Marcus Wilstrup
Crew fileEngineer, tech lead and investor. Open to hard problems, any stack.
Engineer and tech lead.
Ten years of Rails and a few companies of my own.
Engineer. I lead engineering for other teams, build my own products and invest in a few companies. Tech lead at Autobutler, some short development contracts, technical due diligence for VCs now and then, and my own products.
Before that I was tech lead at Autobutler, co-founded two companies, and worked on national systems covering the education of 2M+ Danish citizens at UNOIT.
- Now
- Tech Lead / Software Developer, freelance
- Languages
- Danish (native), English (fluent)
- Online
- marcuswilstrup.com
Experience
Ten years, most recent first– presentFreelance
Freelancer
Tech Lead / Software Developer
Tech lead at Autobutler, some short development contracts, technical due diligence for VCs now and then, and my own products.
- Tech lead at Autobutler
- Technical due diligence for VCs
- Building and running my own products, like Tabularium and Notarium
– Employed
Autobutler
Tech Lead / Software Developer
Led a small team on a big codebase: a Rails monolith, a few Ruby and Elixir services, and a React app.
- Cut tech spend by 2M+ DKK a year in infrastructure alone
- Went from 11 engineers to 4 without slowing delivery
- Removed complexity so a small team could own the codebase
- Brought the cost base down
– Founder
ProCollective
Co-Founder & Lead Developer
Co-founded a system for companies to manage their freelancers, and led development. We shut it down in 2022.
- First version was a Vue app on a Rails backend
- Moved to Rails with Stimulus and Turbolinks, which made us faster
- Clients included Publicis Groupe
– Employed
Autobutler
Software Developer
Full-stack Rails developer across multiple projects.
- Built algorithms that raised revenue on the core product
- Simplified and automated operations as the platform grew to 1M+ users
- Built integrations with large insurance companies and a white-label platform
– Founder
MIX IT
Co-Founder & Lead Developer
Co-founded a startup building Adea, a mobile ordering and point-of-sale system.
- Built a browser-based point of sale in Rails and AngularJS, with websockets
- Built a mobile ordering app with Ionic
- Got our first clients. Closed in 2021
– Employed
UNOIT
Lead Software Developer
Led the build of a platform for special high schools across Denmark, from nothing to production.
- Used by 250+ schools for scheduling, grading and attendance
- Drove around Denmark to demo it to schools and get them started
- UNOIT was later acquired by EG
– Employed
UNOIT
Software Developer
Rails and AngularJS developer on national systems following the education of 2M+ Danish citizens.
- Worked on national education systems
- Built multiple integrations with Danish government systems
Skills
- 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
- Tailwind CSS · Bootstrap
Languages
- DanishNative
- EnglishFluent
Advisory & diligence
Advised engineering teams, including Mindpool (acquired). Technical due diligence for VCs.
Integrations & scale
Stripe and Stripe Connect, Nets and Bankgirot file-based payments, Customer.io and SendGrid at 1M+ SMS and emails a month, 1B+ background jobs processed, OAuth, SAML and NemID single sign-on, and a data warehouse covering 2M+ citizens.
Investments
Growth stage
- SpaceX (SPV, 2023 · now public)
- Relativity Space (SPV, 2024)
- xAI (2025 · merged into SpaceX, 2026)
- Anduril (Series G & H, 2025–26)
- Groq (Series E, 2025 · exited 2025)
- Erebor (2026)
Early stage, via syndicate
- Hosted AI (Seed, 2023)
- Braive (Seed, 2023)
- North Propulsion (Seed, 2024)
Names and stage only; public holdings.
Classifieds
Reply by any channel below.- Wanted: something hard to build, or something slow and expensive to make fast and cheap. Any stack. Write to marcuswilstrup@gmail.com.
- Fractional CTO & tech leadership: Companies whose tech has become more complicated and more expensive than it should be. I lead the engineering team a few days a week and simplify what is there.
- Rails for mature applications: Teams with a Rails app that has been in production for years. I work through the codebase and ship, without a big rewrite. Through Nordium Labs.
- Technical due diligence: VCs, angel investors and acquiring companies. A written read of the team, the architecture and the technical risk.
- Contact:
Always current: the live edition of this file is at marcuswilstrup.com/cv.