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# C# .NET Core Backend Engineer - APIs & SQL | Remote

- **Company:** Client Server
- **Location:** Madrid, Spain (Remote available)
- **Contract:** Permanent contract
- **Skills:** Application Programming Interfaces (APIs), C Sharp (Programming Language), Client Server Models, Cloud Computing, Standard Sql, SQL Databases, .NET Core, Backend
- **Published:** October 18, 2026
- **Apply:** https://www.jobleads.com/es/job/c-net-core-backend-engineer-apis-sql-remote--madrid--edf8aa475e4df55c84319e3686b1d056b

## About the Role

You will split time between the Madrid office and remote work, with 2-3 days in-office and flexible days at home. The role requires strong C# and SQL skills, cloud experience, and English fluency.

## Description

Client Server Limited is seeking a senior Software Developer in Madrid to lead the rebuild of a major payments platform. You will work on C# .NET Core APIs, design scalable backend services, and own projects from design through production, while mentoring peers.

You will split time between the Madrid office and remote work, with 2-3 days in-office and flexible days at home. The role requires strong C# and SQL skills, cloud experience, and English fluency.