HI, I’m Oskar Lakner a professional Ruby on Rails developer

I am passionate about Ruby on Rails. I am a devoted, conscientious and reliable person, able to work efficiently both by myself and as part a team. Self-development is important to me, so when I take on a project, I always hope for a challenge - they are the best source of knowledge. When I’m not programming, I enjoy reading books and listening to rock music.

My Skills

  • Ruby
  • Rails
  • HTML5
  • CSS3
  • JS
  • GIT
  • jQuery
  • PostgreSQL
  • CoffeeScript
  • MySQL

My Works


2014-10-01 - 2015-07-01

Online tool to create highly customized surveys.

Technology stack: Rails 4.2, MySQL, Resque, Backbone.js

Things I did for this project:
- implementing custom internationalization system based on regular expressions
- implementing highly advanced DSL in Ruby
- ongoing maintenance

2014-09-01 - 2015-07-01

Zappistore is an online research marketplace. Its automated platform uses insight from their partners and global panel companies to provide quality insight into market research.

Technology stack: Rails 3, MySQL, Amazon AWS, Vimeo API, Resque

Things I did for this project:
- video transcoding as a background task based on Vimeo and Amazon S3
- custom rake tasks connected with background
- customizing ActiveAdmin
- ongoing maintenance

2014-08-01 - 2014-09-01

A breakthrough ebook distribution model which meets readers', writers' and publishers' expectations. Not only can you publish your books, but you will also… Well let’s just say you will be pleasantly surprised.

Technology stack: Rails 4, PostgreSQL, Calibre - ebook conversion, Backbone.js, Marionette.js, CoffeeScript, Bootstrap 3, DataTables - jQuery Table Plugin applied in admin panel

Things I did for this project:
- implementing highlighting system for best author
- implementing feature that allows users to choose the best published book
- implementing system that allows users to choose the top contributors
- implementing voting feature that allows users to choose the best authors
- application ongoing maintenance

2014-07-01 - 2014-08-01

Uscreen is a great platform for publishing and monetizing videos.

Technology stack: Rails 4, PostgreSQL, Amazon AWS, Angular.js

Things I did for this project:
- improvements to video playlist creator in Angular.js
- implementing responsive web interface (for mobile)
- improvements and cleanups related to upgrade from Rails 4.0.8 to 4.1
- application ongoing maintenance

Compare Car Buyers

2014-05-01 - 2014-07-01

Portal based on Ruby on Rails 3 which makes available for a fee contact to people wishing to sell their cars. Portal is targeted for Great Brittain. Application differentiate three types of the users:

- The car seller
- The contact buyer
- The administrator

At first, the client inputs registration number of his car using sites form, where DVLA (Driver and Vehicle Licensing Agency) using SOAP 1.2 API checks if the car exists. There are two paths possible here:

- The car exists - form data are being prefilled with data provided by DVLA response and the client enters only his own personal contact data
- The car could not been found - the client is being redirected to a dedicated form, where he is asked to enter car data such as the model, the brand, vehicle capacity and the contact data

Every company is must provide their credit card information used by the Sagepay gateway for processing what results with a secured token with which all business clients are allowed to purchase contact data with 1-click-buy system

If the car is being accepted registered companies are allowed to preview owners contact offer if his address fits the area radius predefined by the given company.

London Institute

2014-04-01 - 2014-05-01

Codes for language courses saling platform based on Ruby on Rais 3 with payment gateway to ( Solution allows to upload CSV files with assigned codes to different levels of the course (beginners, intermediate, advanced) with codes accessibility monitoring. Whole process is managed as follows:

- The client chooses the courses he’s interested in

- At this stage one creates his own object with his credentials and personal data prepared for payment gateway (advertisment agreement, name, surname etc.)

- There is a hash generated for the payment/the checksum (to secure the payment), two returning links (for payment success and failure) and the client is being redirected to ( to perform the payment

- After the payment on ( the system calls it with POST request the preconfigured endpoint, where the incomming IP address is being checked, checksum is being decoded and if all data is correct, the client receives the code to the course he has paid for

- There are three scenarios system covers in case of the failure, that is:
a) if the checksums don’t match, the client is being informed about the error and asked to contact the portal administrator
b) if there is no more course codes availablethe client issued for, the allert to the administrator is being sent together with the email to the client informing him that the request is being processed
c) if the request is received from the IP address that does not belong to ( endpoint will not react at all


  • Senior Ruby on Rails developer

    Paladin Software

    2016-04-01 - Present (almost 2 years)

    Kraków Area, Poland

  • Senior Ruby on Rails developer

    Bent Pixels

    2015-06-01 - 2016-04-11 (11 months)

    Kraków Area, Poland

  • Ruby on Rails developer


    2014-07-01 - 2015-06-01 (11 months)

    Wroclaw, Lower Silesian District, Poland

  • Programista Ruby on Rails

    Euro Bank S.A.

    2013-12-01 - 2014-07-08 (7 months)

    Wrocław Area, Poland

  • Software Developer

    SMT Software

    2013-07-01 - 2014-07-01 (about 1 year)

    Wrocław Area, Poland

  • PHP Developer

    Internet Dreams Studio

    2013-08-01 - 2014-06-11 (10 months)

    Wrocław Area, Poland

  • Front-end developer


    2013-03-01 - 2013-07-05 (4 months)

    Wroclaw, Lower Silesian District, Poland

  • Front-end developer

    2012-07-01 - 2013-03-09 (8 months)

Latest post

Common mistakes juniors make in their CV

I was recently invited to a job fair organised by Michał Makaruk from []( where I gave a talk about Paladin Software, the company I work for. After the presentation, some attendees asked me to review their CVs. These discussions inspired me to put together a few points regarding how (not) to present your resume as a junior tech employee or industry hopeful.

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