About me.

For me, being a Technical Product Owner means understanding both sides of the job. First what we should build and second what it takes to build it. I don’t need to make every technical decision myself, but I want to understand the consequences well enough to question assumptions, prioritise properly and work closely with engineering.

How I got here.

I'm Marius Kalder, with 10 years of experience across digital platforms, product delivery and IT transformation in B2B and B2C environments.

My work combines product strategy, architecture alignment and cross-functional delivery. I progressed IT Consulting into Product Ownership for multiple web, Android and iOS delivery streams, then to leading the product side of a live e-commerce microfrontend migration, and later to strategic IT portfolio management for digital Help Center initiatives — including budget planning, executive decision support and AI proof-of-concepts.

My technical fluency is grounded in hands-on practice with JavaScript, Node.js, PostgreSQL, Linux and self-hosted infrastructure. It helps me assess technical constraints, ask sharper questions and make informed trade-offs with architects and engineering teams. Most recently I have designed and self-hosted this portfolio as a working product, not just a page. I genuinely love solving problems and building products with a purpose.

Experience map

What I bring to the work.

Since 2016, I’ve worked as an IT Consultant, Business Analyst, Project Manager, Product Owner and Portfolio Manager. The roles were different, but I kept dealing with the same questions: What problem are we solving? What can we actually deliver? And what should we do next?

IT Consultant + Business Analyst

  • Product direction

    Developed the product vision for an editor tool at BWI, built for the German Ministry of Defence.

    Product vision
  • Build-ready requirements

    Wrote the epics, user stories and acceptance criteria myself for a variety of products (1&1 Deposit Shop, E.ON E-Commerce, GMX/web.de, Mein02, AlidTalk etc.).

    Epics
    User Stories
    Acceptance criteria
  • Security by design

    Captured security requirements for hosting on user devices and protecting backend systems in a government context.

    Security Requirements
  • Requirements archaeology

    Reconstructed five-year-old, undocumented requirements for 1&1’s deposit shop from stakeholder interviews, production code and legacy records.

    Requirements archaeology
    Requirements engineering

Project Manager

  • Migration delivery

    Led the microfrontend migration of 1&1’s deposit shop, reconstructing five-year-old requirements from interviews and legacy code.

    Microfrontend
  • Cross-functional coordination

    Coordinated web, iOS, Android, QA, Legal, Security, Marketing and Design teams through that migration.

    Delivery Leadership
  • Release ownership

    Owned releases for the 1&1 Deposit shop, E.ON wallbox shop, GMX/web.de as well as MeinO2 plus Partner Applications apps.

    Release Management
  • System integration

    Connected the Mein O2 app with the Box 7 backend and Telefónica’s MCE API gateway..

    REST
    JSON
  • Explicit trade-off

    Chose to build E.ON’s e-mobility shop on the existing legacy system rather than a clean rebuild — trading a faster launch for added technical debt.

    Time to market
    Technical debt

Product Owner + Portfolio Manager

  • Roadmap ownership

    Owned roadmaps across O2 (including ALDI TALK), GMX/web.de, BWI, the E.ON wallbox shop and 1&1’s microfrontend platform.

    Roadmaps
    Product Ownership
  • Architecture context

    Worked with microfrontend and service-based architecture during the 1&1 deposit-shop migration.

    Architecture
  • Value-based prioritization

    Prioritised backlogs using MoSCoW, strictly ranked by business value.

    Time to market
    Release Strategy
  • Portfolio clarity

    Reduced an unstructured 25-ticket IT portfolio to 14 scoped initiatives with budget and timeline.

    Portfolio Management
  • Stakeholder and AI initiatives

    Aligned C-level stakeholders for the Digital Help Center; initiated an AI chatbot PoC for 1&1 and built VoCaBi, an LLM-powered translation app.

    Generative AI
    AI product discovery

Working principle

How I make product decisions.

I need to understand both the user problem and how the product is built and operated. My job as a Product Owner is to make sure we build the right thing. That means understanding technical decisions, asking the right questions, prioritising well and working closely with developers and architects.

When I'm not working.

I train motogymkhana — precision motorcycle riding at low speed, where physics, balance and repetition decide the outcome. It's the perfect counterpart to my professional mindset: structured practice, clean execution, continuous improvement — the same principles, just on two wheels instead of in a sprint review.

When I’m not in Germany, I spend much of my time travelling, especially through Southeast Asia. Thailand in particular has become a place to slow down and reflect a bit like a retrospective, just with better food and a much better view.

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