1. Decreased response time for each service by more than 20% by designing architecture, developing, deploying and maintaining a JWT library for microservice authentication.2. Reduced number of cron jobs by 7 times, decreased hardware usage during peak times (CPU by 25%, RAM by 5%) and reduced latency in peak times for end users by 10% by investigating cron job efficiency and optimizing cron job work.

* Decreasing page loads for all end-users by 30% by integrating a CDN. * Sped up content loading by 20% by analyzing and correcting indexes on PostgreSQL * Increased the number of end-users by 5% by designing, developing and implementing a lead generation tool with Ruby. * Introduced and implemented an anonymous user for approving iOS applications in Apple Store in Rails monolith application to allow clients to receive updates. * Increased delivery quality by optimizing and increasing the number of tests by 5% using RSpec.

* The affiliate marketing softwarehttps://quints.io/ * Unified the application and refactored Dockerfile and Docker-compose * decreased costs of developing by 40%. * Increased availability by 5% by adding a system for preventing DDoS attacks. * Introduced profiling tools for optimization of SQL requests * increased report generating by 5%.

* Mokka is an installment purchase service in Russia, Poland, Romania and Bulgaria with 12M+ clients.https://mokka.ru/ * Increased system availability for clients by 10% by developing a service-based application for clients. * Sped up API maintenance by 30% by combining disparate APIs. * Decreased the number of dishonest clients by 15% by refactoring and improved credit calculations. * Increased the number of clients by 15% by integrating a loan broker.

* Prevented a 20% loss in revenue by designing, architecturing, developing and implementing an application from scratch to meet new license requirements using mostly Ruby, Rails, Apache Kafka in three months. * Increased code quality by organizing code reviews. * Communicated with licensing regulator for clarification of the requirements to schedule achievable goals. * Completed project on time by estimating, managing and planning all team tasks. * Simplified the data handling process by collaborating with other teams to clarify the data formatting. * Improved code quality, and increased speed by conducting a Continuous Integration process.

* Increased company revenue by 10% by architecturing, developing and implementing an exchange currency feature from scratch for games in real-time. * Increased verified users by 3% by designing and implementing a caching layer with Redis for uploaded documents. * Decreased search time by 20% by modifying indexes in PostgreSQL. * Prepared, modernised and integrated the monolith application to the Kubernetes cluster; provided horizontal scalability and increased fault tolerance and availability. * Increased security of the application by adding a code linter and a security auto checker of third-party dependencies; prevented vulnerable versions of third-party libraries. * Interviewed 150+ candidates and selected top developers to double size of development team.