Senior Windows SDK Engineer - C#/.NET (m/f/x)

Senior Windows SDK Engineer - C#/.NET (m/f/x)

Department: osapiens Hub

Employment Type: Full Time

Location: Madrid

Reporting To: Head of Hub Engineering

Description

About osapiens

At osapiens, more than 550 talented minds unite around one mission: enabling sustainable growth for businesses worldwide. Founded in 2018 and headquartered in Mannheim, Germany, we have built the AI-driven osapiens HUB - a multi-tenant platform hosting 26 enterprise-grade solutions designed for cross-company collaboration, automation, and compliance. With offices across Europe and the US, we are shaping the future of scalable and secure business technology.

Your Team

Join our Mobile Core Framework team to build and evolve the Windows native layer of our mobile client SDK. You'll design and implement C#/.NET APIs that bridge native Windows capabilities to React Native for Windows, enabling app developers across the company to build powerful, performant applications for the Windows ecosystem.

Your Responsibilities

• Design, build, and maintain native Windows modules in C# that expose platform capabilities (offline sync, background tasks, device integrations) to React Native applications
• Own the React Native for Windows bridge layer, including native module architecture and XAML components
• Optimize SDK performance with focus on memory management, responsiveness, and startup time
• Stay current with Windows platform evolution (WinUI, Windows App SDK, .NET updates) and integrate relevant capabilities into the SDK
• Build and maintain automated test suites and CI/CD pipelines in Azure DevOps
• Collaborate with app development teams to understand their needs and provide excellent developer experience
• Contribute to SDK documentation and versioning strategy

Your Experience

• Strong proficiency in C# and .NET (6.0+)
• Experience with Universal Windows Platform (UWP) or Windows App SDK development
• Familiarity with React Native for Windows native module development (or willingness to learn quickly)
• Solid understanding of async/await patterns, threading, and performance optimization in .NET
• Experience with Visual Studio, MSBuild, and Windows application packaging
• English is our working language; fluency in written and spoken English is required

Nice to Have

• Experience building libraries, SDKs, or frameworks consumed by other developer
• Knowledge of TypeScript and React Native architecture
• Experience with XAML and WinUI
• Familiarity with CI/CD pipelines in Azure DevOps
• Experience with iOS (Swift) or Android (Java/Kotlin) development

Join us for this and more...

• A purpose-driven mission with and for global industry pioneers in tackling complex challenges
• Room for creativity through collaborative teamwork and an open communication culture
• Flexibility and team bonding with our hybrid work options
• Fuel for your growth journey, both personally and professionally
• Sustainable mobility options, promoting eco-friendly commuting solutions
• Fun team events and outings with our global teams
• Inspiring workspaces in Mannheim and beyond