Jakub Karbowski developed foundational Participant Attributes Management for the Solvro/backend-eventownik repository, focusing on backend development and database design using TypeScript and SQL. He introduced database migrations to create participant_attributes and attributes tables, enabling the flexible association of custom attributes with participants and events. By defining attribute metadata such as name, slug, event, options, and type, Jakub established a robust data model that supports future event-level customization and richer participant data capture. His migration-first approach minimized runtime impact while laying the groundwork for attribute-driven workflows, segmentation, and reporting, demonstrating depth in designing scalable, analytics-ready backend systems.