Christopher L. - Software Engineer

Warsaw, Poland

Experience

Apr 2024 - Present

1 year 9 months

Designed and implemented scalable Ruby on Rails microservices to handle 10,000+ concurrent users with 99.9% uptime.
Developed a cloud-based analytics dashboard integrating PostgreSQL and Redis, reducing data retrieval time by 35%.
Spearheaded front-end migration from legacy JS to React.js, enhancing application responsiveness and user retention.
Architected RESTful APIs with secure OAuth2 authentication, increasing integration efficiency with third-party services by 40%.
Implemented CI/CD pipelines using GitHub Actions, cutting deployment time by 50% and ensuring zero downtime releases.
Optimized SQL queries and indexes for high-volume transaction processing, improving database performance by 30%.
Led a team of 3 engineers in agile sprints, managing project backlog and delivering features ahead of deadlines.
Designed and executed unit and integration tests using RSpec and Capybara, achieving 95% code coverage.
Integrated AWS S3 storage for file uploads with automatic image optimization, reducing storage costs by 20%.
Developed feature toggle system allowing safe rollouts and A/B testing for critical product features.
Collaborated with UX/UI designers to revamp application interface, resulting in a 25% increase in user engagement.
Real-time Monitoring Platform: Built a Rails backend with WebSocket integration for live notifications and analytics.
Subscription Management System: End-to-end delivery of subscription billing, automated email alerts, and secure payment gateway integration.

Jun 2022 - Mar 2024

1 year 10 months

Developed full-stack web applications using Ruby on Rails and React.js, serving 50,000+ monthly active users.
Implemented PostgreSQL and Redis caching strategies, reducing page load times by 40%.
Built GraphQL API endpoints for efficient data fetching and front-end integration.
Deployed containerized applications on AWS EC2 with Docker, ensuring environment consistency across dev, staging, and production.
Automated deployment pipelines with Jenkins, reducing manual errors and accelerating release cycles.
Refactored legacy Rails codebase, improving maintainability and decreasing technical debt by 35%.
Designed and executed unit, integration, and E2E tests, achieving high reliability for production releases.
Integrated third-party APIs for payment processing, messaging, and geolocation services.
Collaborated with cross-functional teams to implement feature-rich e-commerce modules, increasing revenue by 18%.
Conducted performance profiling and implemented caching strategies, increasing application throughput by 50%.
Mentored junior developers, leading code reviews and knowledge-sharing sessions to promote best practices.
E-commerce Platform Revamp: Led full-stack redevelopment including Rails API, React front-end, and PostgreSQL integration.
Analytics & Reporting Module: Designed dynamic dashboards and reporting tools for stakeholders, enabling data-driven business decisions.

Apr 2019 - Dec 2021

2 years 9 months

Developed robust web applications using Ruby on Rails, React.js, and PostgreSQL, supporting enterprise clients.
Built modular front-end components and reusable UI libraries to enhance development efficiency.
Implemented RESTful APIs and integrated with internal and external systems.
Optimized database queries and designed indexing strategies, improving response times by 25%.
Collaborated with QA teams to implement automated testing frameworks using RSpec.
Maintained CI/CD pipelines for seamless code deployment.
Assisted in designing microservices for scalable backend architecture.
Refactored legacy applications, reducing maintenance costs and improving code readability.
Integrated third-party APIs for payment, geolocation, and email automation.
Participated in agile sprint planning and backlog refinement.
Inventory Management System: End-to-end delivery of real-time inventory tracking with reporting dashboards.
Client Portal: Developed secure Rails-based portal with multi-role access controls and API integrations.

Jan 2017 - Mar 2019

2 years 3 months

Assisted in developing full-stack applications with Ruby on Rails and JavaScript frameworks.
Created dynamic web pages and reusable front-end components using HTML, CSS, and jQuery.
Built and maintained RESTful APIs for internal and external integrations.
Optimized SQL queries for small-to-medium database applications.
Participated in code reviews and learned agile development practices.
Collaborated with senior developers to implement new modules and features.
Assisted in front-end UX improvements based on user feedback.