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Krzysztof Gąsiewski

Krzysztof Gąsiewski

Full-stack & systems engineer

Student developer from Warsaw who builds full-stack apps and cares most about what keeps them safe: authentication, secure code and hardened Linux servers.

  • Open to work & collaboration
  • Warsaw, Poland
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About me

I'm Krzysztof - a 16-year-old developer from Warsaw, currently in my second year at Techni Schools, where I'm training to become a programming technician.

I build full-stack applications, but what really pulls me in is what happens underneath. I'm into cybersecurity and authentication systems, and I care about writing code that's secure by design - software that keeps the wrong people out without getting in the way of the right ones.

Outside the editor I set up and harden Linux servers, configure databases and web servers, and run multi-node Pterodactyl Panel deployments. I'm always learning something new, whether it's a language, a tool or a better way to lock things down.

profile.js
const krzysztof = {
  location: "Warsaw, Poland",
  school: "Techni Schools",
  role: "student developer",
  focus: ["security", "auth", "infra"],
  stack: ["Node.js", "Python", "SQL"],
  speaks: ["Polish", "English"],
  openToWork: true,
};

Skills

What I work with and what I focus on.

Linux hardening

Locking down servers with SSH hardening, firewalls, least privilege and sensible defaults.

Authentication systems

Designing login flows, sessions and token-based auth that hold up against real-world attacks.

Server infrastructure

Setting up web servers, databases and multi-node Pterodactyl Panel deployments from scratch.

Full-stack development

Building APIs with Express, FastAPI and Sanic, and interfaces with React and Next.js.

Programming languages

  • JavaScript Node.js
  • Python
  • SQL
  • C# junior
  • C++ basic

Frameworks & libraries

  • React
  • Next.js
  • Express
  • FastAPI
  • Flask
  • Sanic

Databases

  • PostgreSQL
  • MySQL
  • MariaDB
  • MongoDB
  • Redis

Infrastructure

  • Linux Debian / Ubuntu
  • Nginx
  • Docker
  • systemd
  • Pterodactyl Panel multi-node

Security

  • Server hardening
  • SSH hardening
  • Firewalls (UFW, iptables)
  • Fail2ban
  • JWT & sessions
  • Password hashing (Argon2, bcrypt)

Tools

  • Git
  • GitHub
  • DBeaver
  • VS Code
  • Postman

Spoken languages

  • Polish native
  • English advanced

Projects

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    Education

    Where I'm learning now, and where it all started.

    1. 2025 - present Current

      Niepubliczne Technikum Programistyczne Techni Schools w Warszawie

      Programming technician · 2nd year

      Five-year technical school focused on software development - web applications, databases, desktop and mobile programming - preparing for the INF.03 and INF.04 professional qualifications.

    2. Before technical school Multiple awards

      Giganci Programowania

      Programming courses

      Where it all started - a series of programming courses that built my foundations and earned me multiple awards along the way.

    Let's build something secure.

    Have a project, an idea or an opportunity? I'm open to work and collaboration - drop me a message.

    GitHub

    Command palette