What you'll do- 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.
What you'll bring- Strong experience building and deploying production machine learning and AI systems. We welcome backgrounds across applied ML, including search, ranking, recommendations, advertising, language, and speech.
- Excellent judgment in framing product problems as ML tasks and selecting the simplest & most effective approach.
- Experience working deeply with data, experimentation, evaluation, and model iteration.
- A practical, evidence-driven approach to ML, with strong judgement around when a problem calls for modeling and when a simpler solution will deliver the best outcome.
- The ability to operate with high agency and work across the stack when needed to deliver an outcome.
- Alignment with Sierra's values, including Craftsmanship, Customer Obsession, and Competitive Intensity.
- A degree in computer science, machine learning, or a related field, or equivalent professional experience.
Even better...- 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.
Our values- Trust: We build trust with our customers with our accountability, empathy, quality, and responsiveness. We build trust in AI by making it more accessible, safe, and useful. We build trust with each other by showing up for each other professionally and personally, creating an environment that enables all of us to do our best work.
- Customer Obsession: We deeply understand our customers' business goals and relentlessly focus on driving outcomes, not just technical milestones. Everyone at the company knows and spends time with our customers. When our customer is having an issue, we drop everything and fix it.
- Craftsmanship: We get the details right, from the words on the page to the system architecture. We have good taste. When we notice something isn't right, we take the time to fix it. We are proud of the products we produce. We continuously self-reflect to continuously self-improve.
- Intensity: We know we don't have the luxury of patience. We play to win. We care about our product being the best, and when it isn't, we fix it. When we fail, we talk about it openly and without blame so we succeed the next time.
- Family: We know that balance and intensity are compatible, and we model it in our actions and processes. We are the best technology company for parents. We support and respect each other and celebrate each other's personal and professional achievements.
What we offerWe want our benefits to reflect our values and offer the following to full-time employees:
- 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, as well as delicious snacks and coffee to keep you energized
- Discretionary benefit stipend giving people the ability to spend where it matters most
- Free alphorn lessons
These benefits are further detailed in Sierra's policies, may vary by region, and are subject to change at any time, consistent with the terms of any applicable compensation or benefits plans. Eligible full-time employees can participate in Sierra's equity plans subject to the terms of the applicable plans and policies.
