Kaj Rusilowski
Web Developer
I build the websites behind Rusilowski Production. Computer Science student in Mannheim, ten years of programming behind me, and professional work across frontend, backend, and DevOps.
How I work
Every site I build starts as code, not as a template. I work with Next.js, React, and TypeScript, style with Tailwind CSS, and generate pages statically so they load fast and stay cheap to host.
The details that decide whether a site actually works get built in from the start: a clean URL structure for every language, canonical tags and sitemaps for search engines, security headers, and contact forms that are rate-limited and protected against spam rather than left open to bots.
What I build with
The tools and practices behind every project.
TypeScript
Next.js, React, and Svelte on the front end; Node.js and Express behind it. Typechecked and linted before every deploy.
Tailwind CSS
Responsive layouts built from scratch, designed to hold up on any screen size.
SEO Foundations
Sitemaps, canonical URLs, hreflang for multilingual sites, and structured data.
Performance
Statically generated pages, optimized images, and as little JavaScript as the job needs.
Backend & DevOps
Python, Go, Java, and C# where they fit, containerized with Docker and running on Kubernetes in Azure, with Git at the center of the workflow.
Contact & Forms
Forms that reach your inbox, with rate limiting, spam traps, and email delivery configured.
Where I have worked
Backend Developer, Working Student
2026 - presentAll For One Group - BlueZone · Heidelberg, Germany
DOM Zone, a document output management solution built on a microservice architecture in Azure, orchestrated with Kubernetes and communicating over Azure Service Bus, with selected Java services rewritten in Node.js to cut resource use.
Data Analysis & Software Development, Working Student
2024 - 2026SAP Deutschland SE & Co. KG · Walldorf, Germany
Python automation for financial reporting and AI agents for large-scale data analysis, plus a calendar component migrated from legacy React to UI5.
Full Stack Developer
2023 - 2024Efebia S.r.l. · Milan, Italy (remote)
Websites and CMS platforms for the ATP Finals, Zipaki, and Tacotoon, built in SvelteKit and TypeScript, with a backend migration from MongoDB to a GraphQL API.
Backend Developer, Internship
2023Utiligence GmbH · Mannheim, Germany
A Smart Meter Gateway simulator with SOAP web services in an SAP system, written in ABAP with a React front end.
Selected work
Platforms I built or helped build before this one.
ATP Finals 2023 & 2024
Tournament platform with two CMS admin panels and a mobile app, including NFT redemption for participants.
Tacotoon
Webtoon-style web app for publishing and reading user-generated comics. Led the frontend, contributed backend, CI/CD, and AWS deployment.
Zipaki
Comic catalog platform with backend services on Fastify and a Neo4j graph database, plus a local search engine for instant results.
CodeDuel
Competitive programming platform running submitted code in isolated Docker containers. Go and C# microservices with a SvelteKit front end.
Have a project in mind?
Tell me what you need and I will tell you what it takes to build it.