Oskar Szrajer

Oskar Szrajer

Senior Software Engineer · Ruby / Elixir · AI-enabled web development

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Volunteer Experience

  • Open Source Contributor

    Various projects (details on GitHub)

  • Speaker

    TRUG, Wrocław.rb

  • Lecturer

    University of Gdańsk (Ruby, Elixir)

  • Mentor

    Rails Girls Łodź & Tricity

  • Founder

    TRUG – Tricity Ruby User Group

  • Judge

    Ruby Rampage

Oskar Szrajer

Oskar Szrajer

Senior Software Engineer · Ruby / Elixir · AI-enabled web development

Experience

  • Founder / Owner

    Gotar

    Apr 2011 – ongoing Gdynia, Poland / Remote
    • Founder and owner of Gotar, a one-man Ruby/Elixir consultancy specializing in web development
    • Developed numerous web applications and systems for clients worldwide
    • Own product: Rails Radar (railsradar.dev), a live Rails 8 job aggregator tracking 1,800+ listings from 25+ sources, built with Hotwire, Solid Queue and Kamal deploy.
    • Serving as business consultant for Rebased Software House

  • Senior Software Developer

    Impactpool

    Sep 2021 – ongoing Remote
    • Helping Impactpool with software development and building/leading the tech team. Impactpool is a Ruby on Rails 8 platform connecting humanitarian employers with qualified talent, featuring job matching, talent pools, analytics, and integrations with BigQuery and external APIs.
    • Utilized modern Rails tools including Hotwire (Turbo and Stimulus) for dynamic interfaces, ViewComponents for reusable UI elements, and Stimulus controllers for enhanced interactivity.
    • Integrated advanced technologies such as Puppeteer for web scraping, Dry-rb for business logic, and Sequel ORM for database management.
 Oskar Szrajer

"Done is better than perfect."
—Sheryl Sandberg

Bio

My main specialization is back-end web application development in Ruby and Elixir, with over 20 years of experience in software engineering, including deep expertise in Linux system administration and DevOps practices.

I've been a Ruby/Rails developer for more than 15 years, working remotely for most of my career and leading teams in building scalable web applications for international clients.

I'm a big advocate of TDD, BDD, and Agile practices, emphasizing clean code, continuous integration, and collaborative development.

Throughout my career, I've served as a Senior Ruby Developer, Team/Technical Lead, and Software Engineering Manager, managing both remote and on-site teams, mentoring developers, and contributing to open-source projects.

Skills

  • Ruby
  • Rails
  • Elixir
  • PostgreSQL
  • SQL
  • NoSQL
  • RSpec
  • TDD
  • BDD
  • Dry-rb
  • REST APIs
  • GraphQL
  • BigQuery
  • Docker
  • Linux
  • Git
  • AWS
  • CI/CD
  • Monitoring
  • AI-assisted development
  • LLM application design
  • Prompt engineering
  • Machine learning foundations
  • Data analytics
  • HTML
  • CSS
  • JavaScript
  • TypeScript
  • React
  • Node.js

Experience

  • Senior Backend Developer

    Belighted

    Oct 2018 – Aug 2021 Remote
    • Hannah Online – backend for financial forecasting app (Rails, Ruby, Dry-rb, RSpec, PostgreSQL, GraphQL)
    • AXS – backend for car sharing platform (Rails, Ruby, Dry-rb, RSpec, PostgreSQL, External APIs, SOAP)
    • Admeet – backend for GDPR generator (ROM, Roda, Ruby, Dry-rb, RSpec, PostgreSQL, GraphQL)
    • Helping company to grow

  • Co-owner

    Ragnarson

    Jul 2014 – Oct 2016 Sopot, Poland / Remote
    • Established Tricity office branch
    • Contributed to company growth from 10+ to 30+ developers
    • Hired and trained new developers, including over 100 interns
    • Supported clients as Project Manager and Account Manager

  • Senior Ruby Developer

    Ragnarson

    Apr 2011 – Jun 2016 Sopot, Poland / Remote
    • Getmii – Geo-based instant messaging backend system (API for mobile iOS and Android apps) (ROM, Roda, Ruby, Dry-rb, RSpec, Postgres, ElasticSearch, REST API)
    • Masii – Credit Cards & Insurances comparison platform (ROM, Roda, Ruby, Dry-rb, RSpec, Postgres, REST API)
    • Locafox – Geo-location price comparison platform (Ruby, Roda, PostgreSQL, ElasticSearch, RSpec, REST API)
    • MaMyMo – high-performance backend system supporting Google Ads platform management(JRuby, Threads, Sinatra, PostgreSQL, Redis, RSpec)
    • Teon – Car manuals (Ruby, Rails, ActiveAdmin, MongoDB, RSpec)
    • Tripsta (TravelPlanet) – high-performance support systems (>3000 req/s) (Ruby, Goliath, Sinatra, Redis, RSpec)
    • Bellegs – Spree-based e-commerce platform (Spree, Rails, RSpec, PostgreSQL)

  • Web developer, DevOps

    Renault Trucks (Bernard Trucks)

    Aug 2006 – Sep 2010 Gdynia, Poland
    • Built and managed Linux-based servers
    • Built company website using PHP and SQL
    • Built internal software using PHP and SQL

  • Web developer, DevOps

    ITM Centrum Komputerowe

    Apr 2006 – Jul 2006 Gdańsk, Poland
    • Built company website using PHP and SQL

  • Lecturer

    ITM Centrum Komputerowe

    Dec 2005 – Jul 2006 Gdańsk, Poland
    • Lecturer on professional courses including Linux System Administration, Flash (ActionScript), Photoshop, and PHP

Volunteer Experience

  • Open Source Contributor

    Various projects (details on GitHub)

  • Speaker

    TRUG, Wrocław.rb

  • Lecturer

    University of Gdańsk (Ruby, Elixir)

  • Mentor

    Rails Girls Łodź & Tricity

  • Founder

    TRUG – Tricity Ruby User Group

  • Judge

    Ruby Rampage

AI & computational intelligence

AI-aware software engineer with an academic background in computational intelligence and a practical focus on applying AI to reliable web products.

  • AI-assisted software engineering: research, prototyping, code review and developer workflows
  • LLM-enabled applications: evaluation, prompt design, structured outputs and API integration
  • Data-informed product development, automation and analytics

Education

  • MSc, Computational Intelligence

    University of Gdańsk

    Software engineering, algorithms and computer systems

    Artificial intelligence, machine learning and computational methods

    2008 – 2010

  • BSc, Computer Science

    University of Gdańsk

    2005 – 2008

Languages

  • Polish
  • English

Passions

  • Martial Arts
  • Hiking
  • Photography
  • Cooking
  • Fantasy & Sci-Fi novels
  • Mountain biking
  • Baking
  • Cinematography
  • Diving
  • Bushcraft
  • Motorbikes
  • Motorcycle Travel