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@QaraLabs

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RomanVassilchenko/README.md

Roman Vassilchenko

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Go backend engineer building high-load distributed systems, credit decision workflows, and production microservice platforms

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Professional Experience

Bereke Bank — Middle Backend Developer

Auto Loan Issuance Team / Unified Credit Pipeline Team · Sep 2025 - Present

Building unified credit decision infrastructure for retail lending at one of Kazakhstan's major banks.

  • Architecting and building the company's unified credit pipeline, standardizing loan issuance across products
  • Built numerous production integrations with government and financial services, including FCB, collateral registries, and identity verification
  • Designed fault-tolerant microservice architecture with strict latency SLA and event-driven communication via Kafka
  • Delivered collateral-backed auto-loan processing improvements, reducing issuance time from 40 to 15 minutes and helping increase application throughput by 3x
  • Built a corporate messenger alerting library and operational notifications for production workflows

Tech: Go PostgreSQL Redis Kafka Camunda BPMN Docker GraphQL REST Microservices CI/CD


Ozon — Junior Go Developer

Staff Team · Aug 2024 - Sep 2025

Built and scaled backend products for a large employee platform serving 10000-15000 DAU and 40000+ MAU.

  • Contributed to the design and decomposition of the Staff Portal monolith into microservices, optimizing core load by 20-25% within my domain
  • Built staff-lib, an internal Go library adopted across 30+ services
  • Designed office attendance and seat-reclamation logic for 60000+ employees
  • Developed ETL pipelines from internal survey platform to Vertica for self-service analytics
  • Built document generation infrastructure with configurable templates
  • Improved large-file and video preview workflows in internal cloud storage service

Tech: Go gRPC REST PostgreSQL ClickHouse Vertica Kafka Redis Grafana Prometheus Microservices


Ozon — Go Backend Intern / Junior Developer

Matrix Hiring Team · Dec 2023 - Aug 2024

Worked on a company-wide hiring platform covering the full flow from job posting to onboarding.

  • Optimized candidate ranking SQL queries with significant speedup under production load
  • Improved ElasticSearch filtering throughput by 2.5x
  • Built a gRPC notification service with Kafka-based sharding and delayed delivery
  • Created Grafana dashboards for hiring funnel monitoring and anomaly detection

Tech: Go gRPC REST PostgreSQL Redis ElasticSearch Kafka ClickHouse Grafana


Tech Stack

Go gRPC REST GraphQL ConnectRPC PostgreSQL Redis ClickHouse Vertica ElasticSearch MongoDB Neo4j Kafka Camunda BPMN Docker Kubernetes MinIO / S3 Protobuf Buf Prometheus Grafana GitHub Actions CI/CD Linux NixOS Python TypeScript


Featured Projects

Public Procurement Analytics Platform

Rule-based corruption risk detection platform for Kazakhstan's public procurement: 14.47 million contracts, 197 thousand buyers, 800 thousand suppliers, and 8 indicator algorithms operating without labeled data.

  • Produced 448 thousand risk flags across all 20 regions
  • Calibrated risk thresholds with government auditors
  • Used in real audit workflows and became the basis for an academic research paper

Stack: Go ConnectRPC PostgreSQL MinIO / S3 Kafka GraphQL Buf React TypeScript Docker


Staff Portal 2.0

Enterprise employee platform for 60000+ users

Monolith decomposition, shared backend infrastructure, document generation, and large-file workflows for a high-load internal platform.

Stack: Go gRPC PostgreSQL ClickHouse Vertica Kafka Redis Grafana


Matrix Hiring

Hiring platform from job posting to onboarding

Backend work on ranking, search, notifications, and observability for large-scale recruiting workflows.

Stack: Go gRPC PostgreSQL ElasticSearch Kafka ClickHouse Grafana


Education

B.Sc. Software Engineering — Astana IT University, Kazakhstan (2023 - 2025)

  • Backend, databases, and distributed systems focus
  • Previous studies: ITMO University, St. Petersburg (2021 - 2023)

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    Modular NixOS dotfiles with flakes, Home Manager, KDE Plasma, host templates, and optional private overlays

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