About Konstantin Rafalskii
23 years in software, 18 of them in Rails. I work as a long-term technical partner on one product, rather than as a fixer for a queue of small tasks.
Full overlap with European business hours, and 9am–6pm US Eastern.
What I do
- Rails architecture, upgrades and legacy rescue (5.x/6.x → 7.x/8.x)
- AI and LLM integration: OpenAI, Anthropic, RAG, agentic workflows
- Performance and scale for systems that outgrew their design
- Complex integrations: healthcare (HIPAA/EMR), payments, e-commerce, social APIs
- Architecture reviews, audits and technical due diligence
Background
I was CTO of an international loyalty platform for eight years, from 2008 to 2016: two to three teams of four to five developers, more than twenty integration modules designed and led, and a department moved to a distributed team. From 2020 to 2022 I was engineering manager for a UK company — eLocker — where I built the team, set the engineering standards and the delivery process, and redesigned the architecture.
I have been freelance since 2015; on Upwork I am Expert-Vetted, with 43 clients, 21,500+ hours and 100% Job Success. I am a certified Project Management Professional, valid to 2032, and I hold a BSc in Applied Mathematics with honours.
How I work
- One long-term product rather than a queue of small tasks.
- In your repository, under your review process; the code stays in a state your team can maintain without me.
- Every engagement starts with a written review and ends with a written handover.
I do not take work in gambling, adult content or alcohol.
The stack
Ruby on Rails (2.x–8.x), PostgreSQL, Sidekiq, Redis, Hotwire (Turbo/Stimulus), React, AWS, Docker, RSpec.
OpenAI, Anthropic, RAG, vector search, function calling, multi-model routing.
Working together
Tell me about the product, what is going wrong, and the Rails and Ruby versions. I reply with what I would do first.
Full overlap with European business hours, and 9am–6pm US Eastern.
43 clients, 21,500+ hours, 100% Job Success — the reviews are on Upwork.