Serhii – Ruby on Rails, Ruby, Redis

A global hotel chain and a group of private members' clubs. Membership is selective and members are drawn mainly from the media, arts, and fashion industries

• Developed and maintained microservices using Ruby and Grape framework.
• Implemented Apple Pay for the application used for payments in the company's restaurants, enabling faster transactions compared to the previous system that only accepted credit cards.
• Updated over 10 microservices to the latest Ruby version, resolving gem dependencies.
• Debugged and resolved application issues
• Utilized Kubernetes for container orchestration and management.
• Monitored and debugged applications using Kibana.
• Ensured comprehensive test coverage, enhancing service reliability and stability.

It is the employee rewards and recognition platform for the modern workplace. It enables companies to reward top employees with memorable, personal, and shareable experiences. Experiences as rewards not only provide a more meaningful avenue for employee recognition, but also create a lasting impact on your top engagement metrics (like increased employee motivation and retention rates, and providing a more positive company culture).

• Worked on experiential rewards & recognition platform as a Ruby on Rails developer.
• Worked with GraphQL to develop endpoints
• Developed Ruby on Rails microservice for an internal tool with Kafka(Karafka) integration.
• Worked on Rails library updates.
• Closed tech debts related to the code refactoring.
• Worked on performance optimizations for endpoints
• Got experience with dry.rb libraries such as dry-schema, dry-validation, dry-monads

It is a reseller shop software that handles the automated sending of invoices and offers payment methods. One of the biggest fin-tech platforms in the DACH region.

• Got experience with the Vue.js framework.
• Developed delivery feature for logisticians.
• Developed promo code feature from scratch.
• Developed upgrade/downgrade subscription feature with Stripe.
• Upgraded version of Stripe API integration for the whole project.
• Worked on performance optimizations related to database queries and also to the page speed up.
• Developed in short terms shop feature, that adds the possibility to create for users their own custom shops with custom domain.

It is the largest e-commerce project in Switzerland for creating car event presentations and concerts. Includes an admin panel for creating events, a custom checkout page, and a presentation page.

• Added tests(integration/unit) from scratch to the legacy e-commerce project, it gained test coverage to 90%.
• Made improvements that speed up admin panel pages using raw SQL queries and refactoring of existing ones.
• Refactored parts of codebase using service objects, presenters, query objects.
• Wrote service that generates excel files from a raw SQL query and gives nice statistics. This service was 5 times faster than the previous implementation.
• Implemented one master project for 15 projects that have different features inside like payment systems and creation of events.
• Upgraded rails from unstable beta version to version 4.2, upgraded ruby and gem dependencies.
• Solved database migrations for 15 projects that were combined in a single master project.
• Implemented from scratch Saferpay payment system for the master project. This helped to dropped the rails engine and one custom gem dependency.

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Internal project for collecting ticketing data from various resources and consolidating event data. As a company was an owner of the stadiums worldwide, they decided to create their internal service for creating events and concerts.

• Developed the project from scratch as a Full-stack developer
• Got experience with Ember JS framework.
• As a frontend developer I worked on implementing features and covering all pages with tests.
• Created custom queries for the backend as we used JSON API.
• Added custom error handler to the whole project with notifications.
• As a backend developer, I created the database schema, added CRUD for API.
• Developed services that used Sidekiq for activation/deactivation of old tickets.
• Covered the whole backend with the request, model, and unit tests.
• Added automation tests using WebdriverIO

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The project has real-time green compliance dashboards, instant verification of green building products, and the ability to track carbon and ESG metrics. It simplifies sustainability by providing solutions to make it easier for green construction projects to be built on time and on budget.

• Added query objects to optimize the query to a database.
• Speeded up pages that had complex queries with AJAX calls. Added tests.
• Refactored fat controllers with service objects.
• Worked mainly on performance optimization for the project.
• Added new features and maintained the whole project.
• Added tests to the existing functionality.