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Karol B., Software Developer in Artigas Base, Antarctica
Karol B.

Software Developer in Artigas Base, Antarctica

Member since January 8, 2014
Karol is always seeking new challenges in his life and technology, and enjoys building things from the bottom up. Whenever he's put on an existing project, he tries to bring in new air whenever possible. His favorite project will always be the one he's currently working on.
Karol is now available for hire


  • Freelance
    Ruby on Rails, JRuby, TorqueBox, Trinidad, PostgreSQL, MySQL, Resque
  • Enrian
    Ruby on Rails, Tomcat, JRuby, Logstash, CircleCI, Apache JMeter, Splunk
  • JetMinds
    REST, Rails, JRuby, Trinidad, jQuery, Facebook Platform, J2ME, LWUIT, MySQL...
Artigas Base, Antarctica



Preferred Environment

Linux, Git

The most amazing...

...thing I've built and supported is the backbone of JRuby (on Rails) deployments.


  • Consultant

    2011 - PRESENT
    • Helped a client resolve a concurrency issue on a high-load database connection.
    • Provided on-site support for an application, expecting thousands of req/sec deployed to Heroku.
    • Configured and fixed an application's ability to run with zero downtime deploys.
    • Converted an outdated massive code base to an up-to-date Rails version (from 2.3).
    • Resolved an issue in a TorqueBox/JBoss cluster for a client in staging, and offered advice for improving Server configuration.
    Technologies: Ruby on Rails, JRuby, TorqueBox, Trinidad, PostgreSQL, MySQL, Resque
  • Technical Support Engineer

    2016 - 2018
    • Started as a technical (support) expert for the team, dealing with production issues in one of Europe's biggest banks. This later also turned into implementing new features for the lending platform apps and pushing the technological stack for better tomorrows, while also helping out engineers in their day-to-day development.
    Technologies: Ruby on Rails, Tomcat, JRuby, Logstash, CircleCI, Apache JMeter, Splunk
  • Software Craftsman

    2008 - 2011
    • Built a social web application with a REST API for mobile clients.
    • Invented a re-usable REST client for limited environments (J2ME) and built a portable mobile client using LWUIT.
    • Automatized deployment and EC2 machine setup, using Puppet.
    • Migrated the app to an early version of JRuby and performed routine maintenance, including fixes and implementing new features for the server.
    • Became involved in open-source libraries and learned what open-sourcing a project entails.
    Technologies: REST, Rails, JRuby, Trinidad, jQuery, Facebook Platform, J2ME, LWUIT, MySQL, Git, EC2, Puppet
  • JavaEE Consultant

    2009 - 2010
    Ceska Sporitelna, a.s.
    • Converted the existing (huge) infrastructure of a portal project, under Maven.
    • Automatized build as much as possible, including generating setup files for a custom IDE.
    • Helped the bootstrap of existing(internal) and new developers.
    • "Hacked" a custom, third party application to run nicely on an existing infrastructure, since the new version was having issues with the logging libraries.
    • Supported user requirements and adjusted third-party app to meet the needs of the bank's intranet.
    Technologies: JaveEE, Beehive, WebLogic Server 10, WebLogic Portal 10, Oracle 10g, Maven, TeamCity
  • Senior Developer

    2007 - 2008
    Tempest, a.s.
    • Created a flexible, customizable and secure oneĀ­-time-password solution, based on smart cards, from scratch.
    • Built smart-card "hacking" tools to resolve an EMV-compatible communication protocol, with an OTP pocket-reader.
    • Helped and managed a small team of junior and mid-senior developers.
    • Developed an Identity module to integrate the company's user management software with Sun's Identity Manager.
    • Built a few Nagios monitoring portlets for SysAdmins.
    Technologies: JavaCard, Global Platform, Swing, AOP, PKI, JCE, LDAP, Groovy, Spring 2.x, MySQL, Sun Access Manager, Sun AppServer, Sun Portal Platform, Portlets, Sun Identity Manager
  • Software Engineer/Integration Consultant

    2006 - 2007
    Adastra, s.r.o.
    • Created a messaging layer to communicate with existing services over ESB.
    • Crafted custom JSF UI components for the client side.
    • Performed optimizations, by moving parts of the Java decision logic into PL/SQL.
    • Built a support project for SQL migrations between releases.
    • Built a project for reading FoxPro Database files seamlessly (in JDBC).
    Technologies: JavaEE, JSF, EJB, JDBC, JMS, WS, ESB, Spring, PL/SQL, Hibernate 3.x, JBoss 4.x, Oracle 10g
  • Team Leader

    2005 - 2006
    Dupres Consulting
    • Built a domain model based on an existing design and requirements.
    • Exposed a remote business-service layer for a front-end user interface.
    • Developed a web prototype, which consumed the services and showcased design practices.
    • Resolved back-end issues and lead its development with two others.
    • Helped newcomers on both ends (back-end and front-end) to get into the work flow.
    Technologies: J2EE 1.4, EJB 2.1, Hibernate 3.0, RMI, MyFaces 1.1, JBoss 4.0, MySQL 5.0, Oracle 10g


  • JRuby (on Rails) (Development)

    Worked on ActiveRecord-JDBC-Adapter, JRuby-Rack, Trinidad and much moret.

  • Adtile (Development)

    As ads met mobile, the API scales just right from the cloud.

  • eVue (Development)

    Make sure those industrial laundry machines keep working as they should.

  • PeersONE (Development)

    First social network that pushes you off-line ... low-cost and retro!

  • INET (Development)

    Portlets every where you look on the site of the largest bank in Czechia.

  • CMS TatraBanka (Development)

    Collateral - collateral - collateral ... collateral management it is!

  • MAIS (Development)

    Facing some ~50.000 students daily as their central information system at the University, and still counting.


  • Languages

    Java, JRuby, JavaScript, SQL-99, Groovy, Scala
  • Frameworks

    Ruby on Rails (RoR), Sinatra, Celluloid, Grails, Spring, JavaServer Faces, Adhearsion
  • Libraries/APIs

    Rhino, jQuery, Node.js
  • Tools

    Apache Tomcat, Git, Maven, Apache JMeter
  • Platforms

    JEE, Linux, TorqueBox, Oracle, Heroku, AWS EC2
  • Storage

    Cache, MySQL, JBoss Cache, PostgreSQL, JBoss AS, MySQL/MariaDB
  • Paradigms



  • Master's degree in Mathematical Informatics
    2000 - 2005
    University of P.J.Safarik - East Coast
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