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Kyiv, 04108 Mobile phone: [відкрити контакти](див. вище в блоці «контактна інформація»)
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Leonid Belyasnik
C++ Developer
Expertise Profile
Summary
C++ developer with commercial experience in software development, maintenance and
integration of client-server and distributed systems.

Experienced in C++ development for Windows and Linux, multithreading and
concurrency, networking and communication protocols, device integration, Qt/QML
applications, databases and supporting infrastructure.

Experience includes device management software, banking and payment systems,
security and cryptography software, REST services, IPC, reusable C++ libraries and
desktop applications.

Core Skills
● Programming
C++, C++11/14/17

● Operating Systems
Windows, Linux

● Concurrency & Systems
Multithreading, concurrency, thread pools, synchronization, IPC, POSIX API

● Networking & Integration
TCP/IP, sockets, Unix domain sockets, REST, SSH, Protocol Buffers,
client-server systems

● Frameworks & UI
Qt, QML

● Databases
Oracle, Firebird, PostgreSQL, SQLite

● Build & Development Tools
CMake, Git, Visual Studio, Qt Creator, CLion

● Testing
Automated testing

● Other
Cryptography, database encryption, device integration

Professional
Experience Developex — Kyiv
C++ Developer
Jan 2019 – Present

● Developing and maintaining software for managing and supporting various
hardware devices.

● Participated in the development of an integration layer for a new ecosystem of
DIY hardware devices within an existing system.
● Added support for new device types and protocols according to the existing
architecture.
● Extended the internal command-based protocol with new GET/SET operations
and implemented their command handlers.
● Implemented device-specific functionality across controller and model layers,
including communication with devices and models used by the application UI.
● Extended and improved existing base classes where required to support new
functionality.
● Developed a large set of Qt/QML UI components, from common controls such
as buttons, popups and input fields to more complex application-specific
components.
● Introduced a plugin-based approach for UI extensions and developed plugins
for the application.
● Implemented specialized UI components, including components involving
shader program loading.
● Developed reusable C++ libraries providing common and helper functionality.
● Developed the client application for an internal package management tool
using C++ and Qt/QML. The application provided a UI for inspecting available
package files, retrieving their metadata and defining the file composition of
installation packages. Communication with the server component was
implemented over SSH.
● Wrote and maintained automated tests.
● Implemented new functionality, maintained existing code and fixed bugs.

Technologies: C++, C++17, Qt, QML, CMake, Git, SSH

Comodo Group — Kyiv
C++ Developer
Aug 2017 – Dec 2018

CCS for Linux

● Developed and maintained the Linux version of the Comodo security product.
● Reworked the main Linux daemon, removing its dependency on Qt.
● Implemented daemon functionality using worker threads and a
condition-variable-based task pool.
● Worked with the existing IPC mechanism based on Unix domain sockets and
Protocol Buffers.
● Developed and maintained client-side components and supporting tools.
● Implemented new functionality and fixed issues in the existing C++/Linux
codebase.

Technologies: C++, Linux, POSIX API, multithreading, Unix domain sockets, Protocol
Buffers, Qt, CMake, Git

Provectus
C++ Developer
Jul 2017 – Jan 2018 (Part-time / additional project)

DeviceManager

● Initiated development of a service for exposing data from a hardware
communication layer to web clients.

● Researched different implementation approaches and libraries and selected
Microsoft's C++ REST SDK for the REST API.
● Designed and implemented the initial service framework, establishing the
technical approach for the project.
● Implemented communication between the service and an existing hardware
communication library while providing REST API endpoints for client requests.

Technologies: C++, C++ REST SDK, REST, networking, distributed systems

Cipher Company — Kyiv
C++ Developer / Lead Project Engineer
Mar 2013 – Aug 2017

Worked on banking, security, cryptography and payment-processing software.

● Developed and maintained banking client applications for operators.
● Developed and maintained banking gateway applications for scheduled and
automated integration with external banking and payment-processing systems.
● Developed a separate customer monitoring system, primarily using Oracle and
stored procedures.
● Participated in testing and evaluation of an in-house cryptographic library,
including developing usage examples and validating its functionality.
● Researched and implemented approaches for Firebird database encryption
based on the company's cryptographic library.
● Developed Firebird 3.0 encryption plugins and supporting components.
● Developed a prototype database encryption system integrating encryption at
the database/plugin level. The technology was researched and presented as a
potential solution but was not commercially deployed.
● Developed a PHP extension integrating the company's cryptographic library.
● Developed and maintained banking gateway and integration modules.

Technologies: C++, Delphi, C++Builder, VCL, Embarcadero RAD Studio, Oracle,
Firebird, PHP, cryptography, OpenSSL, TCP/IP, multithreading, Windows API, Linux

Intellect-Service — Kyiv
C++ Developer
Mar 2012 – Feb 2013

● Maintained and extended existing C++ applications used for accounting and
reporting.
● Implemented new functionality and fixed bugs across several products,
including BEST ZVIT+, M.E.Doc and IS-Pro.
● Gained hands-on commercial experience working with large existing C++
codebases.
● Developed a C++ console application for sending developer notifications via
XMPP.

Technologies: C++, C++Builder, VCL, SQL, Firebird

Ukrtelecom JSC — Shostka
Software Engineer
Sep 2008 – Feb 2012

● Developed a Delphi-based operator application for remote management and
monitoring of Internet club computers via Telnet.
● Implemented remote enable/disable controls and status monitoring for client
workstations.
● Developed a prototype web-based system for registering and tracking Internet
connection requests.
● Set up and deployed the prototype application on an internal network server.
● Provided system administration and technical support for the branch network
and related equipment.

Technologies: Delphi, Telnet, Windows, web technologies

Earlier experience
Self-employed / Freelance
Apr 2008 – Feb 2009
Computer equipment service, maintenance and repair.

PSC Prominvestbank
Apr 2008 – Sep 2008
Automation, system administration, branch network support and ATM maintenance.

Private Enterprise Arkhistyl
Jul 2006 – Sep 2007
Automation tools and system administration.

Personal Project HomePowerGuard

C++ Backend & ESP32 Firmware | 2026 – Present

GitHub: https://github.com/leonid-belyasnik/inverter-monitor

Developing a personal project for monitoring a hybrid solar inverter, combining
embedded firmware, C++ backend services and a web-based telemetry dashboard.

● Developing firmware for an ESP32-based device that reads inverter data via
Modbus RTU over RS-485.
● Building a C++ backend using Boost.Asio/Beast, MQTT, PostgreSQL, REST
API and WebSocket.
● Integrating telemetry with a React/TypeScript dashboard.

Technologies: C++20, ESP32, Modbus RTU, RS-485, Boost.Asio/Beast, MQTT,
PostgreSQL, REST, WebSocket, Docker.

Additional ● Oracle and Firebird database installation and configuration.
technical ● Creation of isolated test databases and synthetic data for testing banking
experience software without access to production databases.
● Setup and configuration of supporting services and infrastructure for
development and testing environments.

● Experience setting up mail servers and other services to emulate production
environments.

Education Sumy State University

Specialist Degree in Informatics (Mathematician Developer)

2003 – 2009

Languages English: Intermediate

Ukrainian: Native

Russian: Native