Principal Software Engineer

Security represents the most critical priorities for our customers in a world awash in digital threats, regulatory scrutiny, and estate complexity. Microsoft Security aspires to make the world a safer place for all. We want to reshape security and empower every user, customer, and developer with a security cloud that protects them with end to end, simplified solutions. The Microsoft Security organization accelerates Microsoft’s mission and bold ambitions to ensure that our company and industry is securing digital technology platforms, devices, and clouds in our customers’ heterogeneous environments, as well as ensuring the security of our own internal estate. 

Do you ever think about the code you didn’t write? Because most of it—you didn’t. Modern software is assembled, not authored. A single application depends on hundreds, often thousands, of open-source components written by people you’ll never meet—yet running with the same privileges as the code you carefully review and own. This is the software supply chain—and it has quietly become one of the most actively exploited attack surfaces in the world.

Become an integral member of the Microsoft Defender for Endpoint (MDE) Team. We’re looking for a Principal Software Engineer who wants to help build the foundational capabilities to defend it. In this role, you’ll work on detecting and stopping threats at the source—whether it’s a malicious npm package, a typosquatted dependency, or a compromised update—before it ever reaches a developer’s project or production environment.

You’ll operate at ecosystem scale, analyzing large volumes of code, understanding what it actually does (not just what it claims), tracing provenance and trust, and turning those signals into real-time protection within the tools developers already use. These are new primitives—many don’t exist yet—and you’ll help define and build them. This is greenfield work built natively across Microsoft’s ecosystem, with deep integration into GitHub, Visual Studio, Azure, and open-source platforms. You’ll be part of a team small enough that what you build ships quickly and has real impact. There are very few places where a single engineer can write code that protects millions of developers and the software they deliver to the world. Defender is one of them. If you love building, move fast, and want to work on a problem that truly matters—let’s talk.

Required Qualifications:

• Bachelor's Degree in Computer Science or related technical field AND 6+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python OR equivalent experience.
   

Other Requirements: 

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