Personal information

Name: Krzysztof Kotlarek

Phone: +61 0490719318

Country: Australia


Skype: kotlarek.krzysztof


I am a motivated and passionate Ruby on Rails developer, freelancer and entrepreneur currently living in Poland

I can help you to build a prototype of your next project, get your startup off the ground, or join your team and help you move forward with the speed of light.


M.Sc. (Eng) Wrocław University of technology

2005 - 2010

Teleinformatics (with speciality in Teleinformatic Systems Planning)

Thesis - Security and performance analysis of selected web frameworks

Work Experience

Jn Solutions - Remote Team leader and Ruby on Rails developer

02.2017 - now

Jn Solutions - Remote Ruby on Rails developer

09.2014 - 01.2017

Jn Solutions - Team leader and Senior Ruby on Rails developer

01.2014 - 08.2014

Jn Solutions - Senior Ruby on Rails developer

04.2013 - 12.2013

Jn Solutions - Ruby on Rails developer

01.2013 - 04.2013

Started as a single developer on product and grew with the company to the team leader. Developed and maintained B2B project built upon government Employment Support Service system. Demonstrated strong communication and issue management skills. Met deadlines while handing highly confidential data. As a right hand of CTO I helped maintain the deployment, build and systems configuration infrastructure. Improved product performance by built caching system based on sidekiq and redis.

Tutoria GmbH - developer

09.2011 - 12.2012

Evaluated programming code for efficiency, debugging and quality assurance of platform for digital education ( using technologies like Ruby on Rails, PostgreSQL, Javascript. Practiced Test-Driven Development with RSpec. Responsible for the integration of a Content Management System into the existing platform. Developed a complete redesign of client's dashboard and built premium service of Tutoria.

"Krzysztof is a great developer who is able to deliver web-apps in time and quality. Besides his technical skills and professional attitude, he is a great guy to work with."
Thomas Zeller, Director Product, Tutoria GmbH
"Krzysztof is a prolific Rails developer, able to provide complete solutions quickly and without sacrificing quality. He is also a very outgoing person, easy to communicate with and definitely a team player. I think he will be a linchpin of whatever project you find yourself working on."
Jarosław Rzeszótko, Software Developer, Tutoria GmbH

Useo - co-founder

01.2009 - 12.2011

I was one of the co-founders of a Ruby on Rails startup in Poland. Worked on the business direction I was also responsible for development of tailor-made Rails applications. I gained extensive experience implementing blog themes, Refinery CMS sites, e-commerce sites based on Spree platform, and custom-built sites from scratch. I managed to develop a broad projects portfolio including: euro-finanse,,,,,,,,, Configured and maintained multiple Linux-based servers (RVM, Passenger with REE, Apache, Postfix). One of my most successful project was a platform connecting commercial banks with credit offices based all around Poland.

"I have worked with Krzysztof on a number of projects, both small and large. I was impressed with his quality of work as well as the ability to keep strict deadlines. Krzysztof and his team are some of the best programmers I have had pleasure to work with."
Radek Kotlarek | SEO Expert, Technical Director, IEG Marketing

Freelance - founder

01.2005 - now

Appliction to monitor mood and help people with anxiety, depression and other mood disorders. Built with Ruby on Rails, Angular2 and D3. In addition, mobile application for android and ios was delivered with Ionic2.

Cyferki - developer

01.2007 - 12.2012 is an e-commerce platform based on Spree. Developed an extension for wholesale clients. One of the most progressive functions included currency converter based on daily currency rates.

"Krzysztof carried out the tasks assigned to him with self initiative and great care. We were very pleased with the results."
Krzysztof Maszkowski, Owner of Cyferki


Ruby Ruby on Rails XHTML CSS Bootstrap Javascript jQuery Angular2 CoffeeScript TypeScript SQL Redis Sidekiq Integration with OpenAM Integration with OpenStack Integration with Facebook Rspec Git Test driven development Capistrano Nginx Unicorn Data Migration CasperJS Ionic2 D3


  • Polish: Native
  • English: Fluent
  • German: Intermediate

Coursera, Edx and Future Learn

Courses and Certificates



Open Source

Author or Co-author

Bugfixes and improvements