Amsterdam, Netherlands·Dutch national, fluent in English
25
years shipping web apps
100k+
live jobs on platform
~10×
YoY application growth
€40
a day cloud footprint
About
Hands-on technical leader with 25 years building cloud-based, user-facing web applications. The person clients and CEOs trust to walk into a struggling team, find what’s actually wrong and ship the fix.
The web has been the craft the whole time. Marcel builds on the platform and its standards, and he pays more attention to the person on the other end of the screen than to the org chart. He would rather ship the simple thing that works than a clever thing that doesn’t, and he keeps it that way: no extra weight until something actually needs it.
Comfortable owning architectural decisions that cut across teams, while staying close enough to the code to feel the consequences. Currently CTO of a bootstrapped Dutch HR-tech company he took from zero to 100,000+ live jobs and roughly 10× year-on-year application growth. It runs on TypeScript, Next.js, GCP and a production AI-augmented engineering practice.
Skills
Leadership
Engineering leadership
Cross-organisational influence
Trusted-advisor work
Hiring & team building
Technical strategy & roadmap
Staff/principal mentoring
Vendor & budget ownership
Technology
Web standardsBuilding on the open platform (HTML, CSS, the DOM) rather than framework-specific abstractions.developer.mozilla.org
Functional programmingComposing pure functions and immutable data instead of mutating shared state.en.wikipedia.org
TypeScriptJavaScript with static types, for safer code at scale.typescriptlang.org
ReactThe library for building user interfaces from components.react.dev
Next.jsThe React framework for production: SSR, routing and more.nextjs.org
Node.jsJavaScript runtime for building fast server-side apps.nodejs.org
Nest.jsOpinionated TypeScript backend framework built on Node.js.nestjs.com
React NativeBuild native iOS and Android apps using React.reactnative.dev
ExpoThe framework and platform for shipping React Native apps to the stores.expo.dev
Native iOS & Android apps
AWSAmazon Web Services, the largest cloud platform.aws.amazon.com
RedisIn-memory data store used for caching and queues.redis.io
DockerPackage apps into portable, reproducible containers.docker.com
Design patternsReusable, named solutions to recurring software-design problems.refactoring.guru
DSAData structures and algorithms: the fundamentals of organising data and solving problems efficiently.en.wikipedia.org
OOPObject-oriented programming: modelling behaviour as objects with state and methods.en.wikipedia.org
AI-augmented
LLMs (Gemini, Claude, GPT)
MCP servers
Claude CodeAnthropic’s agentic coding tool for the terminal.claude.com
GitHub CopilotGitHub’s AI pair-programmer.github.com
Machine learningTraining models on data to make predictions instead of hand-coding the rules.en.wikipedia.org
PythonThe lingua franca of data science and machine learning.python.org
scikit-learnThe standard Python library for classical machine learning.scikit-learn.org
NumPyThe array and numerical-computing foundation under most Python ML.numpy.org
CI/CD
TDDTest-driven development: write the failing test first.en.wikipedia.org
DDDDomain-driven design: model software around the business domain.en.wikipedia.org
Experience
CTO
Booming Jobs
Dec 2023 – present
Recruited by the founder to own technology end to end. Lead a team of 7 across engineering, design and architecture in a bootstrapped, profitable company. Dealroom named it one of the Top 100 Benelux Startups to Watch in 2025.
Took the core job platform from zero to production in 5 months as a team of 2, on a Next.js + Nest.js stack tight enough for two people to ship without thrashing. That MVP is still the foundation of the live product.
Built the LLM-powered job-feed service (BullMQ + Gemini on GCP) now hosting 100,000+ live jobs, replacing an editorial-only workflow.
Grew monthly applications ~10× year on year (1.2k to 11.5k over 12 months) on the back of feed quality and a Next.js SSR plus structured-data setup built with SEO specialists.
Shipped a cross-platform mobile app to the Apple App Store and Google Play, built in Expo / React Native in a few weeks alongside my day-to-day CTO responsibilities.
Run a production AI-augmented engineering practice: Claude and GitHub Copilot connected to the ticketing system via MCP, refining tickets, implementing against the monorepo and pushing to feature deployments with tests on the way. Engineers review every change in depth.
Engineering leadership
Technical strategy
Team building
AI-augmented engineering
MCPModel Context Protocol: the open standard connecting AI agents to tools and data.modelcontextprotocol.io
Claude CodeAnthropic’s agentic coding tool for the terminal.claude.com
GitHub CopilotGitHub’s AI pair-programmer.github.com
GeminiGoogle’s family of multimodal large language models.deepmind.google
Web standardsBuilding on the open platform (HTML, CSS, the DOM) rather than framework-specific abstractions.developer.mozilla.org
TypeScriptJavaScript with static types, for safer code at scale.typescriptlang.org
Next.jsThe React framework for production: SSR, routing and more.nextjs.org
Nest.jsOpinionated TypeScript backend framework built on Node.js.nestjs.com
React NativeBuild native iOS and Android apps using React.reactnative.dev
ExpoThe framework and platform for shipping React Native apps to the stores.expo.dev
TDDTest-driven development: write the failing test first.en.wikipedia.org
DDDDomain-driven design: model software around the business domain.en.wikipedia.org
Independent Consultant
six7.dev · Toptal (top 3%)
2020 – 2025
Senior freelance and Toptal engagements as tech lead, architect, principal engineer or trusted advisor. Clients brought me in for the code and usually kept me around for the harder problems that cut across their org.
Prym.de, tech lead and mentor. Modernised the GitLab monorepo of one of Germany’s oldest companies and made accessibility and SEO non-negotiable in the definition of done.
Decathlon NL, national tech lead. A team gutted by turnover; I steadied it by reframing the architecture conversation, then delivered a SvelteKit, GraphQL and Apollo proposal that was adopted as the go-forward plan.
ABN AMRO, frontend innovation lead. Interviewed developers across the org and surfaced structural problems management hadn’t seen, then got WCAG accessibility adopted across several teams.
MEP Amsterdam, architect and trainer. Set up the architecture for a Next.js and React web app that replaced a legacy codebase, and trained their team of C++ engineers into full-stack web developers. The software runs fully offline on air-gapped micro-computers aboard ships at sea and in the air.
Also: Nationale Postcode Loterij (platform strategy), StreamElements (creator CRM).
Tech lead
Trusted advisor
Cross-org influence
Mentoring
Team upskilling
Accessibility (WCAG)
Web standardsBuilding on the open platform (HTML, CSS, the DOM) rather than framework-specific abstractions.developer.mozilla.org
Next.jsThe React framework for production: SSR, routing and more.nextjs.org
SvelteKitThe application framework for Svelte.svelte.dev
A side project built with a friend: a searchable directory of curated web pages, categorised by industry and vetted by professionals in each field. I built the whole thing, front to back.
Designed and built the application solo, from the search and category model to the editor tooling the curators used.
Full-stack Next.js and TypeScript on a Postgres (via Knex) and MongoDB data layer, with Strapi as the content backend and DigitalOcean Spaces plus S3 for media.
Wrote Puppeteer crawlers and light NLP text processing to enrich and de-duplicate listings at scale.
Product & architecture
Solo full-stack
NLP (natural)A general natural-language-processing toolkit for Node.js.naturalnode.github.io
Next.jsThe React framework for production: SSR, routing and more.nextjs.org
ReactThe library for building user interfaces from components.react.dev
TypeScriptJavaScript with static types, for safer code at scale.typescriptlang.org
MantineA full-featured React component and hooks library.mantine.dev
Redux ToolkitThe official, batteries-included way to write Redux logic.redux-toolkit.js.org
NextAuthAuthentication for Next.js: providers, sessions and JWTs.authjs.dev
KnexA SQL query builder for Node.js across Postgres, MySQL and more.knexjs.org
MongoDBA document database for flexible, JSON-like data.mongodb.com
StrapiOpen-source headless CMS with an auto-generated API.strapi.io
AWS S3Amazon’s object storage for files and media at any scale.aws.amazon.com
PuppeteerHeadless-Chrome automation for scraping and rendering.pptr.dev
Node.jsJavaScript runtime for building fast server-side apps.nodejs.org
Senior Frontend Engineer & Architect
Theorem
Jul 2019 – Dec 2020
Senior consultant working with US west-coast clients from the Netherlands. Frontend architect and tech lead inside client teams; also part of Theorem’s hiring loop.
Apple. Shipped 5 greenfield projects in 12 months against an original scope of one, on a shared React, React Native, Svelte and Vue architecture. All five entered internal Apple Store use; one shipped publicly to Apple stores worldwide.
Couchbase. Joined as a code reviewer. The review turned up enough structural problems that I was kept on as architect for 6 months, shipped the dashboard rework ahead of schedule, then phased the consultants out cleanly.
Bloomberg. Built an internal React and TypeScript automation tool that replaced weeks of manual work per cycle. Bloomberg rarely works with outside agencies.
First American. Led two engagements and introduced ESLint-enforced WCAG safeguards as a baseline for a regulated industry.
Architecture leadership
Tech lead
Hiring loop
Accessibility (WCAG)
Web standardsBuilding on the open platform (HTML, CSS, the DOM) rather than framework-specific abstractions.developer.mozilla.org
ReactThe library for building user interfaces from components.react.dev
React NativeBuild native iOS and Android apps using React.reactnative.dev
SvelteA compiler-first UI framework with no virtual DOM.svelte.dev
TypeScriptJavaScript with static types, for safer code at scale.typescriptlang.org
Node.jsJavaScript runtime for building fast server-side apps.nodejs.org
GraphQLA query language for APIs: ask for exactly the data you need.graphql.org
a11y (accessibility)Accessibility (a11y): building so everyone can use it, to the WCAG standard.w3.org
CypressEnd-to-end testing framework that runs in the browser.cypress.io
Senior Frontend Engineer & Tech Lead
FrontMen
Sep 2016 – Jul 2019
Senior consultant placed with Dutch enterprises as architect, tech lead or frontend lead depending on the client’s need.
Tele2. Set up CI/CD and replaced a manual testing department for non-critical releases, which took releases from once every four months to several times a day. Built mijn.tele2.nl from scratch in React and Redux.
Elsevier / Mendeley. Shipped a Next.js SSR build for Mendeley Jobs that other teams adopted, and grounded org-wide WCAG adoption in live UX research with disabled users.
QuoMD. Architected a React web and React Native medical product, deployed on-site and validated with users at healthcare facilities. The product ran on medical models the team trained with home-grown Python machine-learning packages; I consumed their output in the app, which is where my ML and AI work goes back to.
Machine learningTraining models on data to make predictions instead of hand-coding the rules.en.wikipedia.org
PythonThe lingua franca of data science and machine learning.python.org
scikit-learnThe standard Python library for classical machine learning.scikit-learn.org
NumPyThe array and numerical-computing foundation under most Python ML.numpy.org
Web standardsBuilding on the open platform (HTML, CSS, the DOM) rather than framework-specific abstractions.developer.mozilla.org
ReactThe library for building user interfaces from components.react.dev
ReduxPredictable state container for JavaScript apps.redux.js.org
React NativeBuild native iOS and Android apps using React.reactnative.dev
Next.jsThe React framework for production: SSR, routing and more.nextjs.org
TypeScriptJavaScript with static types, for safer code at scale.typescriptlang.org
GraphQLA query language for APIs: ask for exactly the data you need.graphql.org
Node.jsJavaScript runtime for building fast server-side apps.nodejs.org
i18n (internationalisation)Internationalisation (i18n): building software that adapts to any language and locale.developer.mozilla.org
DockerPackage apps into portable, reproducible containers.docker.com
Principal Frontend Engineer
IceMobile
2013 – 2016
Led an international frontend team and migrated the stack from Ember.js to Polymer web components. Kick-started a Java-to-Node.js backend transition through an internal start-up spin-off.
Frontend Developer
Booking.com
2012 – 2013
Spotted a navigation dead-end in the hotel-booking flow and proposed the fix. It became one of the most valuable A/B tests Booking ran, and shaped how the flow kept users in context afterwards. Also built SEO landing pages at scale.
A/B testing
UX
SEO
Frontend
Frontend Developer & Designer
Topicus Healthcare
2008 – 2011
Full-stack on Java/Wicket clinical systems for GP posts, emergency care and other healthcare settings. Built an offline-capable web app with Google Gears that synced when reconnected, years before offline-first was common. Wrote an internal CSS framework and set the visual and UX design standards the teams built on. Cut an ER worklist load time from 30 seconds to under half a second.
Healthcare
Offline-firstApps built to run without a network, syncing when one returns. Here, air-gapped machines at sea and in the air.developer.mozilla.org
Marcel has built and shipped software as a contributor to Apple, Bloomberg, ABN AMRO, Decathlon, Couchbase, Booking.com and Elsevier. Former Apple, Bloomberg and ABN AMRO engineer.
Apple
Bloomberg
ABN AMRO
Decathlon
Couchbase
Booking.com
Elsevier
FAQ
Who is Marcel Hageman?
Marcel Hageman is a hands-on technical leader in Amsterdam, twenty-five years into building cloud-based, user-facing web applications and still writing code most weeks.
CTO of Booming Jobs today, with earlier turns as principal engineer, staff engineer and trusted advisor for the likes of Apple, Bloomberg, ABN AMRO, Couchbase and Decathlon.
CTO
Principal & staff engineer
Amsterdam
What is six7.dev, and where does the name come from?
It is the personal site of Marcel Hageman, a web developer and technical leader from the Netherlands. The name is a small puzzle: six letters in Marcel, seven in Hageman, and .dev for both Deventer, the Dutch town he grew up in, and the day job.
It also predates the “six seven” slang the kids use now. What that one means is anyone’s guess, and he is happy to assume they are all talking about him. Kindly, one hopes.
Marcel = 6
Hageman = 7
Deventer
Is Marcel available for fractional CTO, advisory or board work?
The CTO seat at Booming Jobs is the day job, and a small number of select advisory, fractional-CTO and board engagements fit alongside it. Remote by default, worldwide since 2018, across any timezone.
The engagements that suit him best are senior technical leadership: architecture, engineering strategy, team turnarounds and standing up an AI-augmented engineering practice.
Advisory
Fractional CTO
Board work
Remote, worldwide
Should a CTO still write code?
The short answer is yes. A leader who has drifted too far from the code ends up deciding things in the abstract, and the bill for that lands on the team.
Owning the architecture, the strategy and the cross-team calls while still reading and writing code keeps the cost of a decision felt rather than theorised. Twenty-five years hands-on is what makes it possible to drop into a stuck team and get it moving again.
Can Marcel help a struggling or slow engineering team?
Yes. Turning around struggling teams is the throughline of the whole career: brought in for the code, kept on to sort out the bigger things around it.
The method is unglamorous. Find what is actually broken, whether that is the architecture, the process, or how engineering and design talk to each other. Win the buy-in to change it. Leave the team shipping predictably again, and in better shape than he found it.
Turnarounds
Architecture
Process & delivery
What is an AI-augmented engineering practice?
It means putting AI coding agents into the real delivery pipeline, not treating them as a party trick. At Booming Jobs that runs in production: Claude and GitHub Copilot are wired to the ticketing system through MCP, refining tickets, implementing against the monorepo and pushing to feature deployments with tests along the way.
The point is to shorten the path from ticket to release without giving up code knowledge or ownership. Engineers still review every change in depth before it merges, so the team understands and owns what ships.
MCPModel Context Protocol: the open standard connecting AI agents to tools and data.modelcontextprotocol.io
Claude CodeAnthropic’s agentic coding tool for the terminal.claude.com
GitHub CopilotGitHub’s AI pair-programmer.github.com
Human review
How does Marcel prefer to work?
Leading a small, standalone expert team beats being one cog in a large org, every time. A handful of good people, run well, ship at a rate a much bigger group would struggle to match.
Remote-first, worldwide since 2018, so location and timezone rarely come into it. Underneath sits the discipline he insists on: TypeScript, TDD, DDD, strict typing and modern CI/CD.
Small expert teams
Remote-first
TDD & DDD
What technologies and areas does Marcel specialise in?
Day to day it is TypeScript, React, Next.js, Node.js and Nest.js on AWS and GCP, with deep frontend architecture across React, Svelte/SvelteKit and Vue. The preference is for web standards over framework lock-in, a leaning towards functional programming, and solid OOP, design-patterns and data-structures-and-algorithms fundamentals underneath it all.
A long-standing accessibility (a11y, WCAG) and internationalisation (i18n) advocate who has pushed adoption org-wide, running a production AI-augmented engineering practice on LLMs, MCP, Claude Code and GitHub Copilot.
TypeScriptJavaScript with static types, for safer code at scale.typescriptlang.org
React & Next.js
Web standardsBuilding on the open platform (HTML, CSS, the DOM) rather than framework-specific abstractions.developer.mozilla.org