Denis Tsybulia

My experience

1. Since 1995 when I started my computer science study at the University of Alabama in USA I am entirely in the programming in different fields of computerized system development on different platforms.
2. 27 years, 30 project, including 18 individual and 12 big corporate team projects

Fields of expertise

1. web application development
2. database design and maintenance
3. desktop applications for accounting, warehouse and business control and operations
4. embedded systems
5. equipment control systems

Web-programming

1. In 2008 I decided to switch to the web programming and took PHP as my major web technology.
2. Later In 2012-2013 when web programming grew in complexity, I took Yii PHP framework as a main technological stack for my career.
3. Since that time main focus shifted to the web technologies

Achievements

1. 7 big team collaborations on scalable advanced corporate projects
2. 9 individual projects for the customers in different industries
3. 6 working multipurpose web-based systems of my own architecture and implementation

PHP technological environment

Story

1. There was some period of building static web resources on pure HTML with Javascript implementation.
2. I started in 2008 with the PHP 5.6 version for small dynamic web-site construction
3. In 2013 the necessity in more robust instrument brought up the need for PHP framework utilizing.
4. Yii and later Yii2 frameworks became my major platform for production development
5. Since 2019, I have actively participated in numerous projects utilizing PHP 7.4, applying its features to build efficient and scalable solutions.
6. I learned and built some individual projects on Laravel PHP framework. Later I took part in 2 commercial team projects with this framework.
7. For the last 2 years, I have been working with Symfony on individual projects, leveraging its powerful features and best practices.
8. In my practice I usually follow the SOLID principles of development with the use of design patterns
9. Recently I took part in the projects on PHP 8 with the implementation of technologies like Memcached, Redis, ElasticSearch

Project Types

1. Official sites
2. Enterprise control system
3. Business performance management
4. Internet platforms for medical care
5. CRM systems
6. online marketplace
7. Sale calculations
8. ERP systems
9. Web store platform
10. Affiliate network platform

Features I implemented

1. Import/Export Excel/XML/CSV
2. PDF generation
3. Shopping Cart for online ordering
4. Email sending
5. CRUD with filtering, sorting, pagination
6. QR code generation
7. Customer registration and access control
8. Composer implementation
9. RESTful API
10. Google and Yandex map API
11. Automated application deployment
12. Google and Facebook SSO

1. For last 5 years I extensively use Laravel as my preferable framework.
2. I was impressed by the invincible advance of this system. How quickly it came by the leading role in the PHP technological industry.
3. I like to employ the most auspicious technologies that this framework provides. Often incorporate Laravel elements in the other technological environments.

My favorite features

1. Service container
2. Service and model injection
3. Middleware for permission control
4. Resources for REST API
5. Single method controller

Symfony Framework experience

1. For the last 3 years, I have been working with Symfony on individual projects, leveraging its powerful features and best practices.
2. MVC Architecture – Utilizing Symfony’s structured approach to keep code clean, scalable, and maintainable.
3. I like to employ Doctrine ORM! Its powerful entity management, seamless migrations, and flexible repositories make database interactions both efficient and enjoyable.
4. Symfony Console – Automating tasks, running commands, and handling cron jobs

My favorite features

1. Security & Authentication – Implementing user authentication using Symfony Security (JWT, OAuth, API Token)
2. RESTful API Development – Building robust APIs with Symfony’s API Platform and serializer component
3. Event Dispatcher & Listeners – Managing event-driven logic for modular application design
4. Dependency Injection – Structuring services for decoupled and testable code
5. Testing with PHPUnit – Writing unit and functional tests for high-quality software
6. Integration with Third-Party APIs – Connecting to external services like payment gateways, email providers, and social logins
7. Dockerized Symfony Development – Running Symfony applications in Docker containers for consistent environments

Javascript

1. Extensive experience with vanilla JavaScript, DOM manipulation, and event-driven programming
2. Many technologies, extensive use of jQuery UI and components were employed.
3. Strong skills in optimizing performance and rendering, including lazy loading, code splitting, and caching strategies.
4. Experience with integrating third-party APIs such as Google Maps API, Facebook SDK, and payment gateways.
5. Managing asynchronous operations with Promises, async/await, and event-driven architectures.

Typescript

1. Developing scalable and maintainable applications using TypeScript, ensuring type safety and enhanced code quality.
2. Using TypeScript with Vue.js, Node.js, and frontend frameworks for structured development.
3. Extensive experience with Vite for ultra-fast frontend builds, live reloading, and modern JavaScript/TypeScript support.
4. Using npm/yarn for dependency management and script automation.
5. Implementing tree shaking, code splitting, and ES modules for optimized frontend performance.

In my frontend development

1. I have extensive experience using the Bootstrap framework for responsive and mobile-first web development.
2. It has been an integral part of my frontend projects, providing a consistent, structured approach to UI design built on the responsive web design principles.
3. Proficient in Bootstrap’s grid system, utilities, and component-based development.
4. Utilizing AdminLTE, a powerful Bootstrap-based admin panel, for dashboards with widgets, charts, tables, and user management interfaces.

Js integrations

1. Experience with Bootstrap JavaScript components, such as modals, carousels, tooltips, and accordions.
2. Integrating Bootstrap with jQuery and Vue.js for dynamic UI elements.
3. Recently had some experience with Tailwind CSS
4. Optimizing page performance by using only required Bootstrap modules instead of the full library..

SOLID Principles:

1. Single Responsibility Principle (SRP): Ensures that each class has one reason to change, making the code more maintainable.
2. Open/Closed Principle (OCP): Classes should be open for extension but closed for modification, promoting scalability and flexibility.
3. Liskov Substitution Principle (LSP): Derived classes must be substitutable for their base classes without affecting correctness.
4. Interface Segregation Principle (ISP): Clients should not be forced to depend on interfaces they do not use.
5. Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules, but both should depend on abstractions

Design Patterns:

1. Creational Patterns: Deal with object creation mechanisms, such as Singleton, Factory, and Builder, to make systems more flexible and reusable.
2. Structural Patterns: Focus on how objects and classes are composed to form larger structures, like Adapter, Facade, and Proxy.
3. Behavioral Patterns: Focus on communication between objects, such as Observer, Strategy, and Command, to simplify object interactions.

Database management systems

1. Almost all projects I worked on required use of database
2. I had experience of database implementation even before I started web application development.
3. Long period of extensive use of SQL for database maintenance.

Database management systems

1. dBase, FoxBase since 1995 for several years
2. MS Access since 1999 for desktop applications
3. SQL Server in some projects since 2005
4. PostgreSQL in 2003 in ATIS project
5. MySQL since 2009 up to now
6. PostgreSQL in 2023

high-performance in-memory data store

1. Redis
2. Elasticsearch
3. Memcached

NoSQL database

1. MongoDB
2. Google BigQuery

I worked on software for

1. Psychological Help
2. Real Estate
3. Electronic Device Repairement Service
4. Hotel and Appartment Rent
5. Hygiene Product sales
6. Tourist Guide Service
7. Tour Sale Platform
8. Electronic equipment production
9. QR-code trading
10. Affiliate network
11. Advertising agency
12. Orthopedic and medical product distribution

Project Types

1. Official sites
2. Enterprise control system
3. Business performance management
4. Internet platforms for medical care
5. CRM systems
6. online marketplace
7. Sale calculations
8. ERP systems
9. Web store platform
10. Affiliate network platform

affiliate marketing platforms for managing and optimizing performance marketing campaigns

1. Google Ads
2. Facebook Ads Manager
3. Everflow

lead distribution and performance tracking platform

1. Google Analytics
2. Facebook Business Manager
3. Facebook Insights
4. Leadspedia
5. HasOffers

Implemented Corporate Information Systems

1. Built applications from the ground up based on customer-specific requirements.
2. Designed scalable and flexible architectures to accommodate future growth
3. Designed and integrated solutions tailored to enterprise-level needs
4. Applied industry best practices to ensure reliability, security, and maintainability
5. Provided System Integration and Data Migration
6. Optimized System performance

Maintaining and Enhancing Legacy Systems

1. Continued development and support for long-running projects with outdated codebases
2. Refactored and optimized existing systems while preserving core functionality
3. Migrated outdated platforms to more efficient and scalable architectures.
4. Connected new systems with existing corporate infrastructure and third-party services
5. Successfully connected various external services, APIs, and SaaS solutions
6. Ensured seamless communication between internal systems and third-party platforms

Implemented Corporate Information Systems

1. Built applications from the ground up based on customer-specific requirements.
2. Designed scalable and flexible architectures to accommodate future growth
3. Designed and integrated solutions tailored to enterprise-level needs
4. Applied industry best practices to ensure reliability, security, and maintainability
5. Provided System Integration and Data Migration
6. Optimized System performance

Maintaining and Enhancing Legacy Systems

1. Continued development and support for long-running projects with outdated codebases
2. Refactored and optimized existing systems while preserving core functionality
3. Migrated outdated platforms to more efficient and scalable architectures.
4. Connected new systems with existing corporate infrastructure and third-party services
5. Successfully connected various external services, APIs, and SaaS solutions
6. Ensured seamless communication between internal systems and third-party platforms

Features I implemented

1. Administrative panel
2. Import/Export Excel/XML/CSV
3. PDF generation
4. QR code generation
5. Google and Yandex map API
6. Google and Facebook SSO
7. Lazy loading
8. Mailgun integration
9. Worked with payment gateways, CRM platforms, marketing tools, and analytics services.

Functionality I developed

1. Shopping Cart for online ordering
2. Email sending
3. CRUD with filtering, sorting, pagination
4. Customer registration and access contol
5. Composer implementation
6. On-line payment
7. RESTful API
8. Automated application deployment
9. Ensured seamless communication between internal systems and third-party platforms

API technologies

Designing and developing RESTful APIs

1. Implementing authentication mechanisms such as OAuth, JWT, and API keys to secure APIs
2. Integrating third-party APIs like payment gateways (e.g., Stripe, Square, Mollies), social media logins (e.g., Facebook, Google), and email services (e.g., Mailgun)
3. Ensuring smooth data exchange through proper API versioning, error handling, and response formatting (JSON, XML)
4. Optimizing API performance through caching, rate limiting, and other strategies to handle high traffic and large datasets
5. Integrating with external services like CRMs, ERP systems, and marketing platforms to automate workflows and streamline processes
6. Documenting APIs using tools like Swagger or Postman to ensure ease of use and collaboration across teams
7. Maintaining API security by preventing vulnerabilities such as SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF)
8. I have solid experience working with GraphQL, including designing schemas, optimizing queries, and integrating GraphQL APIs into PHP-based backends and frontend applications.

Desktop applcations for

1. primary document development
2. operational and accounting control
3. business analysis tools and enterprise decision-making process
4. enterprise resource planning (ERP-system)
5. personnel management system
6. customers and counterparties service and contact maintenance
7. financial planning
8. software integration of business control systems with data exchange technology
9. Commerce, warehouse equipment (barcode scanners, cash registers, QR-code technology and so on.)

Platform and Technologies

1. Operating systems:
2. Windows 9 x, 2000, XP, NT
3. Linux
4. Database management systems:
5. MS Access, MS SQL Server
6. MySQL, PostgreSQL
7. Programming languages:
8. Visual basic
9. C++ MFC

Applcations for

1. I had an experience of 3 years working on the air traffic control system.
2. Within this project we developed and implemented the application that
3. maintatined radar and other equipment control
4. processed the signals from different communication sources
5. made graphic visualization of the aircraft traffic and airplane resource parameters
6. made complex calculations for tracking algorithm and geometric compute
7. provided operator control on the guided aircrafts

Platform and Technologies

1. Operating systems:
2. MS DOS, Windows
3. QNX 6.1 / Neutrino, Photon App Builder,
4. Database management systems:
5. PostgreSQL
6. Programming languages:
7. C++

Applcations for

1. I had an experience of 3 years working on the air traffic control system.
2. Within this project we developed and implemented the application that
3. maintatined radar and other equipment control
4. processed the signals from different communication sources
5. made graphic visualization of the aircraft traffic and airplane resource parameters
6. made complex calculations for tracking algorithm and geometric compute
7. provided operator control on the guided aircrafts

Platform and Technologies

1. Operating systems:
2. MS DOS, Windows
3. QNX 6.1 / Neutrino, Photon App Builder,
4. Database management systems:
5. PostgreSQL
6. Programming languages:
7. C++

Fluent English

1. I maintain my English since my year study in USA (University of Alabama)
2. Since that time I improve my language proficiency in my professional and private communications
3. During 15 years I worked in several companies where English was a language of communication
4. I worked with with employers and clients from USA, Finland, Germany, Brazil.
5. During all my working period I basically received and developed documentation in English.

Communication skills

1. During all my individual career I had to communicate with the product owner and sometimes top company management.
2. I consider my communication skills quite sold for dealing both with the business people and IT professionals.
3. I always try to sustain friendly style of relationships with colleagues and clients
4. Big experience of communication with people from different cultural and social environments is also my distinguishing trait.

Fluent English

1. During all my career as individual enterpreneur I had to communicate with the product owner and sometimes top company management.
2. Since that time I improve my language proficiency in my professional and private communications
3. During 15 years I worked in several companies where English was a language of communication
4. I worked with with employers and clients from USA, Finland, Germany, Brazil.
5. During all my working period I basically received and developed documentation in English.

Communication skills

1. During all my career as individual enterpreneur I had to communicate with the product owner and sometimes top company management.
2. I consider my communication skills quite sold for dealing both with the business people and IT professionals.
3. I always try to sustain friendly style of relationships with colleagues and clients
4. Big experience of communication with people from different cultural and social environments is also my distinguishing trait.