Julian Kowalczuk CV

Mindset

I've started my adventure with code at the age of 15. Designing simple websites and computer science olympiads were the a great kick to becoming a programming enthusiast. I went through many technologies and projects solving the biggest problems, which made me a self-sufficient fullstack developer. I care a lot about clean code and good project quality. That's why in my small software house Husaria Solutions I bet on my personal faster methodology than Agile, what gives some space to deliver applications on time. Projects there are implemented by a group of friendly developers using modern frameworks and libraries in real scenarios where time is key. My personal goal is to create and maintain high-performance and low-energy applications, which is not so difficult thanks to the present times.

Programming languages

JavaScript (up to ESNext)

TypeScript

SASS/LESS/CSS

Dart

C#

Rust

Solidity

SQL

Python

Groovy

Backend skills

NodeJS

NestJS

REST

Cloud (AWS, GCP, Azure)

.NET Core

.NET Framework

GraphQL

Kafka

GRPC (better than REST)

MongoDB

MSSQL

PostgreSQL

WebSocket

Frontend skills

React

NextJS

React-Query

Redux

Vite/Webpack/Rollup

CSS-in-JS solutions

GraphQL

SolidJS

Svelte (including SvelteKit)

CerebralJS

Jest

Vitest

Playwright

Gatsby

SEO (GTM, GA4, Lighthouse)

Cypress

Mobile skills

Flutter (with web support)

React Native

Xamarin

Cordova / PhoneGap

Other skills

Docker

Kubernetes

Linux (Arch, Debian, Ubuntu)

Windows

Github Actions

Agile Development

GIT

Jenkins

Professional experience

Husaria Solutions (I'm CEO) Remotely (2021 - now)
100% remotely software house
Projects:

Video streaming site SvelteKit, PostgreSQL
First offer we get was a bit uncommon because of client industry (porn), but I'm glad I decided to take it. Video streaming restrictions pushed me into nice reasearch about self-hosted solutions and crypto payment integration is nice to have in code base.
Browser automation tool NodeJS
Client needed solution to automate some inputs and clicks on website at specific hour. We created agent with Chrome preview to do these task for him.
Crypto IT offers SvelteKit, PostgreSQL, Solidity
To go deeply in Web3 world, we decided to start some internal project. I really like Metamask wallet usage simplicity, so we would like to create web portal with eazy website navigation and safe offer realization process.
... and more, mostly listed on company projects page

CRIF Remotely (2023)
Fullstack development
Projects:

Big data transformer NodeJS, Rust, React (NextJS)
In order to speed up the company's vital data processing systems, I rewrote the entire project from JavaScript to Rust and connected it to other projects using NAPI (NodeJS API). The final solution was able to speed up processing by up to three times compared to the previous version of the tool.
Crawler NodeJS
I rewrote the project from JavaScript to TypeScript using modern approaches to concurrent and reliable data processing. The final solution was to use the newest approach in NodeJS for multithreaded applications - worker threads.

Legends of Elysium Remotely (2022) https://legendsofelysium.io
Blockchain development
Projects:

Blockchain logic for game NodeJS, Svelte, Solidity
I was responsible for writing smartcontracts and integrating blockchain solutions with the classical backend. backend. Smartcontracts were oriented towards ERC20 and NFT tokens.
I also prepared the frontend as a test dashboard.

Nextrope Remotely (2022)
Blockchain development
Projects:

Social events app NodeJS (NestJS), Solidity
Still under NDA, so cannot provide more info. I was focused on preparing fresh backend solution in microservices architecture.

Acaisoft Remotely (2021)
Fullstack development
Projects:

CRM for properties NodeJS, React (NextJS)
Quite huge and complex project, all-in-one tool like. Since I'm still under NDA, I can just say, that it was great opportunity to evolve in E2E testing.
Social app NodeJS (NestJS)
Focused mostly on E2E testing. App containing many modules, where part of them connects with external services (both self-hosted and 3rd parties).

Applover Remotely (2021)
Mobile app development
Projects:

Social app Flutter
It was great opportunity to cooperate with programmer, which was true clean-code writer. He followed almost every rule coming from Clean Architecture book. I was creating app with him from stratch, one of best experience in this industry.

Hackshield.pl Remotely (2020 - 2022)
Fullstack development
Projects:

Hackshield.pl - anty-cheat for Minecraft game (many technologies, but cant list them)
Even I've never played in that, I went in this project because of interesting technologies stack. Game industry differs from anothers, I had to setup many self-hosted solutions (private Kubernetes cluster) and fight with network issues (like load-balancer or proxy configuration). I was never working under such preasure, but now while project is already in production, every day we get new users and now we have also new server named TheVoid.pl. I'm still in this project caring about backend health and I hope it will let people spend their free time without stress coming from cheaters behaviour.

USER.COM Remotely (2020)
Mobile app development
Projects:

Social video app selling products Flutter
Finally I found nice project to do from scratch. NDA does not allow me to provide more details yet, but mostly I was doing some video streaming features using native iOS/Android on lower level. Unfortunately I lost motivation to in this job, because of breaking one of key important rule of programming. Project idea was exciting, but I had to step out because of distinct ways of software development.

CRODU Remotely (2019-2020)
Mobile app development
Projects:

App about health care React Native, NodeJS, Kafka
App is used to collect some data about our health and make an appointments. I was mainly doing backend, it was startup project. It was great opportunity to learn about great tools (like Kafka, which is lighter and faster than popular RabbitMQ). I really liked atmosphere here, probably best company I was working with. I resigned to work on private project, but I hope they finished their project in good condition.

Gorilla Agency Remotely (2019)
Fixing and extending CRM system
Projects:

CRM system React
I had to fix some bugs in system and add new features, where the most challenging one was dynamic form customized to generate fields by internal types

Full Stack Developer Powel, Gdańsk (2018 - 2019)
Responsible for building React dashboards to manage metering devices
and architecting reusables components library
Projects:

Incidents management system React, CerebralJS (JS)
System collects events from external systems and present them in complex table structures allowing user to manage them. As fullstack developer I were mostly creating reusables components and forms on front side, on backend side I were integrating Swagger with our project.
Refactoring map app React, Esri (JS)
It's side project (for described above) presenting incidents on map and statistics on charts with actions redirecting to management system. I had to refactor almost all application created by intern to make it work.
Rewrite map app React, Esri, Leaflet (TypeScript)
At the end refactored map solution was not good enough (Esri client library had many limitations), so we had to rewrite it completly. I created myself new project using TypeScript and Leaflet library, what improved performance much thanks to multi-level normalization for points arrangement.

Freelancer (2014 - now)
Websites development and deployment in direct cooperation with clients. At the start I were doing simply static or WordPress websites. Then I dropped it and decided to work as contractor (what I actually do). I won't list websites here (nothing special, because I had poor experience while I were creating them).
Projects:

Photobooth app for Opener Festival event React (JS), Node.js, .NET Core
App were taking photos and sending them by email or SMS. It was huge challenge for me and my friend. We got this offer just few days before event. He was lead developer, so most of app I created by myself. Project wasn't so hard, but because of time restriction I felt like on hackathon during development process.
Internal CRM React (JS), Redux, Redux-Form
App for huge customer. They needed specific structure of forms and events system with custom set of rules firing actions manipulating form or app behaviour. I had to override redux-form logic and create really complex UI.
and 60+ more by 2024 created with React, NextJS, React Native, Flutter, Node.js and many other tools...

.NET Developer NDI, Sopot (2017)
Responsible for desktop applications development (WPF and Windows.Forms),
refactor web applications and SQL databases. I were the only person working on projects.
Projects:

Barcode printing app Windows.Forms
Inside company, every document had to be identified by special number (and barcode). App had to be universal enough to print them on different paper sheets and different printers.
Documents identifier and deliver Windows Service
Every document scanned inside company had to be read by OCR library and depending on barcode deliver to specific external system. That one were a bit tricky, because some scan files were corrupted sometimes or barcode weren't clear enough to read it.
Migration from PostgreSQL to MSSQL Java, PostgreSQL, MSSQL
It was time for huge refactor of internal CRM. Some queries were native written, anothers using pseudo ORM. It was really painful for me as developer and let me understand how key clean code is.

Junior Full Stack Developer Kleder, Gdynia (2016)
Responsible for building MVC Core applications with communication of AngularJS frontend,
creating mobile POC’s using the Xamarin, Cordova and OpenCV
Projects:

Crawler app WPF
For testing my skills purpose I had to write Crawler app parsing website content and digging deeply in links. Performance was important here, so I had to test plenty of libraries to find best solutions.
Management system .NET Framework, AngularJS, Bootstrap
MVC project to manage co-workers, settlements and products, connecting with external client's APIs with multilevel permission authentication. I were creating forms and settings panel on front side, on backend side routes necessary for my part of work.
Geolocalizer POC Xamarin
Simply geolocalizer app. I had to find best solution for accurate results even with building and create simply backend logging data about my location changes.
Marks recognizer Xamarin, OpenCV
One of our client was interested in game where people had to collect points in checkpoints. Accurate results but without battery drilling... For me as junior it was really tricky. OpenCV is powerful library, but I had many problems with its wrapper for Xamarin and spent a lot of time to callibrate settings well.

Languages

English (upper-intermediate)
Polish (native)

Hobby

Personal development
Software development
Robotics
Neurobiology
Cognitive science
Aquaponic

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