I'm Patrik, a full-stack developer from Košice, Slovakia.

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What else I build and do

Besides the services above, I build other custom systems and take care of the work around them. You'll find more detail under custom software development:

• Mobile apps, for example for the warehouse or for work in the field
• UI/UX design and clickable prototypes
• An AI chatbot for your website that answers customers
• Cloud and DevOps: deployment, Docker, CI/CD, Google Cloud and Vercel
• AI training: 4 hours from €600

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Why I enjoy websites and UX

I got hooked on websites at secondary technical school, about ten years ago. I built them in my free time too and always tried to do a bit more than I had to, just to learn as much as I could. The hobby turned into a job, but that approach has stayed with me.

At the Technical University of Košice, both my bachelor's and master's theses focused on UI and UX. In my master's thesis I also took on AI: the topic was a personalized AI assistant, but I cared just as much about making it pleasant for people to work with. Later I taught UI/UX design at Stredná odborná škola informačných technológií, a vocational IT secondary school in Košice.

That's why, with every system I build, I care not only about whether it works but also whether people can find their way around it without a manual. I approach websites the same way: in a website redesign, I make sure the site loads fast, can be used with just a keyboard and can be found by both Google and ChatGPT. My own site scores 100 for both accessibility and SEO in Lighthouse's mobile test.

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How we work together

The consultation is free, and so is the prototype: I build it once you accept the quote or some of its parts, so you only make your final decision after you've tried it.

Projects start at around €500: that's what a single automation, an integration or a smaller tool costs, a few days of work. A system your company runs on every day, such as a CRM, is a project lasting several months, and I split the quote into parts so you can start with the one that helps you most. Running costs (hosting and AI) range from tens of euros to the low hundreds a month. A 4-hour AI training session starts at €600. The price depends on complexity and scope, and the timeline mainly on how many of your systems need to be connected. You'll get a specific price and timeline after our first call. I'm not a VAT payer, so I don't add VAT to my prices.

• Consultation: 30 to 60 minutes, online, in person or by phone. We go through where your company loses the most time, and you find out whether anything is worth building.
• Quote: after the consultation, you get a quote split into parts, each with a specific price and delivery date.
• Prototype: if you accept the quote or any part of it, I build a prototype on a sample of your data, free of charge and with no obligation.
• Order: after the prototype, you make your final decision. You pay 20% when you order and the rest after handover.
• Delivery: full deployment usually takes 6 to 12 weeks and includes documentation and training for the people who will work with the system.
• Hosting and operation: by default, I run the system on my own accounts (Vercel, Supabase) for a monthly fee. Moving it to your own accounts can be arranged.
• Bugs and changes: I always fix bugs for free in any system I've built, because I'm responsible for it. New features and changes beyond what we agreed are priced separately.
• Personal data: if I have access to personal data the system processes, for example because it runs on my accounts, we sign a data processing agreement under Article 28 of the GDPR. In it, I act as the processor and also list the sub-processors the system uses, such as the hosting, database and language model providers.
• Capacity: I take on two new clients a month and reply to messages within eight hours.

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Work experience

I worked at U.S. Steel Košice and GymBeam, taught at a vocational secondary school, and since 2026 I've been a development partner to the AI agency Eturial. Since October 2026 I've been working full-time on my own business and I'm taking on new clients.

From 2022 to 2026, I worked part-time at U.S. Steel Košice as the only developer in my department. I designed and built web portals and internal tools from requirements through to deployment, and then maintained them. I integrated systems across departments, managed databases and worked on projects deployed on Kubernetes.

In 2026 I worked full-time at GymBeam as a full-stack developer on the Boxpi project team. I was an employee there and never worked for them as a freelancer, which is why I don't describe the project in detail in public. I'll just mention that I built an AI agent for invoicing there.

From 2025 to 2026, I taught web development, UI/UX design and the Internet of Things (IoT) at Stredná odborná škola informačných technológií, a vocational IT secondary school in Košice, using my own teaching materials. I also draw on that experience when I run AI training for teams.

For clients of the AI agency Eturial, I build custom solutions and take them all the way into production. Through Eturial, I wrote the security layer for the CRM and client portal of DAU, a Slovak tax and accounting firm. The system runs on Next.js, Supabase and PostgreSQL, and the security layer consists of Row Level Security policies that decide, inside the database, who can see and change which records. I also rebuilt the client portal and the dashboard.

I also work for my own clients. For Účtovný dom, an accounting firm in Košice, I built a tool that automates its invoicing on top of POHODA. Now I'm building client dashboards for the firm, where its clients will see figures from their own books.

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Education and awards

I hold a master's degree (Ing.) in informatics from the Technical University of Košice. Counting secondary technical school, I spent almost ten years studying IT.

• Technical University of Košice (TUKE), Faculty of Electrical Engineering and Informatics: bachelor's (Bc.) and master's (Ing.) degrees in informatics, 2021 to 2026
• Stredná priemyselná škola elektrotechnická (secondary technical school of electrical engineering), Komenského 44, Košice: 2017 to 2021
• Živé IT projekty 2025, a student project competition run by the Department of Computers and Informatics at FEI TUKE and Košice IT Valley: team lead, 2nd place out of 64 teams

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Technologies I work with

I mostly write TypeScript: I build user interfaces in React and Next.js and the back end in Node.js, and I store data in PostgreSQL or MySQL. I also choose tools based on what your company already uses.

• Frontend (React, Next.js, TypeScript, Tailwind CSS, TanStack Query, Vue.js, UI/UX design): the screens and forms people work in every day
• Backend (Node.js, REST APIs, Python, PHP): business logic and API integrations
• Data (PostgreSQL, MySQL, Supabase, Prisma): databases and access permissions
• Cloud and DevOps (Google Cloud, Cloud Run, Terraform, Docker, Kubernetes, GitLab CI, Vercel, Git): deployment, scheduled jobs and infrastructure as code
• AI (LLM APIs, Vercel AI SDK, AI agents, Claude Code): reading documents and emails, agents that follow fixed rules, and AI-assisted development
• Testing (Vitest, Playwright): automated tests that check everything still works after a change

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Contact and profiles

The quickest way to reach me is by email or through the form at the bottom of this page, where you can also book a 30-minute call on Google Meet.

• Email: patrik.krajnak.dev@gmail.com
• Phone: +421 950 625 466
• LinkedIn: Patrik Krajňák
• Languages: Slovak (native), English (B2), German (A2)