Oleg Gorbunov, Developer in Kiev, Ukraine
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Oleg Gorbunov

Verified Expert  in Engineering

Software Developer

Kiev, Ukraine
Toptal Member Since
July 4, 2018

Since 2011, Oleg has been working in full-stack web development along with maintaining a passion for quality programming. He has vast experience working with startups, developing applications from scratch, and working in small teams on remote work. He's committed to open source and fond of cutting-edge development


VarageSale (via Toptal)
Amazon Web Services (AWS), JavaScript, SQL, Microservices, Fluentd, Sidekiq...
WinOrLose (via Toptal)
JavaScript, Redux, Storage, Hosting, Authentication, Functions, Firebase...
Amazon Web Services (AWS), JavaScript, SQL, Ruby, AWS Elastic Beanstalk...




Preferred Environment

Sublime Text, MacOS

The most amazing...

...thing I've coded was made for my master's thesis—a program which can simulate competition interaction between large companies on international markets.

Work Experience

Full-stack Developer

2019 - 2019
VarageSale (via Toptal)
  • Reengineered an ads implementation.
  • Contributed to solving app bottlenecks in high-load areas.
  • Added new functionality for a member support microservice.
  • Migrated emails from Mailgun to SendGrid.
  • Made the app less coupled to the notifications microservice.
Technologies: Amazon Web Services (AWS), JavaScript, SQL, Microservices, Fluentd, Sidekiq, MySQL, Ruby on Rails (RoR), Ruby, React

Lead Developer

2018 - 2019
WinOrLose (via Toptal)
  • Supported the web-desktop, web-mobile, iOS, and Android platforms.
  • Built an MVP in two months.
  • Developed a sophisticated feed algorithm.
  • Implemented real-time updates, chat, payments, voting, commenting, filtering, an authorization flow, settings, and profile.
  • Created it all from scratch.
  • Worked on the full cycle of the build, deployment, and push to the Google Play and App Store.
Technologies: JavaScript, Redux, Storage, Hosting, Authentication, Functions, Firebase, Cordova, React

Chief Architect

2018 - 2018
  • Solved the n+1 issue which had acted as the server bottleneck.
  • Introduced caching for the Redux selectors.
  • Created an "auction progress" feature.
  • Worked remotely with a team spread across the US, Ukraine, Poland, Portugal; used GitHub, Slack, and Zoom.
  • Increased test coverage from 75% to 90%.
Technologies: Amazon Web Services (AWS), JavaScript, SQL, Ruby, AWS Elastic Beanstalk, Google Places API, Capybara, Stripe, Auth0, Firebase, Google Maps, Airbrake, Enzyme, Jest, Material UI, Redux-Saga, Redux, Webpack, MySQL, Ruby on Rails (RoR), React

Full-stack Developer

2016 - 2018
  • Developed the front-end of an admin tool app (React).
  • Implemented a Clubhouse-GitHub integration.
  • Consulted on the back-end of a GraphQL server's maintenance and set up.
  • Created a mechanism for universal email templates for SendGrid synchronization and customization.
Technologies: Amazon Web Services (AWS), JavaScript, SQL, Heroku, HockeyApp, Fastlane, Prismic, Google Places API, Scrum, SendGrid, Litmus, Surge Proxy Server, Mocha, Karma, Draft.js, Styled-components, Reselect, Redux Form, Redux-Saga, Redux, GraphQL, Apollo, Webpack, Node.js, React Native, React, TypeScript

Team Leader

2016 - 2017
  • Worked remotely with a team in the US; used Trello, Slack, and Skype to communicate.
  • Conducted code reviews for other developers.
  • Solved performance issues for the main page with a heavy functionality.
  • Created the architecture for the front-end of a web application with real-time updates.
Technologies: Amazon Web Services (AWS), JavaScript, SQL, Ruby, Amazon API Gateway, Heroku, Webpack, ECMAScript (ES6), Normalizr, React-Bootstrap, Redux-Saga, CSS, Redux, React, Capistrano, REST, PostgreSQL, Ruby on Rails (RoR)

Front-end Developer

2016 - 2016
A Job Board for Freelance Work
  • Implemented a freelancer onboarding flow.
  • Provided support for video interviews.
  • Implemented designs according to Material Design guidelines.
  • Developed Payoneer integrations and a massive payment management tool.
Technologies: Amazon Web Services (AWS), JavaScript, SQL, Redux, Heroku, Webpack, ECMAScript (ES6), Material UI, Redux Form, Redux-Saga, CSS, React

Senior Full-stack Developer

2015 - 2016
  • Upgraded the application from Rails 3 to Rails 4.
  • Designed and integrated an extensible ACL system with 100% coverage of endpoints on top of Pundit.
  • Successfully migrated to a SPA architecture.
  • Increased the readability and comprehensiveness of the application by 100% by cleaning up more than 100,000 lines of legacy code.
Technologies: JavaScript, SQL, Ruby, Cucumber, RSpec, Slack, Material UI, MySQL, Gulp, React, Polymer, Ruby on Rails (RoR)

Full-stack Developer

2013 - 2015
  • Worked as a semantic algorithms domain leader.
  • Increased the performance of a keyword tree generation 550 fold by inventing a new algorithm, optimizing SQL queries, and intensively using caching approach.
  • Successfully migrated a product from Padrino to Ruby on Rails 4.
  • Increased the collection rate from 500 to 50,000 keywords/hour by optimizing the database usage, using a Redis cache, improving the process flow, and separating concerns.
Technologies: Amazon Web Services (AWS), JavaScript, SQL, Ruby, RSpec, Sidekiq, Secure Automated Lending Technology (SALT), Elastic, MongoDB, Redis, PostgreSQL, Knockout (Knockout.js), Sinatra, Ruby on Rails (RoR)

Lead Developer

2012 - 2013
Cowries Bills
  • Set up an integration with the Stripe payment service.
  • Created multi-wallet support for international customers.
  • Implemented a background multi-process service to handle highly sensitive data.
Technologies: JavaScript, SQL, Ruby, Stripe, Payment Processing, Clickatell, Heroku, PostgreSQL, Ruby on Rails (RoR)

Full-stack Web Developer

2012 - 2013
  • Increased the performance from 100 to 400 requests/sec.
  • Developed an API protocol.
  • Implemented search, filter, sort, statistics, preview, and favorites modules.
Technologies: JavaScript, SQL, MySQL, Backbone.js, Ruby on Rails (RoR), Ruby

Full-stack Web Developer

2011 - 2012
  • Implemented calculation and management different leave types for employees in all countries, places, and time zones.
  • Worked as a reports domain owner.
  • Installed a state machine to handle the leaves states flow.
Technologies: JavaScript, SQL, jQuery, PostgreSQL, Ruby on Rails (RoR), Ruby


This is a mobile-bidding platform for auctioneers that allows you to engage bidders on their smartphones as well as your website. Imagine your bidders, downloading and using your app, to bid in your auctions. Simple to use for both you and your bidders.


Chairlift empowers your managers and employees with a robust solution to collect various types of real-time 360-degree feedback.

• Conduct a 360° evaluation of yourself
• Conduct a 360° evaluation of any employee you supervise
• Obtain feedback consistently throughout the year
• Keep track of your one-to-one meetings
• Exchange feedback on a group project
• Give or ask for feedback with your email software


WatchTower provides software that improves quality, transparency, and communication between brokers and carriers. We take the messy, complicated RFP process and simplify it down to a few steps, saving you from lost time and crispy hair. Say goodbye to the endless emails, disparate notes and edits, and disorganized spreadsheets of 1995, and say hello to a solution that lifts you into the cloud.


A private club for investors, philanthropists, and collectors to connect with their peers on a global scale. Members use Clade to share and advance their personal goals, both business and charitable. These objectives range broadly from launching new bespoke venture funds to promoting NGOs focused on maternal health in the developing world.

A Job Board for Freelance Work

I helped develop a global marketplace of prescreened, top freelance software engineers and digital designers. Our world-class engineers and designers have worked with some of the biggest technology companies in the world, including Google, Microsoft, Facebook, Apple, and many others. The site's clients include Fortune 500 companies such as PepsiCo and Pearson to famous venture-backed startups such as Gwyneth Paltrow's Goop.com.
2007 - 2013

Master's Degree in Economic Cybernetics

Tavrida National V.I. Vernadsky University - Simferopol, Ukraine


React Redux, Redux-Saga, Redux Form, React, Lodash, jQuery, Reselect, Clickatell, Sidekiq, Normalizr, Google Places API, Google Maps, Stripe, Backbone.js, Polymer, Stripe API, REST APIs, Node.js, SendGrid API


RSpec, GitHub, Git, Sublime Text 3, Chrome Developer Tools, Firebase Authentication, Sublime Text, Gulp, Capistrano, Airbrake, Auth0, Fluentd, Fastlane, Litmus, Mocha, Karma, SendGrid, Branch.io, Trello, Slack, Cucumber, Elastic, Jira, Webpack


Ruby on Rails (RoR), React Native, Redux, Jest, Material UI, React-Bootstrap, Draft.js, Capybara, Padrino, Sinatra, Knockout (Knockout.js)


Ruby, JavaScript, ECMAScript (ES6), TypeScript, GraphQL, SQL, CSS


REST, KISS, DRY, Hosting, Microservices, Kanban, Agile, Scrum, Object-oriented Programming (OOP), Database Design


Firebase, Amazon Web Services (AWS), MacOS, AWS Elastic Beanstalk, Heroku, HockeyApp, Amazon EC2


MySQL, PostgreSQL, MongoDB, Redis, Firebase Realtime Database, SQLite, NoSQL, Amazon S3 (AWS S3)


Firebase Hosting, Secure Automated Lending Technology (SALT), Amazon API Gateway, Apollo, Payment Processing, Enzyme, Functions, Authentication, Storage, Surge Proxy Server, Styled-components, Prismic, SOLID Principles, Cordova, Serverless

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