Przemysław Zalewski

Full Stack Web Developer from Wroclaw, Poland. My daily toolbox includes JavaScript, TypeScript, React, node.js, C#, and .NET.

I am fully committed to what I do, I am experienced with the full product lifecycle and I lead projects and teams to achieve their goals. I am product-focused, and I deliver. I love clean code, functional programming, and I participate in code reviews heavily. New challenges and opportunities are what I am looking for.

Currently working for Sandstream Development sp. z o.o.

Earliest availability from September 2025. Remote work preferred.

Phone

+48 884 828 647

Mail

[email protected]

Website

ciunkos.com

GitHub (work)

github.com/przemyslawzalewski

GitHub (personal)

github.com/Ciunkos

StackOverflow

stackoverflow.com/users/1384679

Contact me

Learn more

Education and work experience

In 2014 I have earned a Bachelor of Science degree in Computer Science at the Faculty of Computer Science and Management of Wroclaw University of Science and Technology.

Commercial work

July 2017 - present

Sandstream Development sp. z o.o. · Senior Full Stack Web Developer · JS, React, node.js, C#

2012 - July 2017

Self-employment · 25+ apps, 3 million+ downloads · C#, XAML, ASP.NET

September - October 2014

LOSO sp. z o.o. · RatingSpeed · Windows Phone app · C#, XAML

August - September 2014

IT4Biznes Marcin Hatalak · Fast-coffee · Windows Phone app · C#, XAML

February - March 2013

Cube Investments sp. z o.o. · Kwejk.pl · Windows Phone app · C#, XAML

August 2010 - January 2011, November - December 2012

Red Dot Games · I Am Rich The Game · Windows PC, Store app · C++, C#, DirectX

September - November 2009

Red Dot Games · Platformer game engine · Windows PC, Xbox 360 · C#, XNA

Job paths

Since 2017

Full Stack Web Developer · JavaScript

2012 - 2017

Windows App Developer · C#

Before 2012

Game Developer · C++, C#

Skills

Browse my skills to see if I can fit your project’s needs.

Tech

JavaScript
TypeScript
C#
React
node.js
Redux
React Native
HTML
CSS
Sass
styled-components
Jest
Express.js
Hapi.js
HTTP(S)
REST
WebSockets
JWT
Server-side rendering
Electron
Expo
npm
yarn
Webpack
Babel
Rollup
ESLint
Prettier
Chrome DevTools
Web security
puppeteer
nginx
MongoDB
Redis
WebGL
three.js
.NET
LINQ
Entity Framework
MS SQL

Tools and soft skills

Git
GitHub
GitLab
Jira
Confluence
Figma
Storybook
Docker
Docker Compose
CI/CD
Jenkins
GitHub Actions
AWS
Google Analytics
Cloudflare
Visual Studio Code
Visual Studio
Unit testing
Responsive design
End-to-end testing
Scrum
Scrum Master
Agile
Code review
Mentorship

Projects

There are some notable projects I have been working on recently.

Back Office Task Management System

June 2022 - August 2022

I joined the project with a vision to lead my team in the journey of delivering the most business value while maintaining the best quality of the code and systems. I supported transition into CI/CD/CD workflows. I brought a massively refreshed UI. The changes resulted in great user feedback and a continuous reduction of errors and time waste.

Client

PGS Software S.A. for undisclosed client

Technology

TypeScript, React, Next.js, node.js, Jest, WebdriverIO, Server-Sent Events, Web Extensions, MongoDB, styled-components, Tailwind CSS, CSS, REST, Auth0, Kubernetes, Datadog, Jira, CircleCI

My responsibilities

I was responsible for the technical leadership of a team of 4 developers while also performing active development of features. My day-to-day work included bringing improvements to existing systems and swift communication within the team and across the organization. Through active and deep code review participation, I encouraged my fellow team members to follow best practices and reduce technical debt. I led many fruitful discussions and technical meetings to align on common team values. I steered the development into a data-driven and short-feedback loop and maintained the backlog and sprint plans. I have undergone massive decoupling and simplification efforts to keep the repositories maintainable. By keeping a tight eye on security and correctness, I enforced strict auth, improved observability, and logging. I participated in the cloud cost reduction process by aligning the resource usage for deployments and optimizing for performance.

Ads and Ancillaries

Omio.com

July 2021 - May 2022

I worked closely with other developers, product managers, designers, and stakeholders to deliver the best ad experience and coverage across multiple touchpoints and platforms (web, mobile apps, email). I delivered new features while making huge improvements to existing code and processes. Even when my role was mainly on the frontend, I was always happy to jump in and get my hands dirty with server-side code or initially unfamiliar areas such as native code in mobile apps.

Client

PGS Software S.A. for Omio

Technology

TypeScript, React, JavaScript, node.js, React Native, Jest, Storybook, Hapi.js, REST, Redux, Swift, Kotlin, go, Java, Redash, SQL, BigQuery, Kibana, Grafana, Amplitude, Google Ad Manager, Firebase, Xcode, Android Studio, Jira, Confluence

My responsibilities

I was responsible for bringing the requested features to life, actively participating in the full life cycles from idea and design discussion to implementation, A/B testing, monitoring, and continuous improvement. I consistently got rid of technology debt, improved performance and kept services and features secure and up to date. I loved doing quick, deep, and helpful code reviews. I was always there when any help was needed. During this project, I actively participated in regular meetings and cross-team technical groups to share and disseminate knowledge. I maintained close collaboration with my colleagues during joint programming sessions in pairs and larger groups.

Undisclosed

July 2017 - June 2021

Web application for rendering, manipulation, and storage of 3D scans from profilometers, AFMs, and other 3D microscopes. A bespoke solution for a leading company that manufactures profilometry devices and is focused on thin-film measurements.

Client

Sandstream Development sp. z o.o. for undisclosed client

Technology

JavaScript, React, Redux, Redux Thunk, node.js, Jest, C#, .NET Core, Entity Framework, MySQL, ASP.NET Core, Sass, WebGL, three.js, Git, GitHub, Webpack, puppeteer, Expo, React Native, Storybook, APM (Azure Application Insights), AWS, Stripe

My responsibilities

I was responsible for full-stack software development using a React-based frontend with a C# backend to provide a web-based app that allows 3D image visualization and processing. During this project, I have learned how to work with an on-site and remote team to deliver a great product that satisfies client’s and users’ needs. I had gained experience with git workflow and collaboration with other developers. I had been performing code reviews and delivered high-quality code. I had also been responsible for the integration of external libraries and close cooperation with the APIs provider, which often resulted in a need for providing detailed bug reports and test cases. I’ve been continuously focused on providing great user experience, performance, and security, which is why I have brought in useful solutions like visual regression detection toolkit, secret leakage prevention, and optimized the build process to yield the optimal bundle and improve development experience.

Sandtime.io

January 2019 - present

In-house multiplatform SaaS time tracking system to improve workflows of creative people. With automatic time tracking and integrations, it makes all the parties involved in projects credible and accountable.

Client

Sandstream Development sp. z o.o.

Technology

JavaScript, React, node.js, Express.js, Sass, styled-components, Webpack, Docker, Docker Compose, nginx, MongoDB, mongoose, Redis, JWT, CI/CD, Jenkins, Git, GitLab, ELK Stack, puppeteer, Expo, React Native, Electron, Storybook, APM (Sentry.io), Amazon S3, paddle

My responsibilities

I was responsible for leading the project starting from creating the project vision, defining the microservices-based architecture powered by Docker containers, then by delivery of an MVP and continuous development of new features. During this project, I have also been performing a Scrum Master role and helped my teammates to deliver the desired product that meets users’ and stakeholders’ needs. I was responsible for setting up continuous integration, delivery, and deployment to shorten iteration and delivery cycles. I have introduced an end-to-end testing solution to maintain high quality and reduce risks of broken deployments. I have managed to get the app to multiple platforms and app stores (Windows, macOS, Linux, Windows Store, Mac App Store, Chrome Extension, Android, iOS) by using cross-platform tools like Electron and React Native. I was responsible for the external payment system integration and setting up a subscription model.

Validator

November 2019 - December 2019

Mobile app to help users capture perfect photos for ID documents. The app was submitted to the Polish government competition, GovTech, and scored 5th place.

Client

Sandstream Development sp. z o.o.

Technology

JavaScript, React, TensorFlow, TensorFlow Lite, face-api.js, OpenCV, WebAssembly, Android, Kotlin, Git, GitLab

My responsibilities

I was responsible for leading a small team to deliver a fully functional app that meets the competition’s requirements within a tight deadline. I have incorporated AI-based solutions and libraries to tackle the problem with near-real-time performance in mind. I have integrated React-based frontend with native Kotlin-based Android app that ran bare-metal models for extended performance on mobile, while still being able to run the app entirely on the web, fully offline. I have implemented a complex image detection and processing pipeline using face-api.js, OpenCV, TensorFlow, and custom functions. To achieve proper results, I have provided an extensive test suite, debug and visualization tools, and gathered a huge set of samples. Finally, I wrote a submission paper with a detailed report and documentation.

std

sandstreamdev.github.io/std

October 2019 - August 2020

Modern library of statically-typed modular functions for daily use in JavaScript and TypeScript projects. It served as a place to sharpen my TypeScript skills. Extensively used across the company’s projects.

Client

Sandstream Development sp. z o.o.

Technology

TypeScript, JavaScript, Rollup, Static site generators, Git, GitHub, GitHub Pages, GitHub Actions, React, node.js, Babel, Prettier, ESLint

My responsibilities

I was responsible for providing a library to reduce code duplication across the company’s repositories. I have defined module boundaries and extracted a huge chunk of utility functions to be strongly typed and included within the library. I wrote hundreds of TypeScript functions and I have covered them with tests to attain full coverage. I have been responsible for the package releases on npm and related chores. I have been performing code reviews to make sure the shared code is of high quality. With the custom static site generation toolkit, I have provided searchable and interactive documentation.

Korona Krulów

koronakrulow.pl

A game about COVID-19, polish government, and propaganda.

Technology

JavaScript, React, node.js, nginx

My responsibilities

I created and deployed a React-based game played by hundreds of thousands of people. I have managed to publish the game within two weeks of work. The game included over 400 actions and their effects that impact the internal simulation of infections and economy and society. I have implemented a leaderboards system to make the game more competitive.

Driving licence tests

testyprawojazdy.com

Responsive web app to prepare for the polish driving theory test exam.

Technology

JavaScript, React, node.js, Babel, ESLint, Visual Studio Code, MobX

My responsibilities

Writing the front-end with React.js, styling with CSS, designing responsive, mobile-friendly views

Database design and implementation of static data as a code modules system

Open-sourcing test questions and explanations along with an edit system based on Git

Implementing reactive view model using MobX and performance testing

Enabling server-side rendering using node.js on IIS with iis-node

Promegle

promegle.com

Anonymous chat application for Windows Phone and web.

Technology

C#, JavaScript, React, node.js, Babel, Redux, WebSockets, Docker, ASP.NET, Windows Phone, Windows Store

My responsibilities

Writing the front-end with React.js, Redux, and a custom styling solution

Implementing message queue system and reactive immutable database solution

Implementing video calling over WebRTC along with the signaling server

Automatic image classification using Yahoo’s Not Safe For Work deep neural model running on Docker

Integrating with legacy ASP.NET long polling back-end servers and C# code

Personal web page and blog

ciunkos.com

A static site with a personal blog and resume.

Technology

JavaScript, React, node.js, Babel, ESLint, Git, GitHub, Visual Studio Code, Webpack

My responsibilities

Writing the front-end with React.js, styling with CSS, using data as a code modules

Designing responsive and printable resume page

Static blog generation and integrating Disqus commenting system

Controlling source code and data versions using Git

Deploying server-side rendering with express.js with iss-node on Windows IIS

Store ᴾᴿᴼ

storeproapp.com

A Windows Phone application with redesigned and rethought store interface.

Technology

C#, XAML, MVVM, ASP.NET, MS SQL, Visual Studio

My responsibilities

Design and development of Windows Phone 8 application using C#, XAML, and MVVM pattern

Creating and deploying ASP.NET based web service and API endpoints along with a landing page

Designing and managing MS SQL database and integrating it with back-end service using Entity Framework

Back-end crawling services for deals discovery and sending push notifications

Internationalization implementation for over 192 languages

Deployment of multiple updates, maintenance work, and customer support

MusicTube

musictube.fm

Windows Phone, Windows Store, Web App for music videos playback from YouTube.

Technology

C#, XAML, MVVM, ASP.NET, MS SQL, Visual Studio

My responsibilities

YouTube and Last.fm APIs integration

Windows Store, Windows Phone and web app development using C#, XAML, MVVM, ASP.NET

Design and management of MS SQL database along with crawling services

Monetization through multiple ad networks

Implementation of multi-platform shared code solution

Deploying multiple updates, maintenance work and customer support

Pogaduszki

Windows Phone messenger application of Gadu-Gadu protocol.

Technology

C#, XAML, MVVM, ASP.NET, MS SQL, Visual Studio

My responsibilities

Development of native Windows Phone

Implementation of Gadu-Gadu binary protocol

Setting up a persistent proxy and push notification server

Deploying multiple updates, maintenance work, and customer support

APKA.TV

A streaming app of Polish public TV channels for the final studies project. Made in collaboration with Grzegorz Ślązak, Justyna Witkowska and Paweł Skiba.

Technology

C#, XAML, MVVM, ASP.NET, MS SQL, Visual Studio

My responsibilities

Collaborative development of native Windows Store and Windows Phone applications

Deployment of ASP.NET based streaming services and API endpoints

Development of streaming protocol with various bitrates

Designing chunked stream format which allows history playback

Deploying streamer app along with hardware wiring and antennas using DVB-T adapters

Kwejk.pl

Kwejk.pl feed viewer application for Windows Phone.

Client

Cube Investments sp. z o.o.

Technology

C#, XAML, MVVM, ASP.NET, REST

My responsibilities

Development of Windows Phone application based on client’s provided project using XAML, MVVM, and C#

Integration with existing web APIs

Collaboration with the project owner and the rest of the team

Monetization through different ad networks

Deploying multiple updates after the release

RatingSpeed

Network speed measurement app for Windows Phone.

Client

LOSO sp. z o.o.

Technology

C#, XAML, MVVM, ASP.NET, REST

My responsibilities

Development of Windows Phone application using XAML, MVVM, and C#

Implementing network speed measurement, test results statistics, and upload

Implementing the design provided by the client

Preparing the app for publishing in the Windows Store and providing app updates

Fast-coffee

Windows Phone dating app.

Client

IT4Biznes Marcin Hatalak

Technology

C#, XAML, MVVM, ASP.NET, socket.io, Visual Studio

My responsibilities

Implementing real-time chatting with socket.io

Implementing chat list, chat and profile views

Integrating with provided APIs

Working closely with the development team

I Am Rich The Game

Windows PC and Windows Store turn-based simulation game.

Client

Red Dot Games

Technology

C++, XAML, C#, DirectX 9, DirectX 11, Visual Studio

My responsibilities

Development of native Win32 game in C++ with a DirectX renderer

Networking protocol with Winsock, supporting up to four players

Implementation of provided game design and assets

Porting to Windows Store as hybrid native and C# app

Deploying to the app store and providing updates

Platformer game engine

Windows PC and Xbox 360 platformer game engine with a built-in editor.

Client

Red Dot Games

Technology

C#, DirectX 9, XNA, Visual Studio

My responsibilities

Development of XNA game engine

Creation of game editor with support for live play

Implementation of various game mechanics

Your next project can be here

Interests and future goals

I am always ready to learn new things and explore new opportunities.

My interests

Functional programming
Language design
Deep neural networks
UX
App development
DX
Security
Performance
User interface design
Dogs 🐶

Functional programming, language design, deep neural networks, UX, app development, DX, security, performance, user interface design, dogs 🐶.

My goals

Set up a Kubernetes cluster
Learn Haskell well
Give a speech about programming
Join a team of highly-skilled and experienced people
Improve my spoken English
Sharpen my TypeScript skills
Contribute to an open source project
Write more tests and explore TDD approach
Increase presence on StackOverflow

Set up a Kubernetes cluster.

Wyrażam zgodę na przetwarzanie moich danych osobowych dla potrzeb niezbędnych do realizacji procesu rekrutacji (zgodnie z Ustawą z dnia 29.08.1997 roku o Ochronie Danych Osobowych; tekst jednolity: Dz. U. 2016 r. poz. 922).

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