Hi 👋🏻 I'm Yegor Usoltsev

I'm an experienced backend and infrastructure engineer based in Minsk, Belarus, with a strong background in the JVM ecosystem.

For 10+ years, I've built backends, and more recently data pipelines, for web and mobile products at startups and mid-sized enterprises. My work starts with a business problem, and I stay responsible for what I put into production. I aim for elegant and efficient solutions and believe in the power of simplicity in creating complex systems. AI agents are part of my daily work and help me move faster.

TL;DR Buzzwords

Work Experience

ITRex Group (2025 – Present)

Senior Full-Stack Engineer @ Digital Health Platform (2025 – Present)

• Own the food and recipe catalogs and the Kotlin/Spring API behind 1M+ meal logs a day.
• Integrated AI meal recognition, adding hedging and circuit breakers around 30+ second LLM calls.
• Extended the food database to non-English foods, taking AI food logging beyond the US.
• Building a Python ETL pipeline that imports, normalizes, and classifies provider food data.
• Cut iOS payment fees from ~30% to ~3% by moving subscriptions to Stripe with a new React checkout.
• Write most of my code with AI agents and share MCP and prompting practices with the team.

SaddleCourt (2023 – 2024)

DevOps Engineer @ Insurance Platform (2023 – 2024)

• Designed and maintained a robust AWS infrastructure using Kubernetes and Terraform.
• Reduced AWS costs by 50% through spot instances, efficient scaling, and resource right-sizing.
• Set up and optimized an Apache Airflow cluster for efficient ETL workflows.
• Implemented mass email distribution with analytics to track delivery, opens, and clicks.
• Configured a reliable backup system to ensure data integrity and fast recovery.

iTechArt Group (2021 – 2023)

Senior Java Developer @ Customer Intelligence Platform (2021 – 2023)

• Led a team, making architectural decisions and prioritizing tasks to deliver key features on time.
• Developed a flexible system for two-way synchronization between Salesforce and HubSpot.
• Integrated with Zoom and Slack to provide real-time communication analysis capabilities.
• Created an internal crowdsourcing platform that improves manual data labeling processes.
• Implemented RBAC using OPA to ensure differentiated access rights for application users.
• Identified and resolved performance bottlenecks in complex SQL queries.

Senior Java Developer @ Voice-Based Authentication Platform (2021)

• Led a migration project from a monolith to a microservices architecture.
• Developed modular architecture utilizing custom Spring Boot Starters and Spring Cloud.
• Enabled type-safe communication by generating client libraries from Open API definitions.
• Enhanced throughput of the voice recognition service by moving to non-blocking I/O.
• Implemented an automated build, test, security audit, and code release process.

DevOps Engineer @ Real Estate Market Intelligence Platform (2021 – 2022)

• Designed a highly available and fault-tolerant AWS infrastructure using infrastructure as code.
• Developed advanced CI/CD pipelines for efficient software delivery.
• Implemented a secure VPN for streamlined developer access to infrastructure.
• Provisioned a cloud-based environment enabling data scientists to process large datasets.
• Applied best microservice practices to refactor existing Python applications.

Rap Tech Studios (2020)

Senior Java Developer / DevOps Engineer @ Rap Fame (2020)

• Set up a cost-effective infrastructure on AWS ECS by utilizing EC2 Spot Instances.
• Implemented an automated deployment process leveraging GitLab CI/CD pipelines.
• Improved search results by configuring Elasticsearch analyzers, tokenizers, and filters.
• Created a highly optimized Instagram-like web-sharing page and audio-video player.
• Prototyped the frontend for a new admin panel with improved performance and usability.

Playtika (2019 – 2020)

Java Developer @ In-Game Chat System (2020)

• Performed complex load testing to determine the maximum throughput of the existing system.
• Doubled peak system performance and reduced memory consumption.
• Implemented XMPP extension for managing message receipts and unread message counts.
• Developed a file upload plugin that leverages S3-like storage instead of the regular filesystem.
• Built an API for editing and deleting messages to meet modern chat requirements.

Java Developer @ Multiplayer Gaming Platform (2019)

• Refactored code to avoid blocking calls in the event loop and handled reconnects gracefully.
• Improved serialization performance and reduced message size by transitioning to Protobuf.
• Updated platform documentation with reference implementation and examples.
• Streamlined documentation generation by integrating it into build and release workflows.

Yellow (2017 – 2019)

Java Developer / DevOps Engineer @ Water Delivery Service (2019)

• Implemented a sophisticated deployment pipeline utilizing GitLab CI/CD and Helm.
• Configured a monitoring solution for infrastructure and services using DataDog and Sentry.
• Prepared the infrastructure to meet the requirements for PCI DSS audits.
• Conducted interviews with candidates for Java and DevOps roles.

Java Developer / DevOps Engineer @ E-Commerce Traveling App (2018 – 2019)

• Adopted an API-first approach with Swagger for faster client-side development.
• Developed and deployed an automated image resizing solution on AWS Lambda.
• Integrated with Braintree API to enable online payment processing.
• Implemented chat functionality and real-time notifications using PubNub.
• Mentored junior developers and established code review standards.

Java Developer / DevOps Engineer @ Crowdsourcing Platform (2017 – 2018)

• Developed event-based communication between services with Apache Kafka.
• Implemented complex business logic based on state-machine concepts.
• Set up a highly available and fault-tolerant infrastructure using Kubernetes.
• Architected and maintained a CI/CD pipeline for production deployments.
• Optimized SQL queries and fixed concurrency issues for improved performance.

IBA Group (2015 – 2017)

Junior Java Developer @ Online Banking System (2015 – 2017)

• Optimized integration tests, resulting in a 50% reduction in average build time.
• Developed and integrated new REST API endpoints to replace legacy SOAP services.
• Proposed enhancements to the existing codebase and development workflow.
• Upgraded the technology stack to more recent versions (Java 6 to 8, Spring Framework 3 to 4).
• Developed an in-house tool to analyze service failures and identify their root causes.

Pet Projects

Intuitio (Intuition Training iOS App)

Education

Oracle Certification (2015)

Oracle Certified Associate, Java SE 8 Programmer

Belarusian State University of Informatics and Radioelectronics (2013 – 2019)

Master's Degree in Computer Science