Marcin Sieradzki

Lead Software Engineer · AI Engineer · Design Engineer

Hi, I'm Marcin.I ship softwarewith AI agents.

I'm a lead software engineer in Copenhagen. I put AI agents into the software lifecycle and the design system, with checks and evals that make their work safe to ship.

6+ years at
  • Grundfos
  • Maersk
  • Wunderman Nordic
Marcin Sieradzki, smiling, wearing white headphones

Grab my face and pull. It springs back.

6+
years shipping production systems for large organisations
467+
UI repositories on the Maersk Design System, where I was the third-largest contributor
65
components in the Grundfos design system, where I'm the lead in a team of 5
18
components merged by my Component Factory, each in about 60 minutes
01 / Selected work

Software, and the factories that build it.

Agent pipelines inside the software lifecycle, the design systems they build from, and customer-facing products with millions of views a day. Built at Grundfos, Maersk and Wunderman, and in my own time.

8 agents0 / 8 projects built
  • validator
  • typecheck
  • build
  • runtime sweep
queued
Grundfos · 2025 to nowMy own idea

GDS Studio

Designers describe a UI. An agent builds the working prototype.

A desktop app where a designer writes a brief and an AI agent builds a working React prototype from real design system components and tokens, with its output streamed live. Designers take prototypes to stakeholder reviews without an engineer in the loop.

About 20
designers in the pilot
150
prototypes built
Minutes
instead of hours
  1. 1
    BriefA designer describes the UI in plain words.
  2. 2
    AgentBuilds from real components and tokens, in a sandbox with no network.
  3. 3
    System checkDecides the result, not the agent. The agent gets two fix rounds.
    validatortypecheckbuildruntime sweep
  4. 4
    PrototypeA working React prototype, streamed live while it is built.

Evals measure every release: 12 cases in dev and holdout sets. 1,100+ tests. 23 ADRs.

Own time · 2026Open source

Perron + Mylder

An open-source design system, and the live city map built on it.

Perron ships tokens, components and patterns with an MCP server, so coding agents can read the system directly. Mylder puts Copenhagen's buses, S-tog, metro and trains on one live map, and is honest about how fresh each position is. Built solo with coding agents.

54
components
14
patterns
280
tokens
4
languages
Reported 20 s ago
  • Live
  • Ageing
  • Estimated
  • Timetable only
  • No signal
Grundfos · 2025 to now

Software factory and Component Factory

Two agent pipelines inside the software lifecycle. A ticket goes in, and a human-reviewed pull request comes out. An agreed Figma component and its docs page go in, and a draft pull request with code, tests, stories and docs comes out.

18 components mergedabout 60 min each
Grundfos · Dec 2024 to now

Grundfos design system

Built from zero on React Aria, and machine-readable: a component registry, a token registry, and a validator that blocks unknown components and invented tokens.

65 componentsadoption around 70%
Maersk · 2021 to 2024

Maersk Design System

Framework-agnostic web components from one token source for 5 brands, light and dark, 3 densities. Third-largest contributor with 2,600+ commits, and I led the v1 to v2 upgrade.

70 components467+ repositories90% adoption
designsystem.maersk.com
Maersk · 2021 to 2024

Schedules on Maersk.com

One of the most visited pages on Maersk.com: routes, vessel schedules and port calls. Two brand builds, with an embeddable version of every view, and the page's first A/B experiments.

millions of views every dayVue 3
maersk.com/schedules
Maersk · 2021 to 2024

Vendor Master Data

Built the RESTful APIs and designed the UI on top of a ruleset engine that decides at runtime, per country and entity, which fields exist and how they validate. A delta engine shows approvers exactly what changed.

maker-checker approvals.NET APIs
Wunderman Nordic · 2020 to 2021

Micro-frontends

Re-architected a monolithic Vue 2 frontend into micro-frontends with Module Federation, so each team deploys on its own. Also built a KPI dashboard platform with a live campaign view over WebSockets.

35% smaller bundlesModule Federation
02 / Experience

Three stops so far.

Line M · Copenhagen · 2020 to now
  1. Jan 2020 to Nov 2021

    Wunderman Nordic

    Full-stack Developer

    • Micro-frontends with Module Federation: 35% smaller bundles, independent deployments per team.
    • KPI dashboard platform for email campaigns on Azure Functions.
    • Mentored two interns.
  2. Nov 2021 to Dec 2024

    A.P. Moller - Maersk

    Senior Software Engineer

    • Maersk Design System: 70 web components in 467+ repositories.
    • Schedules, with millions of views every day.
    • Vendor Master Data: APIs, ruleset UI and approval workflow.
    • Led technical interviews and mentored a junior developer to key contributor.
    • Early adopter of agentic development in a 10-person team.
  3. Dec 2024 to now

    Grundfos

    Lead Software Engineer

    • Lead in a team of 5 on a design system built from zero.
    • GDS Studio, the Component Factory, and a software factory: a ticket goes in, a human-reviewed pull request comes out.
    • Weekly design system adoption audit across 30 UI repositories, on local models.
  4. Next stop

    Your team?

    Open to lead, staff and senior software engineering roles where AI agents become part of how the team ships. Copenhagen or remote.

    Get in touch
03 / How I build

Agents are fast. Checks make them safe.

How I put agents into the software lifecycle: work comes in, agents build, checks decide, a person reviews. The work section above follows the same rules.

  1. Work comes in as a ticket, a design or a brief.

    The software factory takes a ticket. The Component Factory takes an agreed Figma component and its docs page. GDS Studio takes a designer's brief.

  2. One job per agent.

    Capture, research, architecture, code, tests, docs, accessibility, visual review. Small roles are easier to verify than one big prompt.

  3. The check decides, not the agent.

    After every pass a system check runs: validator, typecheck, build and a runtime sweep. The agent gets two fix rounds, then the check has the last word. Deterministic steps are scripts, not prompts.

  4. A person reviews. Every release is measured.

    The factories hand a person a pull request to review. An eval harness measures every GDS Studio release: programmatic graders first, then an LLM judge, on dev and holdout sets.

04 / About

One human, in the loop.

I'm a lead software engineer in Copenhagen with 6+ years of shipping production systems for large organisations.

I started in full-stack agency work at Wunderman Nordic, spent three years at Maersk on the design system and customer-facing products, and I'm now the lead in a team of 5 on the design system at Grundfos. That is where I put agents into the software lifecycle: factories that turn tickets and designs into pull requests for review, and a design system agents can build from.

My own projects, Perron and Mylder, are public and built solo with coding agents, so you can see how I work.

05 / Contact

Next stop: your team?

If you want AI agents working inside your software lifecycle and your design system, and someone to lead that work, I would like to hear about it.

marcin.sieradzki97@gmail.com

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