Deep, expert-level knowledge of Microsoft SQL Server, including performance tuning, indexing strategies, and complex stored procedure development., Strong software engineering skills in TypeScript, specifically for developing and maintaining data access layers., Proven ability to analyze and optimize database performance in high-load, production environments., Experience in leading technical deep-dives with customers to diagnose data-related challenges in real-time., Understanding of database schema design, migration strategies, and data integrity principles., 4+ years of experience as a Data Engineer, Database Developer, or Backend Engineer with a strong focus on SQL., Exceptional analytical skills with a 'data-first' approach to problem-solving., Full English Proficiency., Work from the client’s office 2–3 days per week in Warsaw or Kraków., Experience with large-scale identity data (Active Directory/Entra ID).