Marcus Wilstrup
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Portrait of Marcus Wilstrup
Available for select engagements

Full Stack Ruby on Rails Developer

Marcus Wilstrup

Tech Lead, Investor & Advisor

Full Stack Ruby on Rails developer based in Copenhagen, building systems that scale and companies that last.

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Helping teams ship reliable Rails products and sustainable businesses.

About

About Marcus

Full Stack Ruby on Rails developer, tech lead, investor, and advisor.

What I Do

I'm a Full Stack Ruby on Rails developer and tech lead focused on building systems that scale and companies that last.

I work with teams to simplify architecture, reduce complexity, and ship outcomes that matter to the business.

Beyond Engineering

Alongside hands-on engineering, I invest in and advise ambitious companies, and perform technical due diligence for VCs.

I enjoy aligning stakeholders around clear goals and raising the bar for both product quality and engineering culture.

How I Work

  • Clear communication and outcome-driven roadmaps
  • End-to-end ownership from discovery to iteration
  • Simple designs and incremental improvements
  • Coaching teams and helping founders succeed

Services

How I Can Help

Available for select engagements with companies building products that matter.

Fractional CTO & Tech Leadership

Hands-on technical leadership for growing companies. I help simplify architecture, align teams around outcomes, and reduce costs while maintaining delivery velocity.

For: SaaS companies, marketplaces, B2B platforms
You get: Strategic direction, cost optimization, team alignment
Discuss your needs

Ruby on Rails Development

Expert Rails development for companies with mature applications. I specialize in scaling monoliths, reducing technical debt, and building features that drive revenue.

For: Product teams needing senior Rails expertise
You get: Clean code, faster shipping, sustainable architecture
Visit Nordium Labs

Technical Due Diligence

Rigorous technical assessment for investors. I evaluate teams, architectures, and technical risk to help VCs make confident investment decisions.

For: VCs, angel investors, acquiring companies
You get: Clear risk assessment, actionable insights
Request diligence

Experience

Experience

Recent roles and impact.

AB

Tech Lead & Full Stack Ruby on Rails Developer

Autobutler · Freelance

Current

  • Freelance tech lead helping Autobutler simplify architecture, reduce complexity, and maintain delivery velocity with a smaller team.
  • Contributed to reducing annual tech spend by 2M+ DKK while enabling multi‑million DKK savings through org and product simplification.
  • Aligned stakeholders around clear outcomes, created pragmatic migration paths, and supported a drastic positive impact on the bottom line.

Focus: Ruby on Rails, pragmatic architecture, product‑driven engineering, leadership

Previous

PC

Co‑founder & CTO

ProCollective · Startup

  • Co‑founded a freelance management platform used by companies such as Publicis Groupe.
  • Designed and evolved a Rails‑based product that supported both freelancers and large organisations.
  • Worked closely with customers to turn messy, real‑world workflows into simple product experiences.
  • Balanced speed of delivery with a pragmatic architecture that kept options open as the company grew.

Focus: Ruby on Rails, product development, stakeholder collaboration

UN

Senior Full Stack Developer

UNOIT · Full-time

Earlier

  • Built and maintained national‑scale education systems serving 2M+ Danish citizens.
  • Worked across the stack to deliver reliable, high‑impact software for municipalities and institutions.
  • Helped grow a business that was later acquired by EG, contributing to both product and technical success.
  • Learned how to operate large Rails codebases in production while keeping iteration speed high.

Focus: large‑scale platforms, long‑term maintainability, impact at national scale

Previous

MP

Product & Technology Advisor

Mindpool · Advisory

  • Advised on product and technology for Mindpool.
  • Supported a company journey that later resulted in an acquisition.

Focus: product & technology advisory, early‑stage companies

VC

Technical Due Diligence

VC · Advisory

Recent

  • Performed technical due diligence for a VC across early and growth‑stage opportunities.
  • Assessed products and codebases to support confident investment decisions.

Focus: technical due diligence, risk assessment, long‑term viability

View Full CV

Learning

Learning & Growth

How I keep improving as an engineer, tech lead, investor, and advisor.

Hands‑on experience at scale

Autobutler, UNOIT, ProCollective & more

Multiple sectors · consumer, B2B, and national‑scale systems

Most of my learning comes from building and operating real products in production — from national education platforms to automotive marketplaces and freelance management tools.

Continuous self‑directed learning

Books, code, and communities

Ongoing · curiosity‑driven

I learn best by building, reading, and talking to smart people — whether that's experimenting with new patterns in codebases, studying great companies, or sharing knowledge with other engineers.

Angel investing & advisory

Investor in SpaceX, Anduril, Groq, xAI & more

Small checks, early‑stage companies

I write angel checks in promising tech companies and advise early‑stage startups on product and technology. I also perform technical due diligence for VCs — fortunate to learn from world‑class teams.

Skills

Skills

Core strengths across Ruby on Rails, architecture, and technical leadership.

Core Stack

Ruby on Rails, Ruby, JavaScript

Ruby on Rails

Large monoliths, clear boundaries, fast iteration

Ruby

Pragmatic, expressive, maintainable code

JavaScript

Modern frontends supporting Rails backends

Architecture & Product

Pragmatic design, clear tradeoffs, migration paths

Architecture & design

Reducing complexity, drawing boundaries, keeping options open

Scalable Rails monoliths

Well‑structured monoliths over premature microservices

Outcome‑driven work

Shipping measurable business impact over tickets

Leadership & Operations

Tech leadership, diligence, and quality

Tech leadership

Aligning teams, simplifying roadmaps, raising the bar

Technical due diligence

Evaluating teams, codebases, and architectures for VCs

Quality & delivery

Continuous improvement, observability, and sustainable pace

Projects

Selected Projects

A few representative projects showcasing product impact and engineering depth.

Marketplace & operations

Autobutler platform evolution

Recent

Freelance tech lead helping Autobutler simplify its stack, reduce tech spend, and keep delivery velocity high with a leaner team.

  • • Reduced annual tech spend by 2M+ DKK while maintaining throughput.
  • • Enabled multi‑million DKK savings via org and product simplification.
Ruby on Rails Tech leadership Architecture
View
National-scale platform

Education systems for 2M+ citizens

UNOIT

Built and maintained national‑scale education platforms that later contributed to a successful acquisition by EG.

  • • Served 2M+ Danish citizens with reliable, high‑impact software.
  • • Balanced performance, maintainability, and complex stakeholder needs.
Full stack Public sector Long‑term systems
View
Startups & advisory

ProCollective, Mindpool & VC diligence

Ongoing

Co‑founded ProCollective, advised companies like Mindpool, and performed technical due diligence for VCs across early and growth‑stage opportunities.

  • • Helped companies clarify product vision and align technology with business outcomes.
  • • Partnered with investors to evaluate teams, architectures, and execution risk.
Advisory Investing Due diligence
View

Proven Impact

Results That Matter

Real outcomes from real projects — measurable impact on the bottom line.

Multi‑million DKK

in annual savings for Autobutler through infrastructure optimization, team rightsizing, and complexity reduction

11 → 4

engineers while maintaining velocity — demonstrating that smaller, focused teams ship faster

2M+

Danish citizens served by national education platforms — reliable systems at scale

UNOIT Exit

Work on national platforms contributed materially to UNOIT's successful acquisition by EG

Additional Outcomes

250+ schools adopted platforms I built and led development for at UNOIT

Enterprise clients including Publicis Groupe landed by ProCollective

1M+ users scaled to across automotive marketplace infrastructure

Drastic bottom‑line impact through cost discipline and pragmatic architecture

Contact

Ready to Ship Faster & Reduce Costs?

I help growing Rails companies and SaaS platforms reduce infrastructure costs, simplify architecture, and maintain velocity with leaner teams.

Fractional CTO services
Rails development
Technical due diligence
Email Marcus Connect on LinkedIn View GitHub