Krzysztof Stanisław Zielonka

Software Engineer

full-stack (backend focused)

Full-stack software engineer with 10+ years of experience, specializing in backend development for web and mobile applications. Proficient in JavaScript, TypeScript, Ruby, and Java, with strong expertise in TDD, OOP, DDD, CQRS, and Clean Architecture. Experienced with React, Docker, Terraform, AWS, and various databases (SQL, NoSQL, wide-column).

I’ve worked in both small and large companies, contributing to Agile teams (1–10 members) delivering scalable MVPs and products. Committed to clean, testable code following Beck’s Design Rules (tests, revel intention, no duplication, fewer elements). Open-minded and driven by new challenges.

📱 +48 600 056 671
📧 krzysztof@zielonka.dev
🏠 Wrocław, Poland
www.linkedin.com/in/krzysztof-stanislaw-zielonka/

Skills

TDD
OOP
DDD
CQRS
Modular Monolith
Clean Architecture
Hexagonal Architecture
SOLID
Java
TypeScript
JavaScript
Ruby
Nest.js
Ruby on Rails
React
AWS
Docker
Kubernetes
Terrafor
PostgreSQL
MongoDB
AWS DynamoDB
ElasticSearch

Experience

Grapes

Lead Software Engineer
(full-stack Node.js/TS/React)

Jun 2024 - Present (over 1 year)

An e-commerce platform for natural wines featuring an AI-powered wine scan functionality. This comprehensive project included Stripe payment integration, order processing, multiple React frontends, image processing via an integrated AI Python service, and Shopify integrations. The platform was built as a modular monolith with highly separated, well-tested modules designed in DDD event-sourced aggregates. I was involved in all phases of the project—initial setup, development, and delivery—working both independently and as part of a team of around 10 people.

Revolut

Senior Software Engineer
(backend Java/Node.js)

Mar 2023 - Apr 2024 (over 1 year)

I joined Revolut as a Senior Node.js Engineer and soon transitioned to working with Java. I was part of the POS (Point of Sale) team, developing a subproduct tailored for restaurants, covering modules such as orders, payments, reporting, product, and table management. I gained hands-on experience with event-driven architecture and a microservices ecosystem running on Google Cloud Platform, handling high traffic and large-scale data using PostgreSQL and MongoDB.

Droids on Roids

Senior Software Engineer
(Node.js/Ruby on Rails/React)

Dec 2014 - Mar 2023 (7 years)

At Droids, I worked on multiple projects using Ruby on Rails, Node.js, Nest.js, React, and other technologies. I focused on building maintainable apps following TDD, the modular-monolith architecture and DDD approach with event sourced models. I set up infrastructure on AWS using Elastic Beanstalk with Docker, DocumentDB, S3, OpenSearch, SQS, and Terraform, with CI/CD. I collaborated directly with clients and participated in discovery workshops using Event Storming and Domain Storytelling to define MVPs and project scope.

Software Project

Fullstack Software Engineer
(Ruby on Rails)

Jun 2011 - Dec 2015 (4 years)

My first role was as a Ruby on Rails developer, contributing to both backend development and frontend implementation using JavaScript and CoffeeScript. Working at a software house, I was involved in multiple projects and collaborated directly with a diverse range of clients.

Education

Wrocław University of Science and Technology

Safe and Efficient Cloud Computing Management

2014 - 2015

University of Wrocław

Master's Degree, Computer Science

2012 - 2013

University of Wrocław

Engineer's Degree, Computer Science

2008 - 2012