Hire the Best Eclipse Developers & Programmers
in Ukraine

Need a web application, REST API, mobile app, bug fix, or reliable software testing? I can help you turn the task into a working, tested, and documented solution. I am a full-stack software developer with practical experience in backend, frontend, mobile development, API integration, databases, automated testing, and application troubleshooting. My main areas of work: • Web application development with React and TypeScript • Backend development with Java and Spring Boot • REST API development, integration, and documentation • MySQL database design and application integration • Mobile development with Flutter, Dart, Kotlin, and Jetpack Compose • Firebase Authentication and Cloud Firestore integration • Manual and automated software testing • API testing with Postman, Swagger, JUnit, and RestAssured • Bug investigation, reproduction, fixing, and verification • Docker-based local environments and application setup • Technical documentation and project configuration Selected projects: Book Exchange — a full-stack platform built with Java, Spring Boot, React, TypeScript, MySQL, Docker, and REST APIs. It includes authentication, role-based access, book ownership workflows, an administrator panel, database migrations, OpenAPI documentation, 77 backend tests, and 30 independent API tests. CarNation — a Flutter and Firebase vehicle marketplace with authentication, vehicle search and comparison, saved items, Firestore request management, real-time status updates, security rules, and 64 automated tests. Kvantor — an Android learning application built with Kotlin, Jetpack Compose, Firebase, Firestore, progress tracking, gamification, and an AI-assisted learning feature. I can work on both small and larger tasks, including fixing one API endpoint, connecting a frontend to a backend, adding a new feature, testing an existing application, improving database logic, configuring a project locally, or developing a complete application module. What you can expect: • Clear and regular communication • Honest estimates and progress updates • Clean, understandable, and maintainable code • Careful testing before delivery • Documentation and setup instructions • Attention to requirements and edge cases Technologies: Java, Spring Boot, Spring Security, Spring Data JPA, Hibernate, REST APIs, MySQL, React, TypeScript, Flutter, Dart, Kotlin, Jetpack Compose, Firebase, Docker, Maven, Git, GitHub, JUnit, RestAssured, Postman, Swagger, and OpenAPI. I am ready to help with web development, backend services, mobile applications, API integrations, testing, bug fixing, and technical support.

👋 Need a high-load Java platform that scales without a glitch? 🚀 I provide full-stack ownership with Spring Boot and React Native, turning complex ideas into secure, production-ready reality. Backed by 20+ years and 100+ delivered projects, I build code that works for your bottom line, not just your repo. Check out my page to see my portfolio! 🛡️ As a Java Developer I've built high-load backend systems, REST AP payment solutions document processing platforms, and business applications used by thousands of users. As a Full Stack Developer and React Native Developer I've helped startups and growing companies launch scalable products while maintaining security, performance, and compliance. Throughout my career, I've worked with startups, established businesses, and enterprise clients, helping them transform ideas into reliable software products. My experience covers the entire development lifecycle, from architecture planning and technical discovery to development, deployment, optimization, and long-term support. My expertise includes Java Developer Spring Boot React Native AWS PostgreSQL Docker Kubernetes microservices cloud infrastructure and secure software architecture 💪 Full Stack Java Developer Expertise ✔️ 20+ years of Java development 100 successful projects using Java, Spring Boot, Spring Security, Hibernate, and enterprise architectures ✔️ Full Stack Development covering backend architecture database design frontend implementation and React Native mobile applications ✔️ Spring Boot Development, REST API microservices cloud-native applications and high-performance backend systems ✔️ Backend Architecture, distributed systems, 50 third-party integrations, authentication systems, and secure API development ✔️ PostgreSQL MySQL Redis AWS Docker Kubernetes CI/CD performance optimization and legacy system modernization ✔️ Extensive experience designing business-critical applications where scalability, maintainability, security, and long-term growth are key requirements ✔️ Experience integrating payment gateways, healthcare systems, cloud services, identity providers, and external enterprise platforms ✔️ Strong understanding of software architecture, design patterns, clean code principles, and modern development practices ✔️ Experience leading technical initiatives, collaborating with distributed teams, participating in code reviews, and helping businesses make technology decisions 🏥 Healthcare Software Development Expertise As a Senior Java Developer and Full Stack Developer, I've built secure and HIPAA-compliant healthcare software for startups, clinics, and digital health companies. ✔️ 100+ healthcare applications including EHR/EMR systems, telemedicine platforms, patient portals, and engagement solutions ✔️ 80+ FHIR & HL7 integrations for healthcare interoperability and secure data exchange ✔️ 150 React Native healthcare apps with Apple HealthKit, Google Fit, BLE, and real-time health monitoring ✔️ 100+ healthcare features delivered, improving patient engagement and clinical workflows ✔️ 50+ HIPAA-compliant architectures with encrypted storage, audit logging, RBAC, and secure APIs ✔️ 100 Java Spring Boot backend systems with up to 99.9% uptime ✔️150+ healthcare workflow automations, provider portals, appointment management, and patient communication platforms 💳 Fintech Software Development Expertise As a Full Stack Java Developer I've built PCI DSS-compliant fintech platforms focused on payments, identity verification, and transaction security. ✔️ 50+ Stripe, Apple Pay, Google Pay, and 3D Secure (3DS) integrations ✔️ 20+ KYC & AML workflows for onboarding and compliance automation ✔️ 100+ payment features delivered, reducing friction and improving transaction success ✔️ 25+ payment platforms, transaction systems, and financial API integrations ✔️ 15+ PCI DSS architectures with encryption, tokenization, audit logging, and secure authentication ✔️ 50+ financial reporting, payment workflows, transaction monitoring, and compliance solution 🏆 Key Results | Java Developer Spring Boot | Full Stack Java Developer | React Native ✔️ 20+ years of commercial experience as a Full Stack Java Developer ✔️ 100+ enterprise projects across Healthcare, FinTech, SaaS, and AI ✔️ 55+ AI-powered products using OpenAI, Claude API, FastAPI, AI Agents & RAG ( use Lovable \ Bollt.new \ Base44 and etc ) ✔️ Up to 100% uptime for mission-critical healthcare and fintech systems ✔️ Up to 40% higher patient engagement through digital health solutions ✔️ Up to 25% lower payment decline rates with optimized payment workflows ✔️ Up to 35% faster application performance and scalability improvements ✔️ Up to 90% fewer security vulnerabilities with secure architectures 📩 Looking for a technical partner who understands both technology and business goals? I help companies build, scale, and modernize Healthcare Fintech SaaS and Enterprise products using Java Spring Boot Full Stack technologies and React Native

I started his career as a programmer in Delphi, I work more than 15 years. There are also skills in C # (winforms) . (MSSQL, Oracle, MySQL, SQLite, PostgreSQL), also has skills with api functions, sound, theards etc. Working with REST API, like Elation, SureScript. Wrote simple backend server. Mobile develop on Delphi and Kotlin Compose. Have skill with https, ftps, sftp (etc) protocols.

Senior Full-Stack Developer • Performance Optimization Expert Java, Kotlin, JavaScript (frontend/backend), C++, Python, PHP, Perl SQL/NoSQL, Web/Desktop apps, Automation, Web Scraping I help companies make their software faster, lighter, and more efficient. 20+ years of hands-on experience in system performance tuning, profiling, solving bottlenecks, and refactoring legacy systems. If your application is slow, unstable, memory-hungry, or needs deep analysis — I can fix it. ⸻ 🧩 My Core Expertise • Performance optimization (Java/JVM, databases, backend services) • Query optimization, memory leak detection, code profiling • Refactoring legacy code, stabilizing old systems • Full-stack development (Java/Kotlin + JS, Python, PHP, Perl, C++) • Web automation & scraping • Systems analysis, debugging, complex issue resolution ⸻ 🚀 What I Deliver • Faster request processing • Reduced memory & CPU usage • Significantly improved database performance • Clean, maintainable, well-structured code ⸻ 🤝 Availability Open to long-term or part-time collaboration (30–40 h/week). Also interested in innovative startups: your idea — my implementation. ⸻ Let’s make your software fast, stable, and scalable!

I am a seasoned software developer with over 10 years of experience specializing in Backend and Full-Stack development. I pride myself on my excellent problem-solving skills and have a strong passion for writing clean and testable code. Clear communication is one of my strengths, making me a valuable team member in any software development project. Preferred Tech Stack: Backend: Java, Spring Boot, Thymeleaf, REST API, PostgreSQL, AWS, Linux, Tomcat, Nginx Frontend (Web): HTML, CSS, Sass, Javascript Frontend (Mobile): Flutter, Dart Cross-Platform: Flutter, Dart I am also proficient in the following technologies: Languages: Java, Scala, Groovy, Kotlin, Golang, JavaScript, TypeScript, Python, Dart, SQL Databases: PostgreSQL, MySQL, Oracle, Cassandra, MongoDB, SQLite, Neo4j Frameworks (Backend): Spring Boot, Spring Security, OpenAPI, Kafka, Zookeeper, Grails Frameworks (Frontend): Angular, React, Flutter, jQuery, Bootstrap Security: Spring Security, OAuth, JWT Technologies: HTML, CSS, JSON, XML, REST API API: REST API, OpenAPI, Swagger Messaging: Kafka, ActiveMQ, RabbitMQ Search: ElasticSearch, Lucene, Kibana Logging: ElasticSearch, Logstash, Kibana Cloud Providers: AWS, Google Cloud Testing: JUnit, Mockito, TestNG, Selenium, Cucumber, Katalon Studio Development Tools: Intellij IDEA, VSCode, Android Studio

👋 Hey everybody and welcome to my Upwork space! I’m an experienced Java developer who’s working with the up-to-date and most effective technologies. To ensure the highest quality standards, I tend to adhere to best coding practices. I continue to improve my skills and already know that the best way to learn something new and evolve as a professional is to work on the projects as a part of a team. I'm open to small and mid-size projects. Very communicative and easy-going. Ready for any skills evaluation, test task, technical interview. My tech stack: ▪ Backend: Java ▪ Frontend: Angular, React, HTML/CSS ▪ Frameworks: Spring Framework (SpringMVC, Spring Boot, Spring Data, Spring Security), Camunda 7 & 8 (Tasklist API, Operate API, Zeebe API, Web Modeler API) ▪ ORM: Hibernate ▪ Testing: JUnit, Mockito ▪ VCS: Git(GitHub, GitLab) ▪ Relational databases: MySQL, PostgreSQL, MariaDB ▪ NoSQL databases: MongoDB, Redis, DynamoDB, CosmosDB ▪ Build automation tools: Maven, Gradle ▪ API documentation tools: Swagger ▪ Clouds: AWS, Cloudinary–basic ▪ CI/CD: Jenkins ▪ IDE: IntelliJ IDEA ▪ Other: REST API, Design Patterns, Log4j 2, Lombok, Thymeleaf, Jakarta Servlet, JSP, JSTL, Guava, Groovy, Web Sockets, PDFsharp Workflow: - Agile, Kanban, Scrum - GIT, SVN (bitbucket/github/gitlab) - Jira, Trello, Asana, Assembla, Basecamp, ProjectPlace. I am up to long-term and full-time collaboration, so if you need a talented dev with technical background, feel free to drop me a line any time!