← Aaron Metzelaar

Software Engineer

Aaron Metzelaar

I'm a software engineer who likes building things that feel simple on the outside and solid underneath. My work combines product thinking, frontend engineering, automation, and AI tooling, with a focus on turning unclear ideas into practical solutions people actually enjoy using. I'm curious, hands-on, and collaborative, and I enjoy helping teams work smarter as much as I enjoy building the product itself. Off the clock, I play football, organise events with friends, and I'm always up for a good specialty coffee.

aaronmetzelaar@gmail.comgithub.com/AaronMetzelaarNetherlands · Dutch (native) · English (fluent)

Experience

MatchWornShirt · Frontend Engineer

2023 – Present

Work across the public marketplace, mobile app, and internal admin tools as a T‑shaped engineer: frontend and product at the core, reaching across the stack into server-side Node, Python, and C#, SQL, and Docker, AWS, and CI/CD for delivery. AI-assisted tooling runs through all of it.

Frontend & product engineering

  • Built and maintained customer-facing and internal features across web, mobile app, and admin tooling
  • Designed interactive and spatial interfaces using real-time input, visual feedback, and reusable patterns to create intuitive user experiences
  • Improved frontend maintainability through shared composables, reusable implementation patterns, refactoring, and documentation
  • Designed product-critical workflows across CMS-driven content, operational tooling, translation flows, and cross-platform frontend logic
  • Delivered solutions through cross-functional collaboration with product, design, marketing, support, and engineering
SkillsVueNuxtReact NativeTypeScriptJavaScriptHTMLCSSTailwindWebGL / Three.jsInteractive spatial interfacesReal-time interactionComponent architectureDesign systemsCross-platform frontend

AI tooling & developer productivity

  • Designed and maintained the internal AI agent ecosystem for frontend and mobile engineering
  • Built MCP servers, agent skills, and reusable workflows for codebase context, specialist code review, documentation, worktrees, and engineering automation
  • Standardised team-wide AI adoption through shared tooling, guidance, and quality controls
  • Increased AI co-authored PR adoption from 5% to 35% in four months
SkillsAI agentsAgentic workflowsMCP serversAgent skillsLLM toolingPrompt and context designWorkflow automationDeveloper experienceAI enablement

Localisation & content infrastructure

  • Revived a deadlocked translation project and turned it into a scalable multilingual publishing system
  • Replaced a blocked backend-first approach with a practical localisation strategy across CMS content, UI copy, validation, and release workflows
  • Reduced manual translation overhead and release risk with cleaner content structures, automated checks, and developer-friendly workflows
  • Enabled reliable publishing across 12 languages for multiple products
SkillsArchitecture & solution designCMS integrationsInternationalisationAutomationCI/CDStoryblokCrowdin

Payments, checkout & business impact

  • Introduced Klarna across web and app, establishing reusable payment logic for company products
  • Improved checkout visibility and consistency, reducing unpaid orders by 40%
  • Validated placement decisions through A/B testing, ad hoc analysis, and product research, prioritising high-impact implementation over unnecessary scope
SkillsPayment integrationsCheckout optimisationKlarnaConversion-focused UXA/B testingData-informed decisions

Engineering quality & team enablement

  • Top reviewer and contributor across web, app, and admin codebases
  • Improved developer experience by standardising workflows, AI workflow guidance, documentation, and reusable engineering practices
  • Coached engineers through presentations and hands-on sessions on AI-assisted development, code quality, workflow adoption, and responsible tool usage
SkillsCode reviewsDeveloper experienceTechnical coachingAI-assisted engineeringKnowledge transferTechnical communication

Highlighted projects

  • Internal AI agent ecosystem: Increased AI co-authored PR adoption from 5% to 35% by turning individual experimentation into structured team workflows
  • Translation & localisation workflow: Revived a stalled translation project and scaled multilingual publishing across 12 languages, 154,500+ CMS words, and 11,500+ strings
  • Interactive frontend architecture: Designed reusable spatial and 360° interaction patterns, contributing to 60% higher user engagement
  • Mixed Reality framework: Built a modular Unity framework combining computer vision, physical-object tracking, and responsive projected interfaces

Education

BSc Computer Science

University of Amsterdam · 2024

Thesis: Projection-Based Interaction using Tangible Objects. A modular Mixed Reality framework built in Unity (C#): real-time computer-vision tracking of physical objects through a camera and projector pipeline, with calibration and projection mapping that connect them to responsive spatial interfaces.

DomainsComputer VisionSoftware ArchitectureGame Engine DevMixed/Extended RealityReal-time Interactive SystemsHCI
github.com/AaronMetzelaar/MRFrameworkThesis (PDF)