Hi, I'm Maciej Serafin

Backend-oriented application designed to automatically fetch, process, and store foreign exchange rates from the official National Bank of Poland (NBP) API. The system is built as a modular, multi-module Java application with clear separation of responsibilities between core business logic, external API integration, persistence layer, and application runtime. Exchange rates are periodically updated, validated against duplicates, stored as historical data, and exposed via a REST API for further consumption.

• Java
• Spring Boot
• Multi-module Maven
• REST API
• PostgreSQL
• JPA / Hibernate
• Docker
• Scheduler
• Caching (Caffeine)
• Clean Architecture

A library management backend built with Spring Boot, designed around REST endpoints for books, users, libraries, and borrow operations. The project uses a layered structure with controllers, services, repositories, DTOs, exception handling, and database persistence, together with filtering and borrow/return flows for core library operations.

• Java 21
• Spring Boot
• REST API
• Spring Data JPA
• PostgreSQL
• OpenAPI

A simple desktop task manager built in Java Swing to practice creating GUI applications, handling user input, and organizing application logic around a dedicated task model and manager class. The app allows adding tasks with a name, description, and priority, displaying them in a list, and removing selected items from the interface.

• Java 17
• Java Swing
• Maven
• Desktop GUI
• Builder Pattern
• In-Memory Task List

A larger top-down 2D game project built in Java with a custom game loop, tile-based world, NPC interaction, collectible items, and both ranged and melee combat modes. The project also includes audio, map resources, collision handling, bullets, and a separate map editor, making it a broader exercise in gameplay systems and game architecture.

• Java
• Java Swing
• 2D Tile Engine
• Game Loop
• Combat System
• Map Editor

Java-based narrative engine for running text visual novels as external story modules. The runtime is built around a hierarchical content structure (Story -> Day -> Section -> Scene -> Block) and supports Narrative, Dialogue, Monologue, Choice, and Action blocks. Stories are discovered from a dedicated directory, compiled at runtime, loaded dynamically, and started from a selected scene. The engine includes branching options, scene jumps, structured navigation targets, a custom Swing reader window with typewriter-style rendering, toolbar-based controls, and a state-driven flow covering menu, gameplay, settings, and creator screens.

• Java
• Swing UI
• Gradle
• Engine Architecture
• State Management
• Hierarchical Story Model
• External Story Loading
• Runtime Compilation
• Branching Logic
• Custom Runtime Design

A desktop implementation of Flappy Bird built in Java Swing with a custom game loop, keyboard controls, collision detection, scoring system, and restart flow. The project also includes background music and sound effects, making it a practical exercise in combining gameplay logic, rendering, and audio handling in a simple 2D Java game.

• Java 22
• Java Swing
• Game Loop
• Collision Detection
• Keyboard Input
• Audio Effects

Backend-focused web application for task management built in pure PHP without frameworks. The project was created to understand full request-response flow, session handling, access control, and data persistence. Application logic is separated into dedicated classes, with manual routing, role-based access (admin defined by configuration), and CSV-based storage with automatic backup mechanism.

• PHP
• HTML
• CSS
• Session Auth
• CSV Storage

Backend-oriented web application for managing a simple book library, built in pure PHP. The project focuses on understanding basic application architecture, object-oriented programming, form handling, and data persistence. Domain logic is separated into classes and utility functions, with CSV used as a lightweight storage layer.

• PHP
• HTML
• CSS
• CSV Storage
• Object-Oriented Programming (Book model)
• Form handling (add / delete)