(GENERATED FILE - do not edit.) (Source: profile/cv.yaml - python3 profile/cv-build.py) (PDF: bash profile/build-western-cv-pdf.sh) Sergei Udalov Staff Backend Engineer | Distributed Systems | Ruby/Rails sergei.udalov@gmail.com | @SergeiUdalov (https://t.me/SergeiUdalov) | +7 916 627-26-58 | LinkedIn (https://www.linkedin.com/in/sergeiudalov/) | GitHub (https://github.com/sergio-fry) | Remote | EU Time Zone SUMMARY Staff-level Backend Engineer with 15+ years of experience building high-load and distributed systems, primarily with Ruby/Rails. Hands-on engineer focused on system architecture, scalability and reliability, with deep experience in PostgreSQL, Kafka, ClickHouse and Kubernetes. Led architecture and delivery across e-commerce, fintech and consumer platforms, from modernizing legacy systems to launching new products from scratch. Experienced in DDD, event-driven architecture, observability and engineering productivity. Practical experience applying AI/LLM: delivered production solutions built on LLMs and agentic approaches, including a voice bot and a code-review agent. Independently developing agentic engineering and applying AI agents in my own engineering projects. SKILLS Languages & Backend: Ruby, Ruby on Rails, PostgreSQL, Kafka, Redis, ClickHouse, Go Architecture: Distributed Systems, Event-Driven Architecture, Microservices, DDD, API Design, Legacy Modernization Infrastructure & Observability: Kubernetes, Docker, AWS, GitLab CI/CD, OpenTelemetry, Prometheus, Grafana AI/LLM: LLM orchestration, AI agents, LangChain EXPERIENCE Lead Backend Engineer - Dixy Nov 2025 - Present Core backend for the Dixy mobile app: integrations, APIs, performance and delivery. - Improved inventory synchronization 10x (20 min -> 2 min) via ClickHouse->PostgreSQL migration, batch API-Hub integrations, and parallel incremental processing. - Owned full-cycle delivery of cross-cutting backend changes (requirements -> production) for a high-traffic mobile inventory and integration system serving 2,000 stores (~1,000 RPS, 800 GB+ data). - Parallelized GitLab CI pipelines, cutting pipeline wait time from ~30 min to ~5 min for two engineering teams. Technical Lead - Raiffeisen Bank Jul 2025 - Sep 2025 Banking infrastructure; technical leadership across three cross-functional teams. - Led architecture and delivery of a banking infrastructure migration: rebuilt C4 documentation for ~50 services, introduced distributed tracing across 20 services, and drove the migration to ~80% completion. - Designed and delivered an AI voice bot using LangChain and LLM orchestration, automating ~7% of routine customer payment inquiries. Product Team Lead - Samokat.tech (ecom.tech) Apr 2023 - Jun 2025 Scalable e-commerce platform (consumer apps); launched products from scratch. - Architected and delivered backend for 3 new consumer products from zero to production (150 RPS, 800K+ users, 20 GB data) - Kafka event streaming, WebSocket real-time layer, DDD boundaries. - Built a Go platform service streaming Kafka events to WebSocket clients across multiple products, handling ~500 concurrent connections and ~50 events/sec. - Built an AI code-review agent (Ruby service on GitLab webhooks) that analyzed changes against project conventions and flagged common security and performance issues. - Established Domain-Driven Design as the architectural standard and a lightweight technical-debt process adopted by multiple product teams. Senior Developer -> Team Lead -> Ruby Practice Lead - Balance Platform Sep 2019 - Apr 2023 Lending-as-a-Service (LaaS) platform: credit automation, internal platform, Ruby standards. - Built in the LaaS credit-automation domain; optimized core performance and SQL efficiency; led monolith->microservices extraction. - Designed an internal RPC protocol and built the in-house "Core" framework adopted by multiple service teams. - Increased system throughput and reliability; built a ClickHouse analytics module and business-event collection for analytics. - Defined code-review standards and a Ruby competency matrix adopted across the engineering organization. Team Lead - Soft Telematics Apr 2017 - Aug 2019 Nation-scale toll-road systems: Platon (truck toll collection), Oboz (freight documents), and Avtodor toll roads. - Built reporting services and mobile APIs for Platon, a nation-scale toll-collection system (1M+ vehicles); implemented automated test pipelines and reliable test-database builds across modules. - Extended the Oboz freight-document platform with document-processing and reporting capabilities for freight carriers. - Built admin interfaces and payment reporting for Avtodor toll-road systems. Ruby Developer - Source[Lab] Dec 2015 - Apr 2017 - Integrated the Idibu CV-advertising API with the Hiring Hub HR service; built a document-management system for ORAC (UK clients). - Migrated projects from vendor-locked CI/CD (GitHub, Codeship, Heroku) to open-source GitLab CI and Dokku. Ruby Developer - SeoPult Mar 2014 - Dec 2015 Backend services and public APIs for an SEO platform. - Built the internal backend core - Sidekiq workers, remote RPC, RESTful API - and sped up JSON/XML/text generation for fast API responses. - Worked on a high-load HTTP crawler in Go with RPC access; integrated the QIWI payment system. Ruby Developer - Social Quantum Oct 2012 - Mar 2014 - Reworked the core system's RPC API; migrated PGQ workers to the new internal API. - Built a QIWI payment gateway via REST and financial report generators. Ruby Developer - Undev.ru Aug 2011 - Oct 2012 - Built a payment-acceptance API integrating PayPal, PerfectMoney and other gateways; automated financial reporting with Google Analytics. PHP / Ruby Developer - HROS | High-Web | June Marketing | Sportweek 2006 - 2011 - PHP/Symfony: online hotel-booking systems (HROS, High-Web). Ruby/Rails: 10+ e-commerce sites and in-house CMS (June Marketing); sports news portal with live broadcasts (Sportweek). PROJECTS & PUBLICATIONS - HeavyTech Podcast - host, covering AI/LLM engineering, system architecture, and backend patterns. - RubyRussia 2023/2024/2025 - speaker on architecture, test automation, and database migrations. EDUCATION Moscow Aviation Institute (National Research University) - 2008 Specialist degree in Applied Mathematics and Physics (comparable to Master's). Mathematician, Systems Programmer.