Principal Software Engineer

Microsoft Advertising is seeking aPrincipalSoftware Engineerto join ourAds Engineering Platformteam and advance the core capabilities of our ad-serving infrastructure-the engine that powers advertising across Bing Search, MSN, Microsoft Start, and shopping experiences in the Edge browser. Our serving stack operates atmassive global scale, deliveringmillions of ad requests per secondthrough ageo-distributed, low-latency systemthat combineslarge-scaleGPU/CPU inference, real-time bidding, and intelligent ranking pipelines. This role focuses on advancing the performance, efficiency, and scalability of the next generation of model serving and inference platforms for Ads.As a senior technical leader, you'll design and optimizehigh-performance serving systems andGPUinference frameworksthat drive measurable latency improvements and cost efficiency across Microsoft's ad ecosystem. You'll work across the stack-from CUDA kernel tuning and NUMA-aware threading to large-scale distributed orchestration and model deployment for deep learning and LLM workloads. This is a rare opportunity to shape the architecture of one of the world's most advanced, mission-critical online serving platforms, collaborating with world-class engineers to deliver innovation at Internet scale.

Microsoft's mission is to empower every person and every organization on the planet to achieve more. As employees we come together with a growth mindset, innovate to empower others, and collaborate to realize our shared goals. Each day we build on our values of respect, integrity, and accountability to create a culture of inclusion where everyone can thrive at work and beyond.

Starting January 26, 2026, Microsoft AI (MAI) employees who live within a 50- mile commute of a designated Microsoft office in the U.S. or 25-mile commute of a non-U.S., country-specific location are expected to work from the office at least four days per week. This expectation is subject to local law and may vary by jurisdiction.

• Design and lead the development of large-scale, distributed online serving systems-including GPU-accelerated and CPU-based ranking/inference pipelines-to process millions of ad requests per second with ultra-low latency, high throughput, and solid reliability.
• Architect and optimizeend-to-end inference infrastructure, including model serving, batching/streaming, caching, scheduling, and resource orchestration across heterogeneous hardware (GPU, CPU, and memory tiers).
• Profile and optimize performanceacross the full stack-from CUDA kernels and GPU pipelines to CPU threads and OS-level scheduling-identifying bottlenecks, tuning latency tails, and improving cost efficiency through advanced profiling and instrumentation.
• Own live-site reliabilityas a DRI: design telemetry, alerting, and fault-tolerance mechanisms; drive rapid diagnosis and mitigation of performance regressions or outages in globally distributed systems.
• Collaborate and mentoracross teams-driving architecture reviews, enforcing engineering excellence, promoting system-level optimization practices, and mentoring others in deep debugging, profiling, and performance engineering.

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.

Preferred Qualifications:

• Master's Degree in Computer Science or related technical field AND 8+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python
  • OR Bachelor's Degree in Computer Science or related technical field AND 12+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python
  • OR equivalent experience.
• Industry experience inadvertising or search engine backend systems, such as large-scale ad ranking, real-time bidding (RTB), or relevance-serving infrastructure.
• Hands-on experience withreal-time data streaming systems(Kafka, Flink, Spark Streaming),feature-store integration, andmulti-region deploymentfor low-latency, globally distributed services.
• Familiarity withLLM inference optimization-model sharding, tensor/kv-cache parallelism, paged attention, continuous batching, quantization (AWQ/FP8), and hybrid CPU-GPU orchestration.
• Demonstrated success operating large-scale systems withSLA-based capacity forecasting, autoscaling, and performance telemetry; proven leadership in cross-functional architecture initiatives and technical mentorship.
• Passion for performance engineering, observability, and deep systems debugging, with a solid drive to push the limits of serving infrastructure for the next generation of ads and AI models.
• Deep expertise in GPU inference frameworkssuch asNVIDIA Triton Inference Server, CUDA, and TensorRT, including hands-on experience implementingcustom CUDA kernels, optimizing memory movement (H2D/D2H), overlapping compute and I/O, and maximizing GPU occupancy and kernel fusion for deep learning and LLM workloads.
• Solid understanding of model-serving trade-offs-batching vs. streaming, latency vs. throughput, quantization (FP16/BF16/INT8), dynamic batching, continuous model rollout, and adaptive inference scheduling across CPU/GPU tiers.
• Proven ability toprofile and optimize GPU and system workloads-including tensor/memory alignment, compute-memory balancing, embedding table management, parameter servers, hierarchical caching, and vectorized inference for transformer/LLM architectures.
• Expertise in low-level system and OS internals, includingmulti-threading, process scheduling, NUMA-aware memory allocation, lock-free data structures, context switching, I/O stack tuning (NVMe, RDMA), kernel bypass (DPDK, io_uring), and CPU/GPU affinity optimizationfor large-scale serving pipelines.

#MicrosoftAI

Software Engineering IC5 - The typical base pay range for this role across the U.S. is USD $139,900 - $274,800 per year. There is a different range applicable to specific work locations, within the San Francisco Bay area and New York City metropolitan area, and the base pay range for this role in those locations is USD $188,000 - $304,200 per year.

Certain roles may be eligible for benefits and other compensation. Find additional benefits and pay information here:
https://careers.microsoft.com/us/en/us-corporate-pay

This position will be open for a minimum of 5 days, with applications accepted on an ongoing basis until the position is filled.

Microsoft is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to age, ancestry, citizenship, color, family or medical care leave, gender identity or expression, genetic information, immigration status, marital status, medical condition, national origin, physical or mental disability, political affiliation, protected veteran or military status, race, ethnicity, religion, sex (including pregnancy), sexual orientation, or any other characteristic protected by applicable local laws, regulations and ordinances. If you need assistance with religious accommodations and/or a reasonable accommodation due to a disability during the application process, read more about requesting accommodations.