Principal Applied Scientist, Agentic AI

Principal Applied Scientist Focused On Rl Post-Training

Zillow is investing deeply in next-generation AI and machine learning to power intelligent experiences across our products, helping customers and partners make better decisions in a complex, real-world domain. Our team brings together Applied Scientists, ML engineers, and Software engineers who own the full lifecycle of large-scale systems that combine modern foundation models with applied ML—from data and modeling through evaluation and deployment. We collaborate closely with platform, product, and operations partners in a fast-moving, remote-first environment where experimentation, learning, and shipping are core to how we work.

As a Principal Applied Scientist focused on RL post-training, you will lead the design and deployment of learning systems that shape how our models behave in real products. You will own the technical direction and strategy for post-training and adaptation of large models to align behavior with user value, safety, and business objectives. This is a high-impact principal IC role with broad influence across Zillow, working closely with senior leadership to ensure our investments translate into safer, more capable, and more trusted AI-powered experiences.

You will get to:

• Lead the technical direction and strategy for RL post-training of production models, partnering with other scientists, engineers, and product leaders to align models with customer and business needs.
• Design and implement post-training pipelines that combine techniques such as supervised fine-tuning on curated demonstrations, preference modeling and pairwise ranking, and RL-based alignment approaches like RLHF, RLAIF, or DPO for multi-objective optimization.
• Develop reward models and objective formulations that balance constraints such as helpfulness, safety, fairness, compliance, and customer satisfaction, and iterate on them using human and AI feedback at scale through online and batch adaptation loops with strong guardrails.
• Translate conversational logs, behavioral signals, and structured attributes into training, reward, and evaluation signals for post-training and reinforcement learning, turning heterogeneous data into actionable supervision.
• Partner with model and platform teams to improve the efficiency and robustness of training and evaluation, including off-policy evaluation, replay strategies, controlled rollouts, and metrics and evaluation frameworks such as win-rates versus baselines, safety and quality metrics, and expert-review programs.
• Mentor applied scientists and engineers, raising the technical bar in RL, post-training, and evaluation, and contributing to the broader AI roadmap at Zillow through thought leadership and guidance.
• When appropriate, represent Zillow's work externally through talks, publications, or open-source contributions.

This role has been categorized as a Remote position. "Remote" employees do not have a permanent corporate office workplace and, instead, work from a physical location of their choice, which must be identified to the Company. U.S. employees may live in any of the 50 United States, with limited exceptions. In California, Connecticut, Maryland, Massachusetts, New Jersey, New York, Washington state, and Washington DC the standard base pay range for this role is $191,300.00 - $305,700.00 annually. This base pay range is specific to these locations and may not be applicable to other locations. In Colorado, Hawaii, Illinois, Minnesota, Nevada, Ohio, Rhode Island, and Vermont the standard base pay range for this role is $181,800.00 - $290,400.00 annually. The base pay range is specific to these locations and may not be applicable to other locations. In addition to a competitive base salary this position is also eligible for equity awards based on factors such as experience, performance and location. Actual amounts will vary depending on experience, performance and location. Employees in this role will not be paid below the salary threshold for exempt employees in the state where they reside.

You are an applied scientist who is excited to use reinforcement learning and post-training methods to shape how AI systems behave in complex, high-judgment settings, and you are comfortable owning ambiguous problems end-to-end—from framing the objective and data strategy to shipping models into production and measuring their impact.

You have a PhD or equivalent experience in Computer Science, Electrical Engineering, Statistics, or a related field, with emphasis in areas such as reinforcement learning, bandits, large language models, or applied machine learning.

You have strong, current expertise in post-training techniques (such as supervised fine-tuning, DPO, RLHF/RLAIF, preference modeling, and multi-objective optimization), in evaluation and monitoring of aligned models (including win-rate experiments, human and AI feedback loops, long-horizon evaluation, and safety or guardrail metrics), and in modern transformer-based models and tooling such as LLMs, multimodal models, vector search, and orchestration frameworks.

You have experience working with cross-functional partners (for example, engineering, product, design, operations, legal, and compliance) in domains where safety, trust, or regulation matter, such as marketplaces, finance, healthcare, or other high-stakes verticals.

You demonstrate technical leadership and mentorship, helping senior engineers and scientists grow, creating clarity amid ambiguity, and driving alignment across teams, and you communicate complex technical ideas clearly to both expert and non-expert audiences in writing and verbally.

Here at Zillow, we value the experience and perspective of candidates with non-traditional backgrounds. We encourage you to apply if you have transferable skills or related experiences.

At Zillow, we're reimagining how people move—through the real estate market and through their careers. As the most-visited real estate platform in the U.S., we help customers navigate buying, selling, financing and renting with greater ease and confidence. Whether you're working in tech, sales, operations, or design, you'll be part of a company that's reshaping an industry and helping more people make home a reality.

Zillow is honored to be recognized among the best workplaces in the country. Zillow was named one of FORTUNE 100 Best Companies to Work For® in 2025, and included on the PEOPLE Companies That Care® 2025 list, reflecting our commitment to creating an innovative, inclusive, and engaging culture where employees are empowered to grow.

No matter where you sit in the organization, your work will help drive innovation, support our customers, and move the industry—and your career—forward, together.

Zillow Group is an equal opportunity employer committed to fostering an inclusive, innovative environment with the best employees. We are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity or Veteran status. If you have a disability or special need that requires accommodation, please contact your recruiter directly.

Qualified applicants with arrest or conviction records will be considered for employment in accordance with applicable state and local law.

Los Angeles County applicants: Job duties for this position include: work safely and cooperatively with other employees, supervisors, and staff; adhere to standards of excellence despite stressful conditions; communicate effectively and respectfully with employees, supervisors, and staff to ensure exceptional customer service; and follow all federal, state, and local laws and Company policies. Criminal history may have a direct, adverse, and negative relationship with some of the material job duties of this position. These include the duties and responsibilities listed above, as well as the abilities to adhere to company policies, exercise sound judgment, effectively manage stress and work safely and respectfully with others, exhibit trustworthiness and professionalism, and safeguard business operations and the Company's reputation. Pursuant to the Los Angeles County Fair Chance Ordinance, we will consider for employment qualified applicants with arrest and conviction records.