Location: Ukraine (UTC+2 / UTC+3)

Remote: Yes

Willing to relocate: No

Technologies: Ruby, Ruby on Rails, PostgreSQL, Sidekiq/Redis, Hotwire, JavaScript, TypeScript, React, GraphQL/REST/Grape, RSpec/Capybara, Python/FastAPI, PyTorch/Hugging Face, LLM APIs (OpenAI, Anthropic), Docker, AWS/DigitalOcean

Résumé/CV: https://katatsu12.github.io/

Email: den.zubrytskyi@gmail.com

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Senior full-stack Rails engineer, 9 years commercial. I ship AI features into production SaaS — not demos.

Most recent: Review Copilot, an AI review-analytics app live on the Shopify App Store, built and shipped solo end to end. Rails 8 backend, plus a DistilBERT multi-label classifier I fine-tuned via knowledge distillation and serve from a Python/FastAPI microservice, orchestrated through Sidekiq. Every recommendation cites the reviews behind it, with a verification pass that flags claims the underlying feedback doesn't support.

Before that: an AI-driven ABM platform (Rails + React) with LLM content-generation pipelines, marketplace products with payments and geolocation, and a legacy CoffeeScript → Turbo Frames migration.

Looking for senior IC work on a Rails product — ideally somewhere LLM or ML features are on the roadmap rather than bolted on.