Oleksandr – Ruby on Rails, Ruby, PostgreSQL

This is a bank-as-a-service solution that allows the client to incorporate banking into their applications via SDK or API. It is widely used by crypto marketplaces like Binance, Coinbase, etc.

• Added a new way of identifying clients, using their selfies and signed documents;
• Eliminated a number of performance-critical bugs, as a result, identification services were able to handle 1.5 million registrations per month, with peaks of 2.5 million.

This is an online construction management system with more than 2 million users. The company has built 60+ instruments for managing construction projects - from documentation and finances to construction safety and quality. It is widely used in the US, Canada, and Australia by big developers to build bridges, skyscrapers, hotels, etc.

Oleksandr led the UI modernization team of 6 engineers, which migrated UI from Rails views to React.

His key responsibilities as Principal engineer were to organize teamwork and communication between the Ukrainian and US parts of the team. Had to take part in technical decisions and architecture design. The other part was the migration of 2500+ API endpoints to a new stable version with improved stability, consistency, and standardization.

Each team has built its part of API, so consistency becomes a real issue. Due to the number of endpoints, manual migration to a new major version would take more than a year. Oleksandr's team introduced 5 different tools for automated migration and made it 10 times faster.

US-based company wanted to build a social network, similar in many ways to Linkedin, but for their client from the construction industry with news feed, job board, chat, social feed, where clients can leave posts and comments. They had a small team of 2 engineers and one designer to build a POC application in less than 6 months. Procore liked it so much that they developed it for the next year, adding more features, improving reliability. Before being moved to the support department portal had approximately 300000 daily active users.

Oleksandr was responsible for all the back end, architecture, database engineering, and performance. He also did a lot of front-end development. He owned most of the features of the project and built most of them from start to finish. Oleksandr also proposed some experimental features like WebRTC-based video/audio chat.

This was a system that helped automate the evaluation of professional certification exams. It allowed the shortening of that period to 14 days and generated complicated statistics about the individual candidates, exam questions, etc.

Oleksandr was responsible for communication inside a team of 5 engineers, wrote tasks, did code reviews, took part in architecture discussions, and wrote the most complex parts of application logic.

A company selling its original GPS tracking devices. They started as a startup and required a web application integrated with Amazon for payment processing, Google Maps API, Facebook API, and Mandrill.

Oleksandr built integration with Amazon, mass email-based advertising system based on Mandrill templates, and map of used trackers based on Google Maps API and GPS data. As a result, the company has grown from 30 to 300 thousand customers over a year.