David

Contact
[open contact info](look above in the "contact info" section)
David Guseinov
Java Backend Engineer | Spring Boot | Microservices | SQL | IoT &
[open contact info](look above in the "contact info" section) Smart Systems | Open to EU Remote Roles
guseinov (LinkedIn) Spain
github.com/00liberty00 (Portfolio)

Top Skills
Summary
Java I am a Java Backend Developer with 5 years of freelance experience
Web Development developing business automation software and backend systems.
IoT
I have developed real-world applications used in shops, cafes,
Languages beauty salons, and car wash businesses. My work includes
English (Limited Working) designing system architecture, implementing business logic, working
Ukranian (Native or Bilingual) with databases, and deploying applications.

In addition to backend development, I have experience in IoT
and smart home systems, including designing and implementing
automation systems using protocols such as KNX, Modbus, and
MQTT.

My technical stack includes:

Java
Spring Boot
Hibernate / JPA
MySQL
Docker
Maven
Git
JWT Security

I enjoy solving real business problems and building reliable, scalable
systems.

Currently, I am looking for a remote Java Backend Developer
position where I can contribute to backend development and system
design.

Experience
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T-Smart
Smart Home Systems Engineer (KNX / Buspro)
January 2025 - November 2025 (11 months)
Crimea, Ukraine

• Designed and implemented smart building automation systems for residential
and commercial properties
• Configured and programmed KNX and Buspro controllers
• Integrated lighting, HVAC, security, and multimedia systems
• Worked with system architecture, wiring topology, and device configuration
• Diagnosed and resolved integration issues between hardware and software
components
• Collaborated with contractors, electricians, and clients to deliver customized
automation solutions
• Improved energy efficiency and operational convenience through automation
scenarios

School Maliy Mayak
Computer Science & Mathematics Teacher
September 2023 - January 2025 (1 year 5 months)
Crimea, Ukraine

• Taught Computer Science and Mathematics to students of different levels
• Developed structured lesson plans and educational materials
• Explained complex technical and mathematical concepts in a clear and
practical way
• Prepared students for exams and олимпиадного уровня задач
• Mentored students in programming fundamentals and algorithmic thinking
• Fostered analytical thinking and problem-solving skills

Freelance / Contract
Java Backend Developer (Freelance / Contract)
November 2011 - January 2025 (13 years 3 months)
Crimea, Ukraine

• Designed and developed backend systems for retail stores, cafés, and small
service businesses
• Built RESTful APIs using Java and Spring (Spring Boot)
• Designed and optimized relational databases (MySQL)
• Implemented business logic for sales management, inventory tracking, and
reporting
• Automated accounting and operational workflows to improve business
efficiency

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• Integrated backend systems with POS hardware and external services
• Refactored legacy code and improved system stability and performance
• Communicated directly with business owners to gather requirements and
deliver tailored solutions
• Reduced manual accounting time by 40%
• Served 5+ active businesses
Additional Commercial Projects

Beauty Salon Management System

Developed a desktop-based management system for beauty salons
Implemented client booking functionality
Designed inventory tracking for cosmetic and consumable materials
Integrated scheduling logic for service management
Built using Java, Hibernate, and MySQL

Car Wash Management System

Developed booking management software for car wash businesses
Implemented tracking of consumable materials and services
Designed workflow management for customer scheduling
Built database-driven logic using Hibernate and MySQL

Customer Loyalty QR Card Generator

Developed software for generating QR-based loyalty cards
Created digital cards compatible with Google Pay
Implemented customer registration and card generation workflows
Automated QR code generation and data storage

Telegram Notification Bots

Developed multiple Telegram bots for business notifications
Implemented automatic alerts for customer registration events
Integrated bots with backend systems
Used bot APIs for message automation and customer communication

Internet-club Air-net
Infrastructure / System Administration
September 2009 - January 2011 (1 year 5 months)

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Crimea, Ukraine

• Installed and configured 50+ workstations from scratch for a computer club
environment
• Deployed and maintained Linux (Ubuntu) and Windows operating systems
• Installed, configured, and optimized gaming software and office applications
• Managed user accounts, permissions, and system updates
• Diagnosed and resolved hardware and software issues
• Configured local network infrastructure and ensured stable connectivity
• Performed system monitoring, troubleshooting, and performance optimization
• Provided ongoing technical support and maintenance

Education
Tavrija National University
Master of Computer Applications (MCA), Developer · (2002 - 2008)

National 'Jaroslav the Wise' Law Academy of Ukraine, Simferopol
Average Technical, Lawer · (2007 - 2010)

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