Sergey is available for hire

Sergey Kolodiy

Verified Expert in Engineering

.NET Developer

Location

Almaty, Almaty Region, Kazakhstan

Toptal Member Since

October 27, 2014

Sergey is a software engineer with extensive development experience in the .NET technology stack, with strong architecture and coding skills. He loves to work on complex and business-critical tasks with full involvement, high productivity, and great enjoyment. He is a big fan of clean, testable, and maintainable code and has worked on a number of successful projects ranging from small startups to complex enterprise applications.

Back-end Debugging Web Development Full-stack Visual Studio .NET Microsoft Visual Studio C#C#.NET LINQ Unit Testing Microsoft SQL Server ASP.NET Web API ASP.NET .NET Core

Portfolio

Independent Project

C#, .NET 6, Telegram Bot API, Trading, Stock Price Analysis, .NET...

BoostLingo, LLC

JavaScript, C#.NET, AngularJS, .NET Core, Entity Framework Core, Web...

Shrader Group LLC

C#, .NET, Microsoft SQL Server, REST APIs, Entity Framework Core, ASP.NET Core...

Experience

C# - 15 years REST - 10 years Unit Testing - 10 years ASP.NET Web API - 9 years .NET Core - 8 years TypeScript - 3 years Algorithmic Trading - 2 years Microservices Architecture - 2 years

Availability

Full-time

Preferred Environment

Git, Visual Studio, Windows, .NET, Microsoft Visual Studio, C#, C#.NET, Visual Studio Code (VS Code), Full-stack Development, GitHub

The most amazing...

...application I've created is a tool that generates an OData REST API and a single-page web UI for any relational SQL database.

Work Experience

Software Engineer | Analyst

2019 - PRESENT

Independent Project

Designed and developed a successful algorithmic trading solution.
Implemented various data analytics algorithms and several trading strategies.
Integrated the solution with Telegram bot API for remote management.

Technologies: C#, .NET 6, Telegram Bot API, Trading, Stock Price Analysis, .NET, Microsoft Visual Studio, ASP.NET Web API, Unit Testing, REST, LINQ, .NET Core, Algorithmic Trading, Object-oriented Programming (OOP), C#.NET, Azure, Microsoft Azure, SQL, APIs, Task Analysis, Visual Studio, Back-end, REST APIs, CI/CD Pipelines, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Markdown, Functional Programming, Object-oriented Design (OOD), SQL Server Management Studio, Microsoft SQL Server, Design Patterns, Visual Studio Code (VS Code), Fiddler, Debugging, Mathematics, Software Architecture, Web API, API Integration, Agile, Web Development, Full-stack Development, Full-stack, GitHub, Solution Architecture, DevOps, Entity Framework, Performance, Back-end Architecture, Cloud Architecture, System Integration, Web Applications, Object-relational Mapping (ORM), Distributed Systems, .NET 7, Database Architecture, Data Structures, Cloud, Event-driven Programming, React, Event-driven Architecture

Senior Software Engineer

2018 - 2022

BoostLingo, LLC

Worked on new business-critical features in a fast-paced environment, fixed bugs, and refactored legacy code.
Worked on all aspects of the system, including business logic workflows implementation, task analysis, third-party systems and services integration, back-end APIs and web client development, and much more.
Made a performance audit and improved the performance of critical back-end APIs.
Implemented a bunch of useful ASP.NET Core extensions and middleware, such as online user tracking and CSP handling.
Achieved such exceptional project results with a Toptal client that I was bought out and started working with the client directly as a remote contractor.

Technologies: JavaScript, C#.NET, AngularJS, .NET Core, Entity Framework Core, Web, Twilio API, Twilio Programmable Video, Zoom, .NET, Microsoft Visual Studio, C#, ASP.NET Web API, Unit Testing, REST, LINQ, ASP.NET Core, Microsoft SQL Server, Scrum, Git, Object-oriented Programming (OOP), HTML, Azure, Microsoft Azure, SQL, .NET 6, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, REST APIs, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Jira, Markdown, Functional Programming, Object-oriented Design (OOD), SQL Server Management Studio, Refactoring, Design Patterns, Visual Studio Code (VS Code), Fiddler, Debugging, Mathematics, User Interface (UI), User Experience (UX), Front-end, Software Architecture, Web API, TypeScript, API Integration, Agile, Web Development, Full-stack Development, Node.js, Full-stack, GitHub, Solution Architecture, Angular, Windows Services, Entity Framework, Performance, Twilio, ASP.NET, IIS SQL Server, Back-end Architecture, Cloud Architecture, System Integration, SaaS, Web Applications, Object-relational Mapping (ORM), IdentityServer 4, .NET 7, Database Architecture, Cloud, React, Event-driven Architecture, Bootstrap

Senior Software Engineer

2017 - 2018

Shrader Group LLC

Designed and implemented an ETL pipeline to migrate a large amount of data from a legacy Drupal-based system to the new SQL Azure database.
Performed a codebase audit and fixed some serious issues related to security, database versioning, testability, and overall code quality.
Made a performance audit and improved the performance of critical APIs up to ten times.
Implemented continuous integration pipelines in VSTS.

Technologies: C#, .NET, Microsoft SQL Server, REST APIs, Entity Framework Core, ASP.NET Core, .NET Core, Data Integration, ETL, SQL Server Integration Services (SSIS), Microsoft Visual Studio, Unit Testing, REST, LINQ, Git, Object-oriented Programming (OOP), C#.NET, Azure, Microsoft Azure, SQL, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, CI/CD Pipelines, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Microsoft Data Transformation Services (now SSIS), Object-oriented Design (OOD), SQL Server Management Studio, Refactoring, Design Patterns, Visual Studio Code (VS Code), Fiddler, Debugging, Software Architecture, Web API, API Integration, Agile, Web Development, Full-stack Development, Full-stack, GitHub, Solution Architecture, DevOps, Entity Framework, Performance, IIS SQL Server, Back-end Architecture, Cloud Architecture, System Integration, SaaS, Web Applications, Object-relational Mapping (ORM), IdentityServer 4, Database Architecture, React, Data Mining

Senior Software Engineer

2016 - 2017

FRONTSTEPS

Implemented a centralized security token service and a granular permission-based authorization system for ASP.NET Core instead of coarse-grained role-based authorization.
Implemented an automated voicemail system with voice recognition so homeowners can register their visitors by phone, and community guards will be immediately notified about new guest invitations.
Built a notification API to deliver various notifications to the platform users.
Implemented a bunch of useful ASP.NET Core extensions and middleware, such as a distributed cache with fallback logic.
Worked on CI-related stuff, including continuous delivery pipelines and package management.
Worked on payment systems integration, back-end APIs, web and desktop clients, and more.

Technologies: C#, .NET, Microsoft SQL Server, SendGrid, PubNub, Twilio, Identity Server, OAuth, Microservices, REST APIs, Entity Framework Core, ASP.NET Core, .NET Core, Microsoft Visual Studio, ASP.NET Web API, Unit Testing, REST, LINQ, Scrum, JavaScript, Git, Twilio API, Object-oriented Programming (OOP), HTML, C#.NET, Azure, Microsoft Azure, SQL, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, CI/CD Pipelines, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Jira, Functional Programming, Object-oriented Design (OOD), SQL Server Management Studio, Refactoring, Design Patterns, Visual Studio Code (VS Code), Fiddler, Debugging, Redis, Software Architecture, Web API, API Integration, Agile, Web Development, Full-stack Development, Full-stack, GitHub, Solution Architecture, Angular, Windows Services, DevOps, Entity Framework, Performance, ASP.NET, Back-end Architecture, Cloud Architecture, System Integration, SaaS, Web Applications, Object-relational Mapping (ORM), Distributed Systems, IdentityServer 4, Database Architecture, Cloud, Event-driven Programming, Subscriptions, CSS, Event-driven Architecture, Bootstrap

Senior Software Engineer

2014 - 2016

Infor

Implemented an administration API with AWS integration for automatic code deployment.
Created an administration REST service and AngularJS-powered single-page web application on top of it.
Worked on new features, fixed bugs, and refactored legacy code.

Technologies: .NET, Moq, MSTest, Bootstrap, AngularJS, Windows Communication Framework (WCF), ASP.NET Identity, ASP.NET Web API, C#, Microsoft Visual Studio, Unit Testing, REST, LINQ, Microsoft SQL Server, Scrum, JavaScript, Object-oriented Programming (OOP), HTML, C#.NET, SQL, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, REST APIs, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Jira, Functional Programming, Object-oriented Design (OOD), SQL Server Management Studio, Refactoring, Design Patterns, Fiddler, Debugging, Front-end, Software Architecture, Web API, API Integration, Agile, Web Development, Full-stack Development, Full-stack, Windows Services, Entity Framework, Performance, ASP.NET, IIS SQL Server, Back-end Architecture, Cloud Architecture, System Integration, SaaS, Web Applications, Object-relational Mapping (ORM), Distributed Systems, Database Architecture, Cloud, Event-driven Programming, CSS, Event-driven Architecture

Software Engineer

2014 - 2014

Freelance

Implemented a web application for real-time server performance monitoring.
Created a chart control with the D3.js library and helped the client avoid using commercial charting libraries.
Implemented a REST API for one of the projects from scratch.
Implemented an efficient parallel data parser for MediaWiki API.

Technologies: C#, .NET, Moq, MSTest, Bootstrap, D3.js, AngularJS, ASP.NET Web API, SignalR, ASP.NET, ASP.NET MVC, Microsoft Visual Studio, Unit Testing, REST, LINQ, JavaScript, Object-oriented Programming (OOP), HTML, C#.NET, SQL, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, REST APIs, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Object-oriented Design (OOD), SQL Server Management Studio, Microsoft SQL Server, Refactoring, Design Patterns, Fiddler, Debugging, Software Architecture, Web API, API Integration, Agile, NoSQL, Web Development, Full-stack Development, Full-stack, Performance, Back-end Architecture, Cloud Architecture, Web Applications, Database Architecture, Data Structures, CSS

Senior Software Engineer

2013 - 2014

T-Systems International

Implemented new functionalities and business logic for desktop and web applications.
Helped integrate the software system with external services like SAP and others.
Provided on-site application support and helped resolve issues on the customer's site.
Helped to meet a bunch of important deadlines during the project's lifetime.
Made a presentation on code review and best practices applicable to it.

Technologies: .NET, ASP.NET MVC, Entity Framework, Windows Communication Framework (WCF), C#, Microsoft Visual Studio, Unit Testing, REST, LINQ, ASP.NET Web API, Microsoft SQL Server, Scrum, JavaScript, Object-oriented Programming (OOP), HTML, C#.NET, SQL, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, REST APIs, Architecture, SOLID Principles, Dependency Injection, Inversion of Control, Jira, Functional Programming, Object-oriented Design (OOD), SQL Server Management Studio, Refactoring, Design Patterns, Fiddler, Debugging, Front-end, Software Architecture, Web API, API Integration, Agile, Web Development, Full-stack Development, Full-stack, Windows Services, Performance, ASP.NET, IIS SQL Server, Back-end Architecture, Cloud Architecture, System Integration, Web Applications, Object-relational Mapping (ORM), Database Architecture, CSS

Software Engineer

2010 - 2013

ETNA Software

Designed and developed a bunch of core system components: back-end APIs, services, and libraries for the sogotrade.com trading platform.
Implemented and supported streaming and load balancing solutions for real-time market data delivery.
Integrated back-end components with the customer's service monitoring system.
Developed a market data provider with a web-based admin panel and AmiBroker integration.
Introduced unit testing practices and testable code concepts to the project.

Technologies: .NET, Moq, MSTest, NUnit, ASP.NET MVC, Microsoft SQL Server, Entity Framework, Windows Communication Framework (WCF), C#, Microsoft Visual Studio, Unit Testing, REST, LINQ, Scrum, JavaScript, Object-oriented Programming (OOP), HTML, C#.NET, Java, SQL, APIs, Source Code Review, Code Review, Task Analysis, Visual Studio, Back-end, SOLID Principles, Dependency Injection, Inversion of Control, Functional Programming, Object-oriented Design (OOD), SQL Server Management Studio, Refactoring, Design Patterns, Debugging, Mathematics, User Interface (UI), User Experience (UX), Front-end, MySQL, REST APIs, Web API, API Integration, Agile, NoSQL, Web Development, Full-stack Development, Full-stack, Windows Services, Performance, ASP.NET, IIS SQL Server, Back-end Architecture, Cloud Architecture, System Integration, SaaS, Web Applications, Object-relational Mapping (ORM), Database Architecture, Data Structures, CSS, Event-driven Architecture, Data Mining

Experience

Boostlingo Platform

https://boostlingo.com

The Boostlingo platform unifies all the technology and workflow components necessary to support the management and coordination of customers interpretation related tasks, including on-site interpreter appointment scheduling, the management of on-demand and scheduled over-the-phone and video remote interpreting sessions, complete with all the ancillary business analytics and business administrative tools that customers need to get the job done.

Sogotrade.com Trading Platform

http://sogotrade.com/

Sogotrade is a large-scale distributed platform for stock and options trading. It includes web and desktop client terminals and a set of powerful market research tools to help customers achieve their investing and trading goals.

ETNA Trader

https://www.etnasoft.com/etna-trader/

ETNA Trader is a flagship all-in-one white label trading platform for online broker-dealers. It features a front office and back office and integrates with a variety of third-party services and exchanges.

ASPro

An enterprise software system for TÜV SÜD, a service corporation focusing on testing and certification in the industrial sector.

The system consists of two major parts: a desktop workstation for the technical inspection of cars and other vehicles and a web application for organizing drivers' license exams, surrounded by a set of back-end services and external systems.

Infor Learning Management System

Infor Learning Management System is an enterprise SaaS solution for creating, delivering, and reporting on learning throughout customers' internal and extended organization. The goal of this solution is to replace complex processes, workflows, and systems with sophisticated yet intuitive technology.

PolyGen

https://github.com/sergey-kolodiy/PolyGen

PolyGen is an open-source Roslyn-based code generator that produces an object-relational mapping layer using Entity Framework, REST API using ASP.NET Core Web API, and a user interface for a user-defined domain model.

Microsoft Certified Professional

https://mcp.microsoft.com/Anonymous/Transcript/Validate

Microsoft Certified Professional (MCP) certification validates IT professional and developer technical expertise through rigorous, industry-proven, and industry-recognized exams. MCP exams cover a wide range of Microsoft products, technologies, and solutions.

To validate the certification, use the following information:
Transcript ID: 1166968
Access Code: F4163941

Functional Programming Principles in Scala

https://www.coursera.org/verify/TN47UQ4G6A

The Functional Programming Principles in Scala course introduces the cornerstones of functional programming using the Scala programming language. In this course, students discover the elements of the functional programming style and learn how to apply them usefully in their daily programming tasks, such as modeling business domains or implementing business logic.

Stack Overflow — Top 7% Overall

http://stackoverflow.com/users/3478087

Stack Overflow is a place where developers and technologists go to gain and share knowledge.
Seventy-seven answers were given.
Active in C#, .NET, ASP.NET, ASP.NET Web API, Unit testing, and Entity Framework. Top 7% overall.

Publication

Unit Testing and Coding: Why Testable Code Matters

https://www.toptal.com/qa/how-to-write-testable-code-and-why-it-matters

Skills

Languages

Markdown, C#, JavaScript, C#.NET, T-SQL (Transact-SQL), HTML, SQL, TypeScript, Java, Scala, CSS

Frameworks

ASP.NET, .NET Core, ASP.NET Core, .NET, ASP.NET Web API, ASP.NET MVC, Angular, Entity Framework Core, Entity, NUnit, AngularJS, IdentityServer 4, Bootstrap, ASP.NET Identity, Windows Communication Framework (WCF), OAuth 2

Libraries/APIs

LINQ, Web API, React, Entity Framework, REST APIs, Moq, Node.js, SignalR, PubNub, SendGrid API, Twilio API, D3.js, Telegram Bot API

Tools

Visual Studio, Microsoft Visual Studio, GitHub, Azure DevOps Services, Git, Fiddler, Roslyn, Chrome Developer Tools, MSTest, SendGrid, Postman, Trello, Jira, Twilio Programmable Video, Zoom

Paradigms

REST, Unit Testing, Object-oriented Programming (OOP), Dependency Injection, Object-oriented Design (OOD), Inversion of Control, Event-driven Architecture, Refactoring, Scrum, Microservices Architecture, Microservices, Functional Programming, Metaprogramming, Design Patterns, Azure DevOps, Agile, DevOps, Back-end Architecture, Object-relational Mapping (ORM), Event-driven Programming, ETL, Test-driven Development (TDD), Agile Software Development

Platforms

Visual Studio Code (VS Code), Azure, Twilio, Windows, Arduino, Web

Storage

Microsoft SQL Server, SQL Server Management Studio, Redis, NoSQL, IIS SQL Server, Database Architecture, Data Integration, SQL Server Integration Services (SSIS), MySQL

Other

SOLID Principles, .NET 6, APIs, Task Analysis, Back-end, Debugging, Web Development, Full-stack Development, Full-stack, Solution Architecture, .NET 7, Code Auditing, Single-page Applications (SPA), Identity Server, Algorithmic Trading, Microsoft Azure, Source Code Review, Code Review, CI/CD Pipelines, Architecture, Mathematics, Software Architecture, Max for Live, API Integration, Windows Services, Performance, Cloud Architecture, System Integration, SaaS, Web Applications, Distributed Systems, Data Structures, Cloud, Subscriptions, Data Mining, OAuth, Performance Analysis, Microsoft Data Transformation Services (now SSIS), Domain-driven Design (DDD), Trading, Stock Price Analysis, User Interface (UI), User Experience (UX), Front-end

Education

2005 - 2010

Bachelor's Degree in Information Systems and Technologies

Voronezh Institute of High Technologies - Voronezh, Russia

Certifications

SEPTEMBER 2015 - PRESENT

Microsoft Certified Professional

Microsoft

SEPTEMBER 2015 - PRESENT

Microsoft Specialist: Programming in C#

Microsoft

JULY 2014 - PRESENT

Functional Programming Principles in Scala

Coursera