Waldek is available for hire

Waldek Jarosik

Verified Expert in Engineering

Software Architecture Developer

Wrocław, Poland

Toptal member since January 28, 2016

Expertise

Full-stack Algorithms Database SQL Linux Agile Development JavaScript PHP Python Django MySQL Git Express.js Node.js

Bio

Waldemar is an experienced software developer and project manager. He loves to lead people, but also to sit next to the monitor and code by himself. While building software, Waldemar likes a problem-solution approach that gives flexibility in choosing the right technology or programming language.

Portfolio

Mousetrap Games

Linux, Unity, Node.js, Java, C#, iOS, Android

LinkBook

SQLite, Android, Java

Opera Software

JNI, Android, Python, Java, C++, C

Experience

Software Architecture - 10 years
Full-stack - 7 years
Databases - 7 years
Technical Leadership - 6 years
Object-oriented Programming (OOP) - 6 years
Agile Software Development - 5 years
Scalability - 5 years
Security - 5 years

Availability

Part-time

Preferred Environment

Vim Text Editor, PyCharm, WebStorm, Git

The most amazing...

...thing I've created is a CAPTCHA breaking method based on a min-cost perfect matching algorithm (master's thesis).

Work Experience

Technical Leader, Software Architect

2017 - 2019

Mousetrap Games

Recruited and built the entire team of developers.
Managed agile processes.
Designed and code reviewed developers' solutions.
Designed and lead a couple of mobile applications in client-server based architecture.
Designed and lead a video game development, created in Unity.
Developed the most complicated features and prototypes of design solutions.

Technologies: Linux, Unity, Node.js, Java, C#, iOS, Android

Software Architect, Team Leader

2015 - 2017

LinkBook

Created the architecture of the main product, an Android application.
Managed a team of developers working on the project.
Coded the UI and back-end part of the application.
Helped the client in creating specifications of the product.
Tested the product on different devices.

Technologies: SQLite, Android, Java

Software Engineer, Team Manager

2014 - 2015

Opera Software

Maintained Opera Mobile/Mini for Android applications using C++ and Java.
Fixed bugs related to Chromium library.
Created branded versions of Opera for Android and modifications of user interface.
Attended BlinkOn, a conference related to the future of web browsers.
Managed Android developers team, line, and project management.

Technologies: JNI, Android, Python, Java, C++, C

Software Architect/Project Manager

2013 - 2015

Primagia

Created back-end and front-end architecture.
Managed a project team and coached CS students.
Coded and deployed the first version alone, from Linux server configuration, through back-end to front-end.
Integrated payments and invoicing systems through their API.
Configured the production server with backups, cron jobs, and automatic tests.
Maintained the server and application, fixing every critical problem.

Technologies: PostgreSQL, AngularJS, jQuery, JavaScript, Django, Python

Full-stack Developer

2009 - 2012

Nasza Klasa (nk.pl)

Created a standalone network communicator: C++, Qt, SQLite, XMPP, RPC.
Created user groups and social events feature serving millions of users online: PHP, JavaScript, MySQL, Memcache, Redis.
Created an online payments system: PHP, JS, MySQL.
Hunted CS students by giving lectures and testing them with a self-created set of problems.
Managed projects as a Scrum Master in an Agile way.

Technologies: Redis, Memcached, SQLite, MySQL, C++, JavaScript, PHP

Experience

Placeholders.java

A code I wrote, which contains two approaches to extracting coordinates of bounding boxes of transparent, connected shapes in big images. It was used in my startup Primagia, where we combine photos and allow users to upload images into placeholders.

Both approaches work in O(img_width*img_height) time. The first approach is a standard BFS algorithm implementing a simple flood-fill concept. Its disadvantage is the worst-case scenario, where a queue can consume up to O(img_width*img_height) memory. The second approach is a self-invented sweep algorithm, which only analyzes two consecutive lines. This gives O(img_width) the worst memory usage.

Primagia

Self-designed web shop cloud for people who want to sell their graphic designs as printings on different gadgets (e.g., cups, t-shirts).

Opera Mobile

http://www.opera.com/pl/mobile

I was supporting development of Opera Mobile and Mini for Android, serving tens of millions of users.

Social network portal

http://nk.pl

I've been working on many different features in Polish social network web portal serving millions of users online.

Run the Beat

Rhythmic video game built in Unity with a client-server based architecture for user data storage.

Education

2005 - 2010

Master's Degree in Computer Science

University of Wroclaw - Poland

Skills

Libraries/APIs

React, Node.js, jQuery

Tools

Eclipse IDE, Git, Android Studio, WebStorm, Vim Text Editor, PyCharm

Paradigms

Management, REST, Clean Code, Scrum, Agile Software Development, Object-oriented Programming (OOP), DevOps

Storage

Databases, Redis, SQLite, MySQL, Memcached, PostgreSQL

Languages

PHP, SQL, Python, JavaScript, Java, C#, C++, Bash, HTML, C

Frameworks

Django, Unity, Express.js, JNI, Qt, AngularJS

Platforms

Android, Linux, iOS, Windows

Other

Full-stack, Software Architecture, Scalability, Data Structures, Algorithms, Leadership, Technical Leadership, Security, HTTP, Design, Code Architecture, Servers

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