Karol Has

Fullstack Developer

I craft digital experiences by building modern, performant, and beautiful web applications using cutting-edge technologies.

About Me

Below, you can explore my professional journey, my commitment to continuous self-growth, and the hobbies that have shaped my discipline and mindset.

For the past 4 years, I have been obsessively teaching myself the art of software development. As a self-taught developer, I've built a foundation of resilience and proactive problem-solving skills that allow me to master new technologies quickly and independently.

What I bring to the table:

  • Military-grade reliability: Bringing extreme attention to detail, a methodical approach to documentation, and a deep respect for data integrity and system procedures
  • Resourceful learner: Proven ability to quickly pick up new tools and frameworks through documentation and research, translating new knowledge into working features
  • Independent Project Management: Proven ability to take a project from concept to a live environment, ensuring all pieces—frontend, backend, and data—work together seamlessly

My transition into professional development was driven by freelancing and community-focused projects. Beyond just writing code, I’ve built and maintained platforms used by hundreds of active users every month, bridging the gap between technical execution and real-world utility.

2022 - present

Freelancer

Reliability, architecture, scalability

  • Architected scalable frontend solutions with React and Next.js, emphasizing component reusability and high-performance rendering
  • Streamlined data fetching and server-state management using TanStack Query and Axios to ensure efficient API interaction and data caching
  • Boosted conversion and organic traffic by optimizing Core Web Vitals and implementing advanced SEO strategies
2023 - present

Military Service

Leadership, discipline, responsibility

  • Managing sensitive data workflows with rigorous attention to detail, ensuring 100% compliance and information security
  • Demonstrated exceptional time management by balancing high-responsibility military duties with consistent fullstack project delivery
  • Cultivated a proactive problem-solving mindset and resilience, thriving in high-pressure environments that demand reliability and precision
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Featured Projects

A selection of my recent work

🛡️

Idle Clans Hub

A high-performance Next.js analytics platform for MMORPG players featuring profit calculators and real-time data visualization, serving hundreds of active monthly users.

ReactNext.jsTypeScriptTailwindSEO
View Project →
🤸‍♂️

Skorygowani

A professional full-stack platform built with Angular and .NET Core, featuring secure user scheduling modules and robust data integrity protocols.

Angular.NET CoreTypeScriptMongoDBREST APITailwind
View Project →
💎

Mana Clicker

An interactive browser-based incremental game developed with React and Zustand to demonstrate complex global state management and custom game loop logic.

ReactZustandTypeScriptTailwindAxiosClerk (Auth)
View Project →

Skills & Technologies

Tools I work with daily

Frontend

  • React & Next.js
  • Typescript
  • Angular
  • CSS, Tailwind CSS, Module CSS
  • State Management (Zustand, Redux Tanstack Query)

Backend & Databases

  • Node.js & Express
  • Nest.js
  • MongoDB & PostgreSQL
  • RESTful APIs & Axios

Tools

  • Git & GitHub
  • Docker
  • Jest & Testing Libraries
  • CI/CD Pipelines
  • AI (Claude, GPT-5, etc.)

Performance

  • Lighthouse Optimization
  • Core Web Vitals
  • Advanced Caching
  • Responsive Web Design
  • SEO Strategy

Let's Work Together

I'm currently available for freelance projects and full-time opportunities. Let's create something amazing together.

karolhas.kontakt@gmail.com