Skills | Gerwin Kuijntjes

I’m a backend and infrastructure engineer with an entrepreneurial mindset. Most of my actual work is in .NET (C#) for backend, React or Astro for frontend, and Kubernetes with OpenTofu for infrastructure. I think in systems: both the technical architecture and how people will actually use it.

I’ve worked across enough different stacks to know that the hard parts don’t really change. The fundamentals of API design, distributed systems, database performance, infrastructure cost: those don’t depend much on which language or framework you’re using. That’s why I can pick up something unfamiliar relatively quickly: I already know what I’m looking for and what questions to ask. The tool is the last thing to learn.

Outside my day job, I co-founded StaticForm, a form-backend SaaS I built from scratch and took all the way to production. Real users, real infrastructure, every part of the stack owned and maintained. Building something end-to-end yourself (product, backend, frontend, infrastructure, monitoring) is a different kind of exercise than working on an existing codebase, and it shows in how I think about problems.

My strongest areas are infrastructure and backend: designing production-grade Kubernetes setups, writing infrastructure as code, cutting cloud costs, and building APIs that actually hold up under real usage. A concrete example of what that looks like in practice: at my current job I migrated the entire hosting stack from Azure App Services to a self-hosted K3S cluster, saving over €1,400 a month. I also convert server-side websites to static sites when possible. Simple, secure, fast.

Non-Technical Skills

Stakeholder communication: Primary point of contact for stakeholders: handling support questions and gathering requirements through intake conversations.

Technical writing: Writing documentation, architecture overviews, and decision documents that are accessible to non-technical readers as well.

Cost analysis: Making infrastructure costs transparent and building a business case for migrations or architecture changes.

Product ownership: Taking a product from idea to production, including prioritization, scope definition, and delivery.

Technical Capabilities

Backend: Building APIs and backend services in .NET (C# / ASP.NET Core). REST APIs, authentication, database design, error handling. This is where most of my actual work time goes.

Infrastructure and DevOps: Setting up Kubernetes clusters, writing OpenTofu infrastructure as code, GitOps with ArgoCD, managing cloud costs. I prefer owning the infrastructure rather than renting managed services.

Frontend: Building SPAs with React (Vite) for SaaS products, and static sites with Astro for content-heavy websites. I’m not primarily a frontend engineer, but I can build complete products.

Database: PostgreSQL for most things. Query optimization, indexing, schema design.

AI & LLM: LLM integrations in production projects (classification, summarization, validation). working daily with AI-assisted and agentic coding workflows, applying current best practices around prompt design, context management, and cost control. Experience with Anthropic Claude and OpenAI.

Full Stack: I can take a product from idea to deployed infrastructure. StaticForm is a concrete example: a form-backend SaaS I co-built and co-own, with real paying users, submission queuing with retries, load balancing, spam filtering, full observability with action logging and failure alerts, multi-channel notifications, and a complete admin and subscriber interface. Slicekit is a production-grade .NET + React SaaS template I built and sell under a commercial license.