Senior .NET / SQL Developer

O projekcie: About the role  We are looking for an experienced developer to join us in one of two ongoing projects within ista:  - Project A – .NET-focused  Development and maintenance of a work planning web application used by hundreds of users.  - Project B – SQL / Data-focused  Supporting and evolving a data-heavy system with strong emphasis on SQL Server querying, performance, and operational stability.  👉 One role, one recruitment process – the project assignment will depend on your strengths and experience.  Tech Stack  - Backend: .NET, .NET Core, C#  - Frontend: JavaScript / TypeScript, HTML, CSS (project-dependent)  - Databases: SQL Server (T-SQL, Stored Procedures)  - Tools & Processes: Git, CI/CD, Agile/Scrum, REST APIs  - Other: Legacy systems, code quality tools, testing frameworks Wymagania: Must-have  - 5+ years of professional experience as a developer - Very strong SQL Server skills (T-SQL, performance optimisation) - Solid experience in .NET / C# or strong motivation to deepen it - Experience with web applications - Analytical, solution-oriented mindset - Strong communication skills and team attitude - English B2+ - Openness to working in an international environment Nice to have  - SSIS (deployment, maintenance, package creation) - BI / Data Warehousing experience - Experience with legacy systems - Knowledge of frontend frameworks - Familiarity with CI/CD pipelines Codzienne zadania: - Depending on the project, you will: - Project A – .NET-oriented - Implement new features in a web application - Participate in the full development lifecycle (analysis → design → implementation) - Maintain and refactor legacy code - Ensure high code quality and alignment with standards - Collaborate closely with other developers (incl. .NET & PHP teams) - Project B – SQL-oriented - Write advanced ad-hoc T-SQL queries - Create, deploy and optimize stored procedures - Perform performance tuning and query optimisation - Support day-to-day SQL Server operations: user creation, permissions, SQL Server Agent jobs - Work with large, complex databases (100+ tables / procedures)