Sergei Udalov
Senior Backend Engineer
sergei.udalov@gmail.com · linkedin.com/in/sergeiudalov · github.com/sergio-fry · Remote · European hours
Dear GitLab team,
I'm applying for the Senior Backend Engineer (Plan: Spec-Driven Development) role. Turning a stated intent into a refined work item, a plan and verified, mergeable code is the most interesting problem in our field — and it sits where my background does: large Rails codebases and a serious interest in AI/LLM engineering.
For 15+ years I've built and owned backend systems that carry real traffic — e-commerce, fintech, nation-scale infrastructure. I've taken products from zero to production, migrated systems under live load, and cut inventory synchronization from 20 minutes to 2 with ClickHouse. Most of it was cross-team, mentoring included.
Technically I'm strongest in Ruby and Rails, with PostgreSQL, Kafka, ClickHouse and Kubernetes as daily tools. I treat API design, data models and observability as design constraints, and I've led monolith-to-microservices work and built shared frameworks other teams adopted. On the AI side I built an LLM voice bot with LangChain that took on about 7% of routine payment inquiries — an early lesson in measuring the quality, cost and failure modes of model-driven workflows.
What I bring
15+ years Ruby on Rails in production at scale
PostgreSQL · Kafka · ClickHouse · Kubernetes · API design
LLM features, agentic workflows, evaluation mindset
What draws me to GitLab is an all-remote, async-first culture and genuinely early-stage product work. I work in writing — specs and docs others can pick up — and I'm comfortable shaping scope with product and users. Python is my honest gap: I've shipped Ruby, Go and PHP, and I'd ramp up in Python without overselling the depth.
I work fully remote and keep European hours, so a distributed team across Canada and Europe fits my normal working day. I'd be glad to talk about how I can help build the intent-to-code loop. Thank you for your time and consideration.
Best regards,
Sergei Udalov