2N - Marcin Dziewiński - Ruby Developer

Experience

Projects & experience

2022-07 – 2022-10

Web application designed for children's association sharing their culture.

Technologies

Ruby on Rails Javascript Haml SCSS

Responsibilities

Made tons of both backend and visual amendments to make application more optimized, eye friendly and bug free
Created lots of unit tests with RSpec and E2E tests with Cypress

2022-10 – 2023-05

Web application for martial art trainers and students.

Technologies

Ruby on Rails Javascript Haml SCSS JQuery Bootstrap PostgreSQL

Responsibilities

Created events system with: registration forms for both registered users and guests, events acceptance by grand masters, mark event participants after the event, contact form for instructor

2023-02 – present

Group of 6 projects joining online stores for retails and wholesale customers, warehouse and restaurants applications.

Technologies

Ruby on Rails Javascript Haml SCSS JQuery PostgreSQL Docker AWS Sidekiq Capybara

Responsibilities

Built an inventory management system with automated stock level tracking and real-time adjustments
Implemented barcode scanner integration to streamline and automate warehouse operations
Integrated direct image fetching from a CMS via REST API, reducing manual asset management overhead
Developed a real-time logging system to detect and alert on unexpected data changes
Automated report generation and delivery to Google Sheets, eliminating manual reporting workflows
Updated the application by refactoring code, optimizing database queries, and Sidekiq jobs, fixing N+1 issues, speeding up page loads, and reducing AWS resource usage
Maintained and continuously improved a full-stack system, delivering both backend and frontend enhancements

2025-03 – present

Web application that allows donating unwanted clothes to selected charities.

Technologies

Ruby on Rails Javascript Haml SCSS JQuery PostgreSQL AWS Sidekiq

Responsibilities

Designed and implemented a full-stack discount code system - from database schema and Rails model through REST API validation endpoint and service layer, to real-time price recalculation in the frontend with report and admin panel integration
Integrated Tpay payment gateway - handling webhook verification (JWS), payment lifecycle management, and automated expiration of unpaid transactions.
Developed complex campaign configuration system with custom courier limits, dynamic form fields, and date-aware donation weight recalculation logic
Rebuilt the donation wizard flow with multi-step form, per-bag pricing, and a fixed donation calendar rendering across user and admin views
Introduced a donation category system (books, children's clothes, mixed) with a dedicated pre-donation selection screen, category-specific form flows, and full report integration across three report types
Extended and maintained DPD courier API integration, implementing new delivery categories, custom business logic, and conditional validation rules across the full stack.
Maintaining whole system and making both backend and frontend adjustments