O Oskar Karpiński

Skills & Expertise

Languages, frameworks, and tools I use to design, build, and deploy production-grade software — Backend APIs, mobile clients, websites, infrastructure and CI/CD pipelines.

Backend Development

Designing and implementing scalable server-side systems — from RESTful APIs to microservices.

Java/Kotlin

Developing high-performance and scalable backend services using popular frameworks like Spring Boot and Ktor, leveraging Kotlin's modern features for robust applications.

Spring Boot Spring Data JPA Spring Security Hibernate Ktor Coroutines

Go

Building efficient and concurrent backend applications and microservices using Go, focusing on performance, scalability, and robust API development with frameworks like Gin and Fiber.

Gin Fiber GORM Goroutines Channels Context

C#

Creating enterprise-grade web applications and APIs with the .NET ecosystem, utilizing ASP.NET Core and Entity Framework Core for powerful and maintainable solutions.

.NET ASP.NET Entity Framework Core

API Design

Proficient in designing, developing, and documenting various API styles, including RESTful, GraphQL, and gRPC, ensuring secure and well-structured communication between services.

RESTful API GraphQL gRPC JWT OpenAPI

Mobile Development

Building native mobile apps using Jetpack Compose and cross-platform frameworks like Flutter and React Native with high performance and scalability in mind

Jetpack Compose

Building native Android apps using Jetpack Compose and Kotlin Multiplatform for multiple platforms simultaneously

KMP Compose Multiplatform State Management Navigation View Models Dagger Hilt

Flutter

Basic Flutter development skills

Flutter Dart Isolates Material Design

React Native

Basic React Native development skills with Expo

Expo Expo Router NativeWind

Web Development

Developing websites using modern frameworks like React, Next.js, and Astro

React

Building interactive user interfaces with React and its ecosystem

JSX Functional Components Hooks Redux React Query Context API React Router

Next.js

Developing server-rendered and static websites using Next.js with App Router and Pages Router

SSR SSG ISR API Routes App Router Pages Router Data Fetching Vercel

Astro

Crafting fast content-focused websites with Astro for optimal performance and developer experience

Islands Architecture MPA Partial Hydration MDX SSG

Gatsby

Building performant and scalable static sites with Gatsby's GraphQL data layer

GraphQL SSG Plugins Themes

Svelte/SvelteKit

Developing reactive web applications with Svelte's compiler-first approach and SvelteKit

Reactive Programming Stores Actions Server-side Rendering

Styling & UI Frameworks

Proficient in modern CSS frameworks and methodologies for responsive and aesthetic designs

Tailwind CSS Styled-components Sass/SCSS/PostCSS Material UI

Infrastructure & DevOps

Proficient in infrastructure management and DevOps practices, including Docker, Linux, and CI/CD tools

Docker

Containerizing applications for consistent environments and simplified deployment.

Docker Engine Docker Compose Containerization Image Building

Linux Administration

Managing and optimizing Linux-based servers and systems for production environments.

Bash Shell Scripting Ubuntu Debian CentOS Systemd Networking Permissions

CI/CD & Automation

Setting up continuous integration and delivery pipelines for automated testing and deployment.

GitHub Actions GitLab CI/CD Automation Pipelines

Databases

Designing, implementing, and managing various relational and NoSQL databases.

MySQL MariaDB PostgreSQL Redis MongoDB SQL NoSQL Database Design Optimization

Object-Relational Mapping (ORM)

Utilizing ORM libraries to interact with databases in an object-oriented manner.

Hibernate Spring Data JPA GORM Entity Framework Core Prisma TypeORM

Big Data & Analytics

Leveraging data engineering, analysis, and AI-driven insights to extract value from complex datasets and drive informed decision-making.

Python for Data Analysis

Utilizing Python with powerful libraries like Pandas, NumPy and statistical analysis.

Python Pandas NumPy Data Analysis

SQL

Proficient in advanced SQL for complex queries, data aggregation, and managing data in relational databases.

Data Collection & Web Scraping

Developing robust strategies and tools for efficient data acquisition, including web scraping and API integration.

Web Scraping API Integration

AI Agents

Analyzing, visualizing and interpreting data using AI agents and machine learning models.

AI Agents OpenAI APIs

Development Workflow & Tools

Leveraging modern development practices including comprehensive testing, robust version control, efficient IDEs, and AI-powered assistance to build high-quality software.

Testing

Implementing various testing strategies to ensure code quality, reliability, and maintainability across different platforms.

Unit Testing Integration Testing End-to-End Testing JUnit Go Test Jest Vitest

Version Control

Managing source code efficiently with Git and collaborating on projects using popular platforms.

Git GitHub GitLab Branching Strategies Code Reviews

IDEs & Tools

Utilizing powerful Integrated Development Environments and essential tools for efficient coding and debugging.

IntelliJ IDEA Android Studio VS Code Terminal Postman Insomnia

AI Pair Programming

Enhancing productivity and code quality through AI-powered code suggestions, explanations, and assistance.

GitHub Copilot Claude Code OpenCode AI Assisted Development

Interested in working together?

I'm actively seeking internships and junior developer opportunities where I can contribute to meaningful projects, solve real-world problems, and continue growing as an engineer. Let's connect and see how we can build something great together.