About Nebius: Nebius is leading a new era in cloud infrastructure for the global AI economy. We are building a full-stack AI cloud platform that supports developers and enterprises from data and model training through to production deployment, without the cost and complexity of building large in-house AI/ML infrastructure. Built by engineers, for engineers. From large-scale GPU orchestration to inference optimization, we own the hard problems across compute, storage, networking and applied AI. Listed on Nasdaq (NBIS) and headquartered in Amsterdam, we have a global footprint with R&D hubs across Europe, the UK, North America and Israel. Our team of 1,500+ includes hundreds of engineers with deep expertise across hardware, software and AI R&D. The role This position sits within Nebius Token Factory, our serverless platform for running and customizing open-source LLMs in production. Token Factory allows for serverless inference and fine-tuning (LoRA, full FT, RFT) backed by in-house optimizations like custom speculative decoding, quantization, cache-aware routing and dedicated endpoints. Customers come to us to move from prototype to scaled production without the cost and complexity of building and tuning their own inference stack. We're looking for a Principal ML Solutions Architect to act as the most senior technical authority for customers leveraging Token Factory's serverless inference and fine-tuning platforms. Beyond designing and implementing optimized inference and fine-tuning workflows, you will set technical direction across our largest and most strategic accounts, own the hardest performance and quality problems end to end, mentor other Solutions Architects, and serve as a primary technical voice shaping the platform roadmap with backend, product, and research teams. You’re welcome to work remotely from the United States. Your responsibilities will include:  • Own the most complex, highest-stakes customer engagements from architecture through production across multiple modalities, driving measurable business value • Optimize LLM inference at the framework and hardware level and codify the resulting best practices into reusable playbooks for the team • Lead supervised and reinforcement fine-tuning efforts to maximize model quality • Design and implement production-ready LLM solutions using Token Factory's inference services • Provide deep technical expertise in prompt engineering, RAG architectures, model selection, and cost/performance trade-offs at scale • Partner closely with product, engineering and research to surface customer needs, prototype platform features, and directly influence the roadmap • Guide customers from PoC to production with a focus on performance, reliability, and cost efficiency — and define the standards by which the team does so • Mentor Senior and mid-level Solutions Architects; raise the technical bar of the team through review, enablement, and knowledge sharing • Represent Token Factory externally through talks, blog posts, and conferences We expect you to have:  • 8+ years of experience in ML/AI systems, with at least 4 years focused on LLMs and generative AI • Demonstrated technical leadership: owning ambiguous, high-impact problems end to end and influencing decisions across teams and customers • Expert knowledge of the LLM ecosystem: model architectures, fine-tuning approaches, and inference internals • Deep, hands-on command of inference optimization: quantization, KV-cache management, batching, routing, etc. • Hands-on experience with: • Running LLMs in production at scale: deploying, operating, and debugging inference workloads down to the framework level • LLM fine-tuning, including SFT/LoRA and data preparation/curation; experience with RL-based fine-tuning • LLM evaluation: building task-specific benchmarks and offline/online eval pipelines, including LLM-as-a-judge setups • Inference frameworks and libraries (vLLM, SGLang, TensorRT-LLM), including the ability to read, modify, and contribute to their internals • Deploying LLM-powered applications using APIs from OpenAI, Anthropic, or open-source models • Strong Python programming skills • Excellent communication skills, with the ability to clearly explain technical concepts to diverse audiences, from engineers to executives It would be an added bonus if you have:  • Contributions or maintainership in major OSS inference/ML projects (vLLM, SGLang, TensorRT-LLM) • Published research, conference talks, or widely-read technical writing in the LLM/serving space • Deep work with multimodal AI models (vision-language, speech) • Proficiency with DevOps tooling (Docker, Kubernetes) and infrastructure-as-code • Experience building or owning internal tooling/automation for ML workflows at scale Preferred technical stack: • Programming Languages: Python • ML Frameworks and Libraries: vLLM, TensorRT-LLM, SGLang, Transformers, OpenAI/Anthropic SDKs • MLOps and DevOps tools: Kubernetes (K8s), Docker, Git • Cloud Platforms: AWS (SageMaker, Bedrock), GCP (Vertex AI), Azure (Azure ML) Key Employee Benefits: • Health Insurance: 100% company-paid medical, dental, and vision coverage for employees and families. • 401(k) Plan: Up to 4% company match with immediate vesting. • Parental Leave: 20 weeks paid for primary caregivers, 12 weeks for secondary caregivers. • Remote Work Reimbursement: Up to $85/month for mobile and internet. • Disability & Life Insurance: Company-paid short-term, long-term, and life insurance coverage. #LN-DK1 Pay Transparency We offer competitive compensation and benefits packages. Actual compensation will be determined based on job-related factors, including experience, skills, qualifications, the level at which the candidate is hired, and geographic location, consistent with applicable law. Base Compensation Range $208,000—$261,000 USD Benefits & Perks: • Competitive compensation • Career growth and learning opportunities • Flexibility and ownership • Collaborative and innovative culture • Opportunity to work on impactful AI projects • International environment and talented teams What's it like to work at Nebius: Fast moving - Bold thinking - Constant growth - Meaningful impact - Trust and real ownership - Opportunity to shape the future of AI  Equal Opportunity Statement: Nebius is an equal opportunity employer. We are committed to fostering an inclusive and diverse workplace and to providing equal employment opportunities in all aspects of employment. We do not discriminate on the basis of race, color, religion, sex (including pregnancy), national origin, ancestry, age, disability, genetic information, marital status, veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by applicable law. Applicants must be authorized to work in the country in which they apply and will be required to provide proof of employment eligibility as a condition of hire.  If you need accommodations during the application process, please let us know.