Marcus Wilstrup
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Curriculum Vitae

Marcus Wilstrup

Full‑stack Ruby on Rails developer and tech lead with a track record of simplifying systems, improving delivery, and driving tangible business outcomes.

Marcus Wilstrup

Experience

Freelancer

Tech Lead / Software Developer

Copenhagen • March 2022 - Present

Freelancing as Tech Lead for Autobutler while taking on short-term contracted development projects. Sometimes I do technical due diligence for VCs. I also build and maintain my own products.

Autobutler

Tech Lead / Software Developer

Copenhagen • April 2021 - February 2022

Full Stack lead Ruby on Rails developer, with responsibility for a small dev team and many projects including a large Ruby on Rails monolith, multiple microservices written in Ruby, Elixir & Phoenix, and an SPA React app.

  • Reduced annual tech spend by 2M+ DKK via infrastructure optimization and cost discipline
  • Maintained delivery velocity while rightsizing engineering from 11 → 4, enabling multi‑million DKK savings
  • Systematically removed complexity, creating a codebase reliable for a small team to own and extend
  • Changes had a drastic, positive impact on the bottom‑line (cost base and profitability)

ProCollective

Co-Founder & Lead Developer

Copenhagen • March 2020 - July 2022

Co‑founded and led development of a Freelance Management System used by enterprise clients. Our goal was to help companies grow using a flexible workforce.

  • Shipped initial Vue SPA with Rails REST backend
  • Migrated to Rails + Stimulus/Turbolinks, materially increasing delivery velocity
  • Onboarded multiple clients including enterprise clients such as Publicis Groupe while active

Autobutler

Software Developer

Copenhagen • March 2019 - March 2021

Full Stack Ruby on Rails developer on multiple projects.

  • Built algorithms that increased core product revenue
  • Reduced complexity and automated operations; ensured reliable scaling to 1M+ users
  • Delivered major systems including integrations with major insurance companies and a white‑label platform

MIX IT

Co-Founder and Lead Developer

Copenhagen • January 2019 - September 2021

Co-Founded a startup to build a fully functioning mobile ordering and POS (Point of Sale) solution which we named Adea.

  • Built a browser‑based POS in Rails + AngularJS, with heavy focus on real time connections through websockets
  • Launched a mobile ordering app & PWA with the Ionic Framework
  • Landed initial clients; closed after assessing insufficient traction

UNOIT

Lead Software Developer

Copenhagen • February 2016 - February 2019

Led development from zero to production for a platform used by special high schools across Denmark.

  • Adopted by 250+ schools for scheduling, grading, attendance, and more
  • Travelled all over Denmark to host demos for, sell to, and onboard schools
  • Work materially contributed to UNOIT's acquisition by EG

UNOIT

Software Developer

Copenhagen • January 2015 - February 2016

Full‑stack Ruby on Rails and AngularJS developer. Delivered national‑scale systems monitoring the education process of 2M+ Danish citizens, with multiple integrations to Danish government systems.

Notable Experiences

Investments

I've been fortunate to participate in investments through SPVs, in some of the most interesting companies in the world:

Anduril Series B
Groq Series E
Relativity Space Series F
SpaceX $135B valuation
xAI

I've also written multiple smaller checks (< 20.000 USD) for seed-stage companies, where I've invested as part of a syndicate. Most recently in a deep tech company doing satellite propulsion systems.

Advisory & Due Diligence

I've advised technical teams at multiple companies on productivity, building out their foundational architecture. One example is Mindpool (acquired). I've also performed technical due diligence for VCs.

Integrations & Technical Achievements

Selected integrations and scale highlights:

  • Integrations with multiple PSPs (Stripe and Stripe Connect)
  • Large integrations with legacy systems (Nets & Bankgirot for file transfer based payments)
  • Customer.io & Sendgrid (1M+ SMS & emails/month with integrated customer journeys)
  • Background job processing (1 billion+ jobs processed)
  • OAUTH, SAML, Danish Digital ID (NemID) & other SSO
  • Data warehouse enabling analysis across systems for 2M+ citizens

Products & other accomplishments

  • nordiumlabs.com — Software development services agency, specialising in mature Ruby on Rails applications (Founder)
  • førstehelt.dk — Marketplace for first aid course providers (Founder)
  • robinsonlistenapi.dk — Danish‑market API to check marketing protection status (Robinsonlisten)
  • sammenlignkoereskoler.dk — Danish Driving Instructor comparison website (automated data aggregration using AI)
  • akia.io — SaaS that captures and analyzes competitors' emails for market intel
  • WoW & Warcraft communities — Ran large gaming community (100K+ yearly uniques) and contributed to TrinityCore
  • Virtual gold farming — Built an automated operation at age 12, generating meaningful profits

Skills

Programming Languages

Ruby, Python, JavaScript

Frameworks

Ruby on Rails, React, Vue, Angular(JS), React Native, Ionic

APIs & Architecture

GraphQL, REST APIs, Microservices

Databases

PostgreSQL, MySQL, MongoDB

Infrastructure & DevOps

Docker, Heroku, Linux/Nginx, Self-hosted

Frontend & Styling

Tailwind CSS, Bootstrap

Selected Results

  • Autobutler — 2M+ DKK annual tech savings; 11 → 4 team with maintained velocity; drastic bottom‑line impact
  • UNOIT — systems used by 250+ schools; contributed to acquisition by EG
  • Mindpool — advised on product/tech; later acquired
  • VC diligence — technical due diligence across early and growth‑stage deals

Languages

🇩🇰 Danish

Native

🇬🇧 English

Fluent

Contact

[email protected] GitHub LinkedIn

Info

Copenhagen, Denmark

Danish Nationality