Cortance

Senior Java engineer

Oleksandr K

Information

Available hours \ week
40 h/w
Seniority level
Senior
Years of experience
15 yrs.
Location
Poland, Kraków
Nationality
Ukraine
Timezone
-

Languages

English
Upper-Intermediate (B2)

About

Oleksandr is a Senior Java Engineer with a strong focus on backend development, bringing 15 years of experience in building scalable applications. He extensively uses Spring Framework, Spring Boot, and Java to design and implement robust system components in various domains, including fintech, data analytics, and management. His proficiency spans multiple databases such as MongoDB and PostgreSQL, enabling efficient data handling and storage solutions. Oleksandr has also worked with cloud platforms like AWS and GCP, integrating them into application architectures. His skills in Kotlin and JavaScript further enhance his versatility in developing modern applications that meet complex requirements. In addition to technical expertise, he has taken on team leadership roles, mentoring junior engineers and ensuring adherence to best practices through code reviews. His experience includes handling challenges related to data integrity, compliance requirements, and system performance across diverse industries, etc. Oleksandr holds a Specialist’s degree in Physics and Computer Science.

Main technologies

Additional skills

Experience

Identity and Access Management (IAM) system

Senior Software Engineer

About the Project

Identity and Access Management (IAM) system used for user authentication and authorization across multiple client systems. The service supports the integration of various authentication, authorization, and access rights management flows for end users. It is used daily by millions of users across EU countries.

  • Management

Responsibilities

- Designed and implemented core system components; - Conducted code reviews and mentored junior team members; - Maintained the legacy version of the system and resolved end-user issues; - Introduced and applied Clean Architecture principles in the design and implementation of system components, improving maintainability and scalability; - Developed custom Keycloak plugins; - Designed and implemented an event generation, transmission, aggregation, and analytics subsystem for operational monitoring; - Built and maintained data migration pipelines for millions of users transitioning from the legacy product version to the latest release.

A data protection platform

Senior Software Engineer

About the Project

Cloud Backup System - a data protection platform designed to back up and restore data from third-party cloud services such as SharePoint, OneDrive, Google Drive, and Gmail. The system supports document versioning, full-text indexing, and content search, enabling reliable recovery and auditability. It complies with strict regulatory requirements including GDPR and HIPAA.

  • Data Analytics

Responsibilities

- Designed and evolved the architecture of core system components for scalable data ingestion and storage; - Implemented backup and restore pipelines for multiple third-party cloud providers, ensuring data consistency and fault tolerance; - Maintained and enhanced legacy components, improving system stability and performance; - Introduced and implemented new features including document versioning, indexing, and content-based search capabilities; - Integrated the platform with external cloud provider APIs (Google Workspace, Microsoft 365), handling authentication, rate limits, and data synchronization challenges; - Ensured compliance with GDPR and HIPAA requirements, including secure data handling, access control, and audit logging.

Taskize

Senior Software Engineer

About the Project

Taskize – a task management and workflow system tailored for the banking sector, similar to Jira but adapted to financial domain requirements. The platform enables users to create, track, and manage tasks while integrating with existing banking systems and workflows.

  • Fintech
  • Banking

Responsibilities

- Designed architecture for new system components aligned with banking domain requirements and compliance constraints; - Developed integration solutions between Taskize and existing enterprise banking systems, ensuring secure and reliable data exchange; - Contributed to the evolution of the platform architecture to support scalability and extensibility; - Participated in defining communication patterns between services, including asynchronous workflows and notification mechanisms; - Integrated email notification functionality using Amazon SES for task updates and workflow events; - Ensured high code quality through code reviews and adherence to best development practices;

Skills & technologies

Cashjoy

Senior Software Engineer

About the Project

Cashjoy – a gaming service provider platform that integrates with external gaming portals via REST APIs, enabling seamless access to games for end users without exposing the underlying provider. The system operates in an isolated cloud environment and supports regulatory compliance for multiple jurisdictions.

  • Gambling
  • GameDev

Responsibilities

- Designed and implemented system architecture for a scalable and isolated gaming service provider platform; - Developed core backend services using Kotlin and Spring Boot, focusing on performance and reliability; - Implemented REST API integrations with external gaming portals, ensuring seamless user experience and secure communication; - Integrated the platform with existing portal systems, handling authentication, session management, and data synchronization; - Maintained and adapted legacy components to meet evolving business and regulatory requirements; - Led efforts to prepare the system for certification in regulated markets, ensuring compliance with country-specific standards.