Vіtalіy S.
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Successful projects
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Language proficiency level
Українська: fluent
English: upper-intermediate
Skills and abilities
Programming
Portfolio
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AYB Serve Business Platform
AYB Serve Business Platform is an enterprise B2B monorepo built with Node.js and NestJS, designed around multi-tenancy and growth in concurrent usage. It uses a dedicated API gateway for routing, JWT validation, proxying to domain services, and OpenAPI exposure.
Backend: TypeScript, NestJS, Prisma, PostgreSQL, class-validator / class-transformer, Swagger/OpenAPI, JWT & OAuth-related flows, Argon2, KafkaJS, Socket.IO (+ Redis for scaling realtime), http-proxy-middleware on the gateway.
Frontend: Next.js, React, TanStack Query & TanStack Table, React Hook Form, Zod, Zustand, Tailwind CSS, Radix UI, FullCalendar, ApexCharts, drag-and-drop (Pangea DnD), Framer Motion, Socket.IO client.
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The platform is under active development; the long-term target is a fleet of ~30 domain microservices behind the gateway.
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Microservices-Based Bike Rental Platform (Backend on Java)
JavaA scalable bike rental platform built using a microservices architecture for both B2C and B2B use cases.
The system supports:
• End-user bike subscriptions and rentals
… • B2B partnerships (hotels, rental providers) with revenue sharing
• Automated recurring payments
• Real-time bike tracking and availability
Key Technologies & Architecture
• Java, Spring Boot, Spring Cloud
• Microservices architecture (Auth, Rental, Payment, etc.)
• Spring Cloud Gateway as a single entry point
• OAuth2 / OpenID Connect (JWT-based authentication)
• Kafka for asynchronous inter-service communication
• ElasticSearch for performance searching
• PostgreSQL + JPA, soft deletes, audit fields
• Redis for caching and token/session management
• Stripe integration for recurring and one-time payments
• Swagger / OpenAPI for API documentation
• Docker & Kubernetes for containerization and orchestration
• CI/CD-ready architecture (GitHub Actions)
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Telegram bot for group reservations of sports facilities (Node.js)
Javascript and Typescript
A Telegram bot for group reservations of sports facilities. Chat participants reserve time slots within their community; administrators configure the facilities, operating hours, booking window, and limits.
The backend is built on NestJS, data is stored in PostgreSQL via Prisma, and integration with Telegram is handled by Telegraf (nestjs-telegraf).
… The project demonstrates the full cycle: a domain-specific booking model that accounts for time zones, background tasks (booking statuses, reminders), and CI/CD with deployment to Docker on a VPS.
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Corporate website
Web Programming
Corporate website on WordPress for a Dutch company.
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Multi-Channel Marketplace Integration System (Back and Front on
JavaDeveloped a complex Java-based system using Spring Boot designed to automate data exchange between 1C (ERP system) and multiple online marketplaces such as eBay, Recar, and others.
The solution consists of two main applications:
… Backend Application
A centralized backend service responsible for:
• Receiving and synchronizing product, pricing, and inventory data from 1C
• Persisting and managing data in a relational database
• Applying complex business logic, validations, and transformations
• Integrating with external marketplace APIs
• Preparing and sending correctly formatted requests to different marketplaces
• Handling errors, retries, and marketplace-specific requirements
This backend acts as a unified integration layer that simplifies multi-marketplace operations and ensures data consistency across platforms.
Frontend Application
A separate Spring Boot application with a server-side UI built using:
• Thymeleaf
• JavaScript
The frontend provides:
• Administrative interface for managing products and marketplace settings
• Monitoring of synchronization status and marketplace responses
• Control over business processes and data flow
Technologies Used
• Java
• Spring Boot
• REST APIs
• Thymeleaf
• JavaScript
• Relational Databases (JPA/Hibernate)
• Integration with external systems (1C, marketplaces)
Business Value
• Automated product synchronization across multiple marketplaces
• Reduced manual work and human errors
• Scalable architecture for adding new marketplaces
• Centralized business logic and data management
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Telegram Chatbot for Order Management (Java)
Java
Developed a Telegram-based chatbot using Java to automate customer inquiries and order requests for a company specializing in leather products.
The chatbot acts as an interactive assistant that guides users through a multi-step questionnaire to collect detailed order information, significantly reducing the workload of sales managers.
… Key Features
• Interactive questionnaire flow with multiple decision branches and validation logic
• Support for complex product customization options
• File uploads (images, documents) directly through Telegram
• Integrated online payments using LiqPay
• Automatic order creation and structured data collection
• Real-time forwarding of completed orders to a dedicated Telegram managers’ group
• Notifications for managers about new requests and payment status
Manager Workflow Automation
All customer requests submitted via the chatbot are automatically sent to a private Telegram group used by managers.
This allows the team to:
• Instantly receive structured order data
• Review attached files
• Respond faster to customers
• Eliminate manual data entry and miscommunication
Technologies Used
• Java
• Telegram Bot API
• REST APIs
• Payment integration (LiqPay)
• File handling and storage
• Business logic for conversational flows
Business Value
• Streamlined order intake process
• Improved customer experience through guided interactions
• Reduced response time and operational costs
• Scalable chatbot logic for adding new products and flows
