Sergey Khlebnikov, Developer in Almaty, Almaty Province, Kazakhstan
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Sergey Khlebnikov

Verified Expert  in Engineering

Full-stack Developer

Almaty, Almaty Province, Kazakhstan
Toptal Member Since
February 12, 2018

Sergey is a software engineer with a computer science degree and six years of hands-on experience in different areas of the IT industry. As a full-stack developer, he's been involved in developing complex business web applications. He's also worked on mobile solutions for business and productivity sectors from low-level to UI. He's passionate about new technology and has been a Kotlin enthusiast since the alpha version of this language.


Toptal Client
JavaScript, Node.js, React, Data Visualization, Full-stack, Bash, Google Cloud...
Xored Software, Inc.
PostgreSQL, Oracle SQL, Node.js, Flux, React, JavaScript, Hibernate, Spring...
SQLite, Android NDK, Android SDK, JNI, Cocoa, CSS, HTML, JavaScript, ASP.NET...




Preferred Environment

Git, IntelliJ IDEA, Visual Studio Code (VS Code), Linux

The most amazing...

...thing I've coded is a library for creating self-learning virtual entities. It's based on an alternative experimental approach to machine learning.

Work Experience

Full-stack Developer

2018 - PRESENT
Toptal Client
  • Created a data visualization portal and delivery management system from the ground up.
  • Unified several reporting systems and formats under an extensive internal data schema.
  • Implemented a wide array of queries for data charts and metrics.
  • Implemented both generic and service-specific content delivery protocols.
Technologies: JavaScript, Node.js, React, Data Visualization, Full-stack, Bash, Google Cloud, Google BigQuery, Google App Engine, Kotlin, Python, APIs

Software Engineer

2014 - 2017
Xored Software, Inc.
  • Supported a data-aggregation software based on an application with a huge legacy codebase.
  • Extracted UI parts of the codebase to improve modularity and ease the compilation process.
  • Performed an upgrade of an existing front-end codebase, including upgrading the dependency packages with major versions, and made various adjustments for the project to work with breaking changes.
  • Supported a web application for lab management as a full-stack developer.
  • Implemented the execution scheduling of event-triggered customizable tasks for a lab-management application.
Technologies: PostgreSQL, Oracle SQL, Node.js, Flux, React, JavaScript, Hibernate, Spring, Enterprise Java Beans (EJB), Java EE, Web App Development, Full-stack, Java, Git, Back-end, Front-end, Linux, Regex, Agile Software Development, CSS, REST APIs, SQL, NPM, Scrum, XML, Jenkins, Jira, GitLab, HTML5, Dojo, Less, React Router, Imperative Programming, Object-oriented Programming (OOP), IntelliJ IDEA, Data Structures, Regular Expressions, RESTful Development, JVM, JSON, SourceTree, REST, Apache Maven, Object-oriented Design (OOD), Zsh, Networks, Multithreading, Shell, Model View Controller (MVC), Vim Text Editor, Continuous Integration (CI), Asynchronous Programming, Confluence, Markdown, Lodash, Trello, Webpack, TestNG, Code Review, APIs

Software Engineer

2011 - 2014
  • Created a full-working Android (2.2) application and handed it over to the customer with additional support.
  • Improved the performance of an Objective-C read-write framework by porting it to C++; it also gave the client the possibility of using it as a cross-platform library.
  • Reverse-engineered missing parts of an encryption protocol of a OneNote file format and enabled a proper implementation.
  • Created an application prototype with documented Android (3.0) platform architecture. Android NDK was used to attach low-level frameworks to the application.
  • Supported an operating system X desktop application for note-taking.
  • Integrated geolocation support via Google Maps API into the web application.
  • Supported a very old and complex C# application and developed one of the web-based modules for it.
Technologies: SQLite, Android NDK, Android SDK, JNI, Cocoa, CSS, HTML, JavaScript, ASP.NET, Microsoft SQL Server, Java, C#, Objective-C, C, C++, Web App Development, Full-stack, Back-end, Front-end, Agile Software Development, SQL, Windows, Scrum, XML, C++11, Android, Microsoft Visual Studio, iOS, HTML5, Less, Xcode, Google Maps API, jQuery, Knockout (Knockout.js), Imperative Programming, Object-oriented Programming (OOP), IntelliJ IDEA, Data Structures, SourceTree, Apache Maven, Object-oriented Design (OOD), Multithreading, Reverse Engineering, Model View Controller (MVC), Subversion (SVN), GCC, OS X, Microsoft OneNote

Kotlin Implementation of a PCG Algorithm
A lightweight JavaScript and Java Virtual Machine cross-platform and easy-to-use implementation of several members of the PCG family of pseudo-random number generators.

PCG is a family of simple, fast. space-efficient, and statistically good algorithms for random number generation. Unlike many general-purpose RNGs, they are also hard to predict.

Spirent Velocity
Spirent Velocity is an integrated lab management and test execution solution for elastic test labs. It coordinates, orchestrates, manages, and monitors physical and virtual environments, as well as facilitates lab consolidation.

Designed for testers and developers of every skill level, it provides a simple user experience for defining a testbed topology that can be used to execute a single test case or an entire test plan. Its drag-and-drop interface allows testers to quickly create and execute complex test scenarios, while its multi-user reservation system prevents resource conflicts even with teams spanning multiple continents.

Enterprise Network Management System

A single integrated solution for complete lifecycle management of routers, switches, and wireless devices, along with
deep visibility into end-user connectivity and application performance. It can manage global enterprise networks that
have thousands of network devices and hundreds of thousands of access devices.

Kotlin Implementation of Repacker for w3speech Files

A Kotlin-written application for packing and unpacking w3speech audio files.

This was done to replace the audio tracks while in the game. It is supposed to be used with several third-party applications for the actual audio recording and processing.

Gorillized Outline

A OneNote app for offline, cloud, and WebDAV. It's OneNote compatible and Office 365 powered.

Capture notes at any spot on a page and drag those notes around. This app organizes notes in the world's most natural hierarchy. It stores notes in your local file system and can be synced across devices with your favorite cloud.

You can use it to import data from Evernote and Circus Ponies.

Kotlin Library for Searching Paths in a Graph

A small library, written in pure Kotlin, for searching various paths between nodes in a graph.

As part of a research project, this library enabled an easy solution for a rule-based self-learning entity to perform quite well.

ARMS Report Center
With ARMS Report Center, you have access to over 300 canned reports as well as the power to create your own, whether in the office or on the go. As a browser-based solution, the Report Center allows you to run, save, and print reports from anywhere you have an internet connection.

ARMS Computer Aided Dispatch

ARMS Computer Aided Dispatch provides standard features like standard operating procedures, officer safety alerts, and unit dispatches, allowing dispatchers to manage their officers and fleet effectively. ARMS is built on Microsoft's .NET and SQL Server technology and is completely integrated with all other ARMS modules.

ONE, Inc. SalesOne® | Android

This CRM solution allows insurance companies and general agencies to manage their marketing representatives and producer relationships more effectively. SalesOne® allows you to remotely manage your customers and sales force via a web interface. By integrating communication, tracking, and reporting, SalesOne® drives efficiency and productivity.
2011 - 2015

Master's Degree in Computer Science

Novosibirsk State University - Novosibirsk, Russia

2007 - 2011

Bachelor's Degree in Computer Science

Novosibirsk State University - Novosibirsk, Russia


Node.js, React, REST APIs, Lodash, Google Maps API, jQuery, React Router


Git, IntelliJ IDEA, Apache Maven, Gradle, SourceTree, Zsh, NPM, BigQuery, cURL Command Line Tool, Vim Text Editor, Shell, GitLab, GCC, Trello, Subversion (SVN), Microsoft Visual Studio, Webpack, Android NDK, Bitbucket, Jenkins, Confluence, Xcode, Jira, Mercurial, GitHub


JavaScript, Kotlin, Java, Regex, SQL, HTML, C++, C, C#, CSS, AspectJ, Bash Script, Markdown, C++11, Sed, XML, Clojure, HTML5, Less, Objective-C, Bash, Python


Imperative Programming, Object-oriented Programming (OOP), RESTful Development, Declarative Programming, REST, Functional Programming, Object-oriented Design (OOD), Agile Software Development, Continuous Integration (CI), Scrum, Model View Controller (MVC), Asynchronous Programming, Aspect-oriented Programming, Procedural Programming, Object-oriented Analysis & Design (OOAD)


JVM, Linux, Ubuntu, Google App Engine, Visual Studio Code (VS Code), Java EE, JavaFX, Debian, Android, Windows, iOS, OS X, Heroku


Relational Databases, JSON, PostgreSQL, Google Cloud, Google Cloud Storage, SQLite, Microsoft SQL Server, Oracle SQL, H2, Databases


Flux, JNI, Cocoa, JUnit, Swing, Dojo, Ktor, Knockout (Knockout.js), TestNG, Hibernate, Spring, ASP.NET, Android SDK


Web App Development, Full-stack, Back-end, Front-end, Regular Expressions, Data Structures, Algorithms, Google BigQuery, Data Visualization, Code Review, APIs, Networks, Ajax, Multithreading, Reverse Engineering, Semantic UI, Enterprise Java Beans (EJB), Linear Algebra, Mathematical Analysis, Mathematical Logic, Differential Equations, Graph Theory, Discrete Mathematics, Decision Modeling, Microsoft OneNote, Random Number Generation

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