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My Expertise

Crafting robust solutions with Java & modern web technologies

Backend Development

Java Ecosystem

Building scalable backend systems using Java and Spring ecosystem. Experience with REST APIs, database integration, cloud services, and event-driven architecture.

Java Spring Boot Spring Security REST API MySQL AWS EC2/S3 Kafka Maven Hibernate JUnit Mockito

Frontend Development

Modern Web Technologies

Building responsive and dynamic user interfaces and integrating them with backend services using modern web technologies.

JavaScript TypeScript Svelte HTML CSS3 Thymeleaf Bootstrap Java FX

Architecture, Tools & Practices

Clean Code & Software Design

Applying software design principles, clean architecture practices, and modern development tools to build maintainable and scalable applications.

DDD DTO Pattern AI Coding Tools GitHub Swagger OOP & SOLID Design Patterns Dependency Injection Exception Handling

My Projects

TIME BOOKING &
SCHEDULING

Full-Stack Appointment Booking Application

BookingPlatform
View Live Project
BookingPlatform
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BookingPlatform is a full-stack appointment booking application that enables organizations to manage services, specialists, and client bookings with real-time availability checking, built using Domain-Driven Design and a modern reactive frontend.

The system is divided into two main components: a REST API and a Client Web Application - both seamlessly integrated to deliver a dynamic and engaging experience.

Backend (Spring Boot REST API)

  • Domain-Driven Design (DDD) architecture with 5 bounded contexts: Booking, Organization, Schedule, Service, and Shared
  • Spring Security with OAuth2 Resource Server and JWT-based authentication and role-based authorization
  • Apache Kafka for event-driven messaging - publishes booking events and triggers email notifications asynchronously
  • Spring Mail integration with Gmail SMTP for automated booking email notifications
  • Swagger / OpenAPI documentation for comprehensive API exploration
  • MySQL database integration using Spring Data JPA repositories with Hibernate ORM
  • Strict layered architecture per bounded context: API → Application → Domain → Infrastructure
  • Value Objects for domain integrity - TimeSlot, ServiceDuration, booking state machine (PENDING → CONFIRMED → CANCELLED)
  • Testcontainers with MySQL 8.0 for integration tests running against a real database in Docker
  • Global Exception Handler providing centralized, consistent error management across all endpoints

Frontend (SvelteKit SPA)

  • SvelteKit with Svelte 5 for a fast, reactive single-page application
  • TypeScript for type-safe frontend development
  • Tailwind CSS 4 utility-first styling with custom brand color scheme
  • Flowbite-Svelte component library for polished, consistent UI elements
  • Lucide-Svelte icon set for clean, modern iconography
  • Role-based routing - separate dashboards for Clients, Specialists, Org Admins, and Global Admins
  • JWT auth store with localStorage persistence, auto-logout on 401, and derived role-based state

Source Code

BookingPlatform
swagger-logo
Swagger documentation

"Only in the darkness can you see the stars." — Martin Luther King Jr.

COSMO TRAIL

Cosmo Trail — Explore, Build, and Conquer the Universe 💫

Cosmo Trail
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Cosmo Trail
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🚀Cosmo Trail is a full-stack space exploration simulation application that combines strategic crew management with dynamic mission outcomes, built using modern Java enterprise technologies and a clean microservices architecture.

The system is divided into two main components: a REST API and a Client Web Application — both seamlessly integrated to deliver a dynamic and engaging experience.

⚙️ Backend (Spring Boot REST API)

  • Spring Security implementation with role-based authentication and authorization
  • Swagger documentation for comprehensive API exploration
  • EC2 deployment showcasing cloud infrastructure management skills
  • AWS S3 integration for scalable image storage and retrieval
  • MySQL database integration using Spring Data JPA repositories for efficient data persistence
  • DTO pattern with ModelMapper for clean separation between database entities and API responses
  • Global Exception Handler providing centralized, consistent error management across all endpoints
  • Apache PDF generator for dynamic mission report exports

🎨 Frontend (Spring MVC Client)

  • Thymeleaf templating engine for server-side rendering
  • Bootstrap framework for responsive, modern UI design
  • Custom JavaScript for enhanced interactivity
  • Three.js for creating an interactive 3D space map with space destinations
  • Spring Security integration maintaining authentication across the application
  • Service layer architecture mirroring backend patterns for maintainable code
  • Global Exception Handler ensuring graceful error presentation to users

📂 Source Code

Backend Repository
Space Exploration Server
Frontend Repository
Space Exploration Client
swagger-logo
Swagger documentation

Peony Bloom

Peony Bloom - E-Commerce Flower Shop

Cosmo Trail
View Live Project
Peony Bloom
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Peony Bloom is a full-featured e-commerce application for a flower shop, built with Spring Boot and an interactive JavaScript-powered frontend. It offers an intuitive catalog with smart filters, secure user authentication for purchases, and an admin dashboard for product management and sales tracking.

⚙️Integrated Backend & Frontend

  • Spring Security with role-based access control distinguishing between customers and administrators
  • Service layer architecture maintaining separation of concerns and business logic encapsulation
  • EC2 deployment showcasing cloud infrastructure management skills
  • MySQL database with Spring Data JPA and CRUD repositories for efficient data management
  • DTO pattern ensuring clean separation between persistence and presentation layers
  • Thymeleaf server-side templating integrated with Spring MVC controllers
  • Bootstrap framework for responsive, professional UI design
  • Custom JavaScript for dynamic, client-side interactivity

📂 Source Code

Peony Bloom - E-Commerce Flower Shop

NetFlow Manager

Internet Package Manager - JavaFX Desktop Application

Internet Package Manager - Screenshot 1
Internet Package Manager - Screenshot 2
Internet Package Manager - Screenshot 3
Internet Package Manager - Screenshot 4
Internet Package Manager is a modern JavaFX and Spring Boot desktop application for managing internet subscription packages. It features CRUD operations for customer data, advanced filtering, and real-time statistics. Built with strong form validation and an efficient double-click editing workflow, it ensures accurate data handling and streamlined customer service management.

⚙️Backend Integration & JavaFX Frontend

  • Spring Boot with JavaFX integration using custom StageReadyEvent for lifecycle management
  • FXML-based UI with custom CSS styling for modern, professional appearance
  • JPA repositories for database operations
  • MySQL database integration with entity-relationship mapping
  • Jakarta Validation with custom validators for comprehensive input validation
  • Custom exception handling with PackageServiceException for robust error management
  • Transactional service layer ensuring data consistency and integrity
  • SLF4J logging throughout the service layer for debugging and monitoring
  • Mapper pattern separating domain entities from UI models for clean architecture

📂 Source Code

Internet Package Manager

Random facts about me


I'm highly motivated and always eager to learn, with a strong focus on exploring new technologies and best practices to improve code quality.
I'm also a kind person, a passionate tea lover, and I definitely debug code better with a warm cup in my hands!☕


CONTACT

Get in touch with me via social media or email me.

GitHub
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CV
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WhatsApp
+40 756 435 953
Gmail
ecaterinabjr@gmail.com
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