Personal information

Name: Krzysztof (Kris) Kotlarek

Phone: +61 0490719318

City: Sydney - Australia

Visa: Skilled Independent Visa - Permanent Resident


Skype: kotlarek.krzysztof


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

I can help you 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.

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

  • Commenced as a single developer on the product and grew with the company to assume the role of team leader.
  • Developed and maintained B2B projects built on the government Employment Support Service system.
  • Demonstrated strong communication and issue management skills.
  • Met deadlines while handling highly confidential data.
  • As the right hand of the CTO, maintain deployments, build and systems configuration infrastructure of our products.
  • 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 the platform for digital education ( using technologies such as Ruby on Rails, PostgreSQL and Javascript.
  • Practiced TDD with RSpec.
  • Responsibilities include the integration of the chosen CMS into the existing platform.
  • Implemented a complete redesign of the client’s dashboard and built the 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.
  • I drove the business direction of the company and the development of tailor-made Rails applications.
  • I gained extensive experience implementing blog themes, Refinery CMS sites, e-commerce sites based on the Spree platform and implemented custom-built sites from scratch.
  • I developed a broad projects portfolio including:,,,,
  • I also configured and maintained multiple Linux-based servers (RVM, Passenger with REE, Apache and Postfix).
  • One of my most successful projects was a platform connecting commercial banks with credit offices based all over 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

Personal projects - founder

06.2016 - now

App to monitor mood and help people with anxiety, depression and other mood disorders. Built with Ruby on Rails, Angular2 and D3. In addition, delivered the mobile app 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 Rspec Git TDD Capistrano Nginx Unicorn Data Migration CasperJS Ionic2 D3


M.Sc. (Eng) Wrocław University of technology

2005 - 2010

Teleinformatics (with specialities in Teleinformatic Systems Planning)

Thesis - Security and performance analysis of selected web frameworks


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

Coursera, Edx and Future Learn

Courses and Certificates



Open Source

Author or Co-author

Bugfixes and improvements