Research Engineer, Applied Research
San Francisco, CAFull-timePosted 2w ago
About the role
Applied Research team advances model quality, speed, and cost efficiency for Sierra’s customer-facing AI agents, spanning post-training open-weight models, voice AI, and long-horizon task execution, turning research breakthroughs into production systems.
Responsibilities
- Tackle unsolved applied AI and ML problems. Pushing the boundaries of post-training, voice AI, and long-horizon task execution, building agents that can reason, adapt, and reliably carry out complex tasks for customers.
- Determine when to build specialized models and when to use externally provided frontier intelligence, balancing quality, speed, and cost to deliver customer value.
- Turn ambiguous product and customer problems into well-framed machine learning problems.
- Develop, fine-tune, evaluate, and deploy models that improve Sierra’s customer-facing AI agents.
- Advance our post-training work, from supervised fine-tuning toward reinforcement learning and long-horizon optimization.
- Build rigorous evaluations that connect model performance to real-world agent quality.
- Work with large-scale, proprietary datasets spanning text and audio interactions.
- Collaborate across Sierra while taking ideas from experimentation through production deployment and customer impact.
Qualifications
- Strong experience building and deploying production machine learning and AI systems.
- Experience across applied ML including search, ranking, recommendations, advertising, language, and speech.
- Excellent judgment in framing product problems as ML tasks and selecting effective approaches.
- Experience with data, experimentation, evaluation, and model iteration.
- Practical, evidence-driven approach to ML with judgement on modeling vs simpler solutions.
- Ability to operate with high agency and work across the stack to deliver outcomes.
- Alignment with Sierra’s values (Craftsmanship, Customer Obsession, Competitive Intensity).
- A degree in computer science, machine learning, or related field, or equivalent professional experience.
Skills
Required:Production machine learning systemsData analysis and experimentation
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 through Carrot
- Lunch, snacks, and coffee
- Discretionary benefit stipend
- Free alphorn lessons
Last updated Oct 7, 2026. Interested? Apply on the company site.
About Sierra
Better customer experiences. Built on Sierra.
Sierra helps businesses build better, more human customer experiences with AI.
AICustomer ExperienceCustomer SupportVoiceai-agents-and-applicationsorchestrationvoice-ai-stackwing-list-2026
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