Oskar Szrajer — Software Engineer CV

Gdynia, Poland · [email protected] · +48 608 019 078 · gotar.info

linkedin.com/in/oskarszrajer · github.com/gotar

Summary

Ruby/Rails engineer building full-stack products and leading remote teams. Operate independent AI applications with LLM output evaluation, structured extraction and tool-enabled assistants.

Professional experience

Impactpool — Senior Software Developer

Sep 2021–Apr 2026 · Remote · Hands-on development and technical team leadership

Helped build and lead a distributed team delivering a Rails 8 recruitment platform for humanitarian employers: job matching, talent pools and analytics.
Built API/BigQuery and Hotwire integrations (Turbo, Stimulus, ViewComponent); Puppeteer, dry-rb, Sequel.

Belighted — Senior Backend Developer

Oct 2018–Aug 2021 · Remote

Built financial forecasting (Hannah Online), car-sharing (AXS) and GDPR documentation (Admeet) backends with Rails, Roda/ROM, PostgreSQL and RSpec.
Integrated GraphQL, SOAP and external APIs; used dry-rb for business logic.

Ragnarson — Senior Ruby Developer / Co-owner

Developer: Apr 2011–Jun 2016 · Co-owner: Jul 2014–Oct 2016 · Sopot / Remote

Worked on Tripsta support systems handling 3,000+ requests/second, mobile messaging APIs and Google Ads backends; Ruby, JRuby, Sinatra, Redis, PostgreSQL.
Established the Tricity office; helped grow the company from 10+ to 30+ developers, hired and trained 100+ interns, and managed client relationships.

Independent consulting & AI products

Gotar — Founder / Independent Software Engineer

Apr 2011–present · Gdynia / Remote

Run a Ruby/Elixir consultancy for international clients; provide business consulting for Rebased.
Readarr: deployed personal AI reader; 1,900+ LLM-translated, automatically reviewed chapters. Structured review, corrections, deterministic checks; model quality/latency/cost comparisons.
Rails Radar (railsradar.dev): live Rails product with 5,100+ collected listings and 2,400+ AI extraction records, confidence-gated facts and audit history. Hotwire, Solid Queue, Kamal.
Personal AI Assistant: streaming, tool use, knowledge retrieval and Slack/Telegram gateways.
Multi-Agent Workflow Assistant (MVP): agent manifests, isolated working directories and validated JSON results.

Core skills

Backend: Ruby · Rails · Roda · Hanami · Elixir · Sequel · ROM.rb · dry-rb · REST/GraphQL · RSpec/TDD · Sidekiq

Web & UI: JavaScript · TypeScript · React · Node.js · Hotwire · HTML/CSS · Tailwind CSS · Figma

SQL & NoSQL: PostgreSQL · MongoDB · Redis · Elasticsearch · Query optimization · Caching

Delivery & access: Linux · Docker · AWS · CI/CD · GitHub Actions · Kamal · OAuth/OIDC · Sentry

AI engineering: RubyLLM · Structured outputs · Tool calling/MCP · Agent orchestration · RAG · pgvector · LLM evaluation

Education & languages

MSc, Computational Intelligence — University of Gdańsk, 2008–2010
BSc, Computer Science — University of Gdańsk, 2005–2008

Languages: Polish · English