Research Engineer, Applied Research

The role

The Research Engineer will tackle unsolved applied AI and ML problems. You will develop, fine-tune, evaluate, and deploy models to improve customer-facing AI agents.

What you will do

• Tackle unsolved applied AI and ML problems.
• Determine when to build specialized models or use external frontier intelligence.
• Turn ambiguous product and customer problems into machine learning problems.
• Develop, fine-tune, evaluate, and deploy models.
• Advance post-training work from supervised fine-tuning toward reinforcement learning.
• Build rigorous evaluations connecting model performance to real-world agent quality.
• Work with large-scale, proprietary datasets spanning text and audio.
• Collaborate across Sierra from experimentation through production deployment.

Required qualifications

• Strong experience building and deploying production machine learning and AI systems.
• Excellent judgment in framing product problems as ML tasks.
• Experience working deeply with data, experimentation, evaluation, and model iteration.
• A practical, evidence-driven approach to ML.
• Ability to operate with high agency and work across the stack.
• Alignment with Sierra’s values.
• A degree in computer science, machine learning, or a related field, or equivalent professional experience.

Nice to have

• Experience with supervised fine-tuning or reinforcement learning.
• Experience in search, ranking, recommendations, or advertising systems.
• Experience training and deploying language, speech, or multimodal models.
• Experience designing model evaluations tied to real-world product outcomes.
• Experience working with large-scale consumer datasets or high-volume ML products.
• Contributions to applied ML research or benchmarks.

Benefits

• Flexible (unlimited) paid time off
• Medical, dental, and vision benefits for you and your family
• Life insurance and disability benefits
• Retirement plan dependent on country of employment
• Parental leave
• Fertility and family building benefits
• Lunch, snacks, and coffee when working onsite
• Discretionary benefit stipend
• Free alphorn lessons
• Equity plans for eligible full-time employees

About the company

Sierra is a platform for customer-facing AI agents. It was co-founded by Bret Taylor and Clay Bavor.