10/09/2026 updated
VI
100 % available
Staff Back-end Engineer | Distributed Data-Intensive Systems | AI-Driven | Scala
Warsaw, Poland
Only remote
Specialist diploma (5-year, MSc equivalent) in Computer Science, Belarusian State UniversityAbout me
Back-end engineer with 20 years of experience, the last ten building distributed systems. I've worked extensively and owned systems where reliability and data correctness matter: event-sourced platforms, high-volume data processing and production systems that need to be stabilized.
AI AgentsOpenAIGCPJava (Programming Language).NET FrameworkAkka (Toolkit)Amazon Web ServicesC Sharp (Programming Language)Distributed SystemsJava Virtual Machine (JVM)Python (Programming Language)PostgreSQLScalaSystems DesignDocker Container
What I can bring
- Back-end architecture and design for distributed and data-intensive systems: event sourcing, CQRS, recovery after failures, effectively-once processing.
- End-to-end ownership of core back-end components, from design to deployment and operation.
- Technical leadership: leading teams, reviewing architecture, and mentoring engineers.
- Stabilizing production systems: finding the root causes of recurring incidents, latency problems and data inconsistencies, including in event-sourcing and projection layers.
- Agent-driven development: setting up structured workflows of requirements, design and implementation, and recognizing where agents fail.
Recent experience
- Reflek.io (2024 – present), Lead Back-end Engineer: led the back end and its team for a digital twin and manufacturing execution system running on the production lines of a major European car manufacturer. Cut production incidents from several per week to fewer than one every few months, and improved P99 API latency from 3 s to under 300 ms at 700 req/s. Now designing the data core of the platform’s AI-first rebuild.
- VaultMe (2016 – 2023), Staff Back-end Engineer: founding engineer of a cloud data migration product that grew to over 10,000 customers, including Princeton and Stanford. Owned the core migration engine, which ran hundreds of concurrent migrations with automatic failure recovery and migrated hundreds of millions of items.
- CompatibL (2009 – 2016): trading, risk and operations systems for Bank of America Merrill Lynch, JP Morgan, the World Bank and other major banks, as engineer, architect and project lead for teams of up to nine.
Technical skills
- Languages: Scala, Python, SQL; earlier C# and Java
- Frameworks and libraries: Akka, ZIO, functional programming in Scala
- Architecture: distributed systems, event sourcing, CQRS, system design
- Cloud and infrastructure: GCP, AWS, Kubernetes, Docker, CI/CD
- Databases: PostgreSQL, MySQL
- AI-assisted development: Claude Code, OpenAI Codex, agentic workflows
Worked with distributed teams across European and US time zones for over 15 years, the last five fully remote.
Based in Warsaw, Poland (CET). Open to remote full-time and contract roles.
Experience
Professional experience10+ years
Freelancer since2026
Languages
EnglishFluentPolishGoodRussianNative speakerBelarusianNative speaker
Project history
Enterprise digital twin and real-time manufacturing execution system, live on the main production lines of two plants of a major European car manufacturer. Hybrid cloud/edge deployment.
Production platform
- Owned the back end as its technical authority, shaped its roadmap and led a team of 3 engineers.
- Main technical contact for the AI analytics and customer integrations teams, which built on my APIs.
- Made an inherited system production-ready, tracing root causes in its event-sourcing and projection layers, including a defect in Akka itself:
- Cut production incidents from several per week to fewer than one every few months.
- Improved P99 API latency from 3 s to under 300 ms at 700 req/s.
- Final escalation point for production reliability: led incident response, recovery and data restoration across multi-terabyte event stores.
AI-first platform rebuild (since Apr 2026)
- Owned the data core design and implementation of its multi-tier event storage: Raft-replicated RocksDB hot tier, S3-backed archive.
- Redesigned the projection layer for effectively-once processing and reliable recovery after outages, and implemented its core.
- Ran a structured agentic workflow on Claude Code and OpenAI Codex, from requirements to designs and plans that agents built with TDD.
- Identified agent failure modes, such as test gaming and code never wired into production, and proposed static reachability analysis to catch the latter.
A cloud data migration product that moves data between cloud providers for individuals and businesses. By the end of 2023 it had grown to over 10,000 customers, including Princeton, Stanford.
- Joined as the first engineer after the CTO. Led a complete rewrite of the prototype into a production platform, and owned its core migration engine end to end.
- Designed the engine around pluggable connectors for major cloud providers, covering email, files, calendars and contacts. Over the years it migrated hundreds of millions of items.
- Built reliability into the engine as a core guarantee, running hundreds of concurrent migrations with automatic recovery from failures, no duplicated data, and robust handling of provider rate limits. This made it viable for enterprise and university customers.
- Drove the adoption of ZIO alongside Akka for tighter control over concurrency, error handling and system structure, and established Scala and functional programming best practices across the codebase.
- Mentored a junior developer in coding practices and design, growing her into the owner of the connector modules. Served as the team's go-to expert on Scala and led knowledge sharing on functional programming.
- Shared responsibility for the AWS infrastructure, owning the engine's Docker-based deployments, CI pipelines and database migrations, and drove ongoing cost optimization.
- Built supporting tooling, such as metrics infrastructure and dashboards and a migration-time estimation model.
Financial technology consultancy delivering trading, risk and derivatives systems for major banks.
Consultant, XVA Model Validation, Commonwealth Bank of Australia 2015 – 2016
- Built a model validation framework and automated test suite for an XVA system. The project opened a new line of business for the company.
Project Manager & Architect, Asset Allocation Workbench, World Bank 2014 – 2015
- Led a team of up to 9 building an asset-allocation training and analysis tool used by investment managers in 30+ central banks.
- Set up and ran the development process, estimated and planned the project from the ground up, and mentored team members.
- Owned specification, architecture and code quality. Delivered on time and on budget, and presented it at the World Bank’s Workshop on Applied Asset Allocation.
Earlier CompatibL projects 2009 – 2014
- UOB: designed and built a real-time integration of Murex, Calypso and WallStreet for pre-deal FX and IR limit checking (Java).
- JP Morgan Chase: team lead and architect for an operations workstation automating middle- and back-office workflows (C#).
- BofA Merrill Lynch: senior engineer on a bond and CDS market-making workstation used by 400+ traders globally, including on-site work in New York, Hong Kong and Singapore (C#).