Sergei S Email and Phone Number

Participated in the open-source release of the BI system, resulting in a 30% increase in community contributions and a 15% reduction in internal development costs due to external collaboration. Collaborated with few cloud teams to implement integration with billing system, after that BI system has started making money.Set up ci/cd and terraform, github-actions, automated a lot of manual work for open source work.Enhanced frontend performance using code splitting and lazy loading, resulting in a 40% decrease in initial load time and a 20% increase in user engagement metrics.Developed a Backend-for-Frontend (BFF) service to streamline API calls for frontend applications, improving data fetching speed by 20% and enhancing overall performance.Improved database performance through indexing and query optimization, resulting in a 20% decrease in data retrieval times.

Designed and developed core features for services of a web app used by ~3M people daily.Developed domain auth, localization, using the best practices, and applying various web security practices.Developed a CI/CD pipeline that automated testing and deployment processes, reducing deployment time from hours to minutes.Implemented e2e tests on playwright and improved enterprise test coverage by 25%.Designed and integrated asynchronous APIs for high-traffic applications, ensuring non-blocking requests and improving user experience with faster load times by 15%.

Led a team of 5 engineers to develop an embedded music web player and music recommendation based on AI , improving user retention by 35%.Led a team in optimizing existing applications, achieving a 25% increase in overall performance and a 15% reduction in bounce rates.Developed a widget for detecting location by IP and collaborated with other teams for integration.Collaborated with DevOps to implement containerization using Docker, enhancing the scalability and reliability of applications in production.Utilized A/B testing methodologies to evaluate feature changes, resulting in a 35% increase in user retention.Mentored for new engineers and helped them to get started.

Developed and maintained fullstack applications using Node.js and React, achieving a 50% reduction in page load times.Participated in the migration of legacy systems to cloud infrastructure, reducing operational costs by 30%.Implemented responsive web designs using HTML5, CSS3, and JavaScript, enhancing user experience across devices.Optimized existing code and frameworks, reducing application size by 15% and increasing performance.

Architected and implemented backend services using PHP with the Yii2 framework, optimizing the codebase and reducing API response times by 30%. Designed RESTful APIs and improved database query efficiency, leading to a 25% reduction in data retrieval times and significantly improving the app's responsiveness.Built dynamic, responsive UI elements with JavaScript, React, and jQuery, enhancing user engagement and reducing bounce rates by 20%. Introduced code-splitting and lazy loading to minimize initial load time by 40%, resulting in improved user satisfaction and engagement metrics.Conducted performance profiling and refactored key components, reducing server load by 35% during peak usage hours and achieving a scalable architecture that accommodated a 50% increase in concurrent users without performance degradation.Established automated end-to-end testing and continuous integration workflows, reducing bug resolution time by 40% and deployment time by 60%, allowing faster iteration and stable production releases.