Pinia
    • Spring Boot
    • AWS

  3. 2019 — 2021

    Gruner + Jahr Software Engineer

    Built a multi-tenant web application powering Gruner + Jahr's biggest editorial sites, including stern.de and brigitte.de, serving 6+ million monthly visitors. Introduced Real User Monitoring and worked with ad agencies on Core Web Vitals, cutting Largest Contentful Paint by 35% across all properties.

    • TypeScript
    • Handlebars
    • Web Components
    • Express

Skills

I'm a frontend-focused fullstack developer with 7 years of experience building applications end-to-end.

Throughout my career, I've worked across the stack — from Node.js and Spring Boot to React, Vue, and Flutter. Frameworks constantly evolve, so I focus my energy on the software design principles underneath them rather than memorizing syntax. That foundation lets me adapt quickly and choose the best tool for the problem at hand.

“It is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.”
— Abraham Maslow

In my last two roles, applying that philosophy meant spending about 70% of my time on the frontend and 30% on the backend — a split that flips whenever my team needs it to. I'm comfortable taking a feature the whole way: setting up the infrastructure in Terraform, building the service in Spring Boot, shipping the UI in React.

The frontend is where I go deepest. I love building complex, interactive client-side applications — the kind with real state to manage — and I care about keeping them tested and maintainable long after the first release.

Technologies I've worked with, past and present

  • TypeScript
  • JavaScript
  • Vue.js
  • React
  • Redux
  • Next.js
  • Remix
  • Nuxt
  • Pinia
  • Node.js
  • Express
  • Java
  • Spring Boot
  • GraphQL
  • Kotlin
  • Flutter
  • Dart
  • Firebase
  • MongoDB
  • MySQL
  • AWS
  • Docker
  • Terraform
  • GitHub Actions
  • Cypress
  • Jest
  • Git
  • HTML5
  • CSS3
  • Sass
  • Tailwind CSS
  • Vite

Projects

  • Boom Bap Sampler & Step Sequencer

    A browser-based sampler, step sequencer, and drum machine. Load samples, slice them up, program beats on a grid, and hear the pattern play back in real time — all triggered and scheduled in the browser.

    • TypeScript
    • React
    • Tone.js
    • WaveSurfer
    • Zustand
    • Tailwind

Contact

Got a role or a project in mind? Email's the best way to reach me.

carsten@carstenbehrens.com

You can also find me on GitHub and LinkedIn.