Principal Full-Stack Data Scientist - Recommendation Algorithms

About Stitch Fix, Inc. Stitch Fix (NASDAQ: SFIX) is the leading online personal styling service that helps people discover the styles they will love that fit perfectly so they always look - and feel - their best. Few things are more personal than getting dressed, but finding clothing that fits and looks great can be a challenge. Stitch Fix solves that problem. By pairing expert stylists with best-in-class AI and recommendation algorithms, the company leverages its assortment of exclusive and national brands to meet each client's individual tastes and needs, making it convenient for clients to express their personal style without having to spend hours in stores or sifting through endless choices online. Stitch Fix, which was founded in 2011, is headquartered in San Francisco. About the Team Stitch Fix is redefining retail by blending the art of fashion with the science of machine learning. Throughout the company's history, the Client Experience Algorithms Organization has been a key source of our innovation and competitive differentiation. We build the tools that power personal style, combining best-in-class models with expert human judgment. We foster a culture of ownership where Data Scientists manage the full lifecycle of their work, from research to model deployment. You’ll use multidisciplinary tools to solve complex problems in a data-rich environment, directly influencing how millions of clients discover what they love. The Recommendation Algorithms team is building the future of personalized apparel shopping by thoughtfully combining algorithms with product innovation. A key area of focus is the continued improvement of the quality of recommended assortments along various dimensions, including seasonality, diversity, and freshness. A secondary area is the ability to deliver high-quality recommendations in real time to engage and delight new clients and therefore expand our total addressable market  About the Role This role will lead the development of our outfit completion models. These models combine client preferences, stylist expertise, and machine learning to inspire and guide client discovery through personalized and cohesive outfits. A key area of focus is improving the quality and relevance of generated outfits across dimensions such as cohesiveness, diversity, and contextual awareness (e.g., occasion, seasonality, and trendiness). This role will also drive innovation in how these models are trained, evaluated, and served in real-time, ensuring a seamless and engaging client experience. You're excited about this opportunity because you will… Lead the technical direction and development of our outfit completion models, a critical component of the Stitch Fix client experience Drive end-to-end model development, from problem formulation and research to production deployment and iteration Design and implement state-of-the-art machine learning models (including deep learning approaches in PyTorch) to model relationships between items and generate high-quality outfits Mentor and guide other data scientists on the team, raising the bar for modeling, experimentation, and engineering excellence Own and evolve experimentation strategies, defining success metrics and translating results into clear business impact Partner cross-functionally with Product, Engineering, and Design to shape the roadmap for outfit-based experiences across StitchFix.com Tackle ambiguous, high-impact problems and bring structure, clarity, and technical leadership to drive solutions forward Leverage rich, multi-modal datasets spanning client behavior, merchandise attributes, and stylist inputs to power innovative recommendations We’re excited about you because… You have 5+ years of experience building and deploying machine learning models, including deep learning models in frameworks such as PyTorch You have strong experience with recommendation systems, ranking, or related domains (e.g., retrieval, embeddings, or generative modeling) You have demonstrated technical leadership, including mentoring other ICs, leading projects, or setting modeling direction You are comfortable owning ambiguous problem spaces and driving projects from concept to production You have deep experience with experimentation and causal inference, and can connect model improvements to business outcomes You are fluent in SQL and experienced working with large-scale datasets You are proficient in Python and have experience building production-ready data science systems You are an effective communicator who can influence cross-functional partners and align teams around a shared vision You are curious, pragmatic, and motivated to continuously raise the bar for both yourself and your team Why you'll love working at Stitch Fix... We are a group of bright, kind people who are motivated by challenge. We value integrity, innovation and trust. You’ll bring these characteristics to life in everything you do at St