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Marcin Sklodowski
Verified Expert in Engineering
Ruby Developer
Gdańsk, Poland
Toptal member since December 24, 2013
Bio
Marcin is a code purist, hopelessly in love with Ruby. He is a passionate software engineer with over a decade of experience contributing to multiple projects of various types and sizes. Marcin is happy working with others, is addicted to Scrum, and emphasizes maintaining effective development practices.
Portfolio
Etison LLC
Ruby on Rails (RoR), Localization, Haml, i18n, REST APIs...
FL Fintech E Gmbh dba Clarke.de
Ruby, Ruby on Rails (RoR), TypeScript, Scrum, REST APIs...
BuildEmpire, Ltd.
Ember.js, Ruby on Rails (RoR), Ruby, REST APIs, MySQL, SQL, JavaScript, Stripe...
Experience
- Ruby on Rails (RoR) - 16 years
- Ruby - 16 years
- Performance Optimization - 15 years
- APIs - 10 years
- Domain-driven Design (DDD) - 9 years
- LLM Integration - 3 years
- Claude API - 2 years
- Agentic Coding - 2 years
Work Experience
RoR Developer
2021 - 2022
Etison LLC
- Joined ClickFunnels to aid in its international growth, focusing on integrating localization into the main Rails application and several React applications.
- Took on the role of a specialist engineer tasked with resolving payment-related issues and offering support to fellow developers in this domain—utilizing my background in payment integrations.
- Swiftly navigated through the extensive codebase, learned these technologies on the go, and successfully met the project deadline—despite being new to some of the technologies used there.
Technologies: Ruby on Rails (RoR), Localization, Haml, i18n, REST APIs, Amazon Web Services (AWS), MySQL, SQL, JavaScript, Stripe, API Integration, PostgreSQL, React
Senior Ruby Developer
2018 - 2020
FL Fintech E Gmbh dba Clarke.de
- Brought on board initially to upgrade the main framework version of a challenging application. Met the deadlines, which led to my inclusion in the product and tech team of over 50 developers.
- Joined the architecture team, contributed to decision-making, developed solutions, led scrum meetings, and coordinated task breakdowns with PMs and designers.
- Identified and implemented strategies to eliminate dependencies on legacy code, enabling us to seamlessly introduce new functionalities.
Technologies: Ruby, Ruby on Rails (RoR), TypeScript, Scrum, REST APIs, Amazon Web Services (AWS), MySQL, SQL, Stripe, API Integration, PostgreSQL, Architecture, Fintech, Technical Leadership
Software Developer
2014 - 2017
BuildEmpire, Ltd.
- Developed a class booking system, including student profiles and a course search feature.
- Implemented a custom login service daemon that allows Rails application users to log into the FTP server.
- Helped build the Clarus Warehouse Management System (Claruswms.co.uk) from scratch to active use.
- Extracted reusable components from the codebase to external gems.
Technologies: Ember.js, Ruby on Rails (RoR), Ruby, REST APIs, MySQL, SQL, JavaScript, Stripe, API Integration, PostgreSQL, GraphQL
Software Engineer
2013 - 2014
Tix.nl
- Developed a Ruby on Rails application with a back-end written in Java
- Created integration tests with Capybara covering new functionalities.
- Performed TDD with RSpec and Cucumber.
- Actively participated in adapting the company's Scrum philosophy.
- Implemented a fully automated continuous integration process.
- Handled back-end and front-end performance benchmarking and optimization.
Technologies: Ruby on Rails (RoR), JRuby, REST APIs, Full-stack Development, MySQL, SQL
Software Engineer
2012 - 2013
Groupe SII
- Developed custom Redmine extensions and improved functionalities.
- Created a Symfony-based eCommerce project for one of the biggest Polish price comparison sites.
- Worked with an internal SOAP API.
- Tested code with PHPUnit and RSpec.
Technologies: Ruby on Rails (RoR), REST APIs, PHP, Full-stack Development
Back-end Developer
2011 - 2012
GoldenLine Sp. z o.o.
- Implemented new functionalities for the company's site, such as new client profiles.
- Optimized performance using Memcached, Membase, and the Sphinx Search Server.
- Tested using PHPUnit and Selenium.
- Created an internal API with the Silex framework.
- Improved core site functionality, including a candidate search engine for recruiters.
Technologies: Silex, PHP, Full-stack Development
Software Developer
2008 - 2011
Freelance
- Developed websites with PHP and Rails.
- Designed and developed various CRM applications.
- Audited and improved the performance and security of various websites.
Technologies: Ruby on Rails (RoR), PHP, Minimum Viable Product (MVP), Architecture, ChatGPT, Claude, Claude Code, Twilio, Artificial Intelligence (AI), Large Language Models (LLMs), Fintech, Mobile Apps, Technical Leadership
Project History
Shopping Cart - Purchasing Platform for Nokaut.pl
From day one, I swiftly contributed to a team effort, creating a unified payment system for Nokaut.pl. This offers customers a single platform to choose from various stores, enhancing their shopping experience.
New API for Customer Portal Rebranding and Back-end Scaling
As a part of the Digitalkasten team, I took a crucial role in rebranding the customer's portal by providing a reliable, secure, and fast API. Using the great testing tools that the Ruby world offers, we were able to introduce brand new features quickly without compromising customers' comfort and with full confidence that every part of the application works. This project's other essential purpose was to scale it up to the point where even a considerable amount of users and processed documents don't slow the application down. We achieved it by simplifying processes, optimizing the code whenever possible, and moving from ActiveRecord to plain SQL in key functionalities.
Skills
Libraries/APIs
REST APIs, Stripe, Claude API, React
Tools
RSpec, ChatGPT, Claude, Claude Code, Git
Languages
Ruby, SQL, JRuby, ECMAScript (ES6), Haml, TypeScript, PHP, JavaScript, GraphQL
Frameworks
Ruby on Rails (RoR), Ember.js
Paradigms
Test-driven Development (TDD), Scrum
Storage
PostgreSQL, MySQL
Platforms
OS X, Amazon Web Services (AWS), Twilio
Other
APIs, Software Design, Back-end, SOLID Principles, Performance Optimization, Domain-driven Design (DDD), API Integration, Minimum Viable Product (MVP), Fintech, Agentic Coding, LLM Integration, Architecture, Large Language Models (LLMs), Mobile Apps, Technical Leadership, Scalability, Localization, i18n, Full-stack Development, Artificial Intelligence (AI)
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