Marcin S.Private profile: Upwork shows its earnings only to signed-in members, so we check it every few weeks, not daily. MRR here is a rough estimate (Upwork's six-month earnings ÷ months active). Last read Nov 5, 2026.

I’m a Full Stack Developer with over 12 years of experience specializing in Ruby on Rails. I build websites, intranet systems, and online stores, delivering clean, maintainable, and well-tested code. I also modernize projects by upgrading Ruby and Rails versions, updating gems, and ensuring applications remain secure, performant, and scalable. What I bring to your project: - Refactoring and optimizing code, including SQL queries - Building responsive web interfaces for mobile and desktop - Improving website performance and SEO - Upgrading Ruby, Rails, and project dependencies - Developing well-tested applications - both monoliths and microservices - Integrating APIs and third-party services - Leveraging popular Ruby gems and tools for testing, deployment, and automation Tech stack: Backend: Ruby, Ruby on Rails, Sinatra, MySQL, PostgreSQL, MongoDB, Devise, Solr, ActiveAdmin, RefineryCMS, CanCanCan, Sidekiq, Delayed Job, RSpec, Capybara, Selenium, Cucumber, RabbitMQ, Nokogiri, CarrierWave, Avatax, JSON, YAML, Capistrano, Docker, Heroku, Sentry, CircleCI, and more. Frontend: JavaScript, TypeScript, CoffeeScript, Vue, Angular, jQuery, VueX, RxJS, Bootstrap, Lodash, Axios, HTML, HAML, CSS, SCSS. Why work with me: I’m careful, dependable, and experienced in remote work. I focus on creating solutions that fit your needs and help make your project successful! Let’s build something good together! Marcin