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Research Engineer, Applied Research

SierraSan Francisco, CAEngineering
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Salary
Not listed
Job type
Full-time
Experience
Senior
Posted
5 Oct 2026
Status
Open · checked 7d ago

About this role

This role suits an applied machine learning professional with a background in building production systems who wants to work in a primarily in-person environment in San Francisco. The Research Engineer, Applied Research position at Sierra involves advancing the quality, speed, and cost efficiency of models powering customer-facing AI agents.

Role Overview

Sierra is seeking a Research Engineer, Applied Research for its team in San Francisco, CA. The role focuses on tackling unsolved applied artificial intelligence and machine learning problems, pushing boundaries in post-training, voice AI, and long-horizon task execution to support customer-facing AI agents.

Key Responsibilities

Tackle unsolved applied AI and ML problems by building agents that reason, adapt, and execute complex tasks.
Determine when to build specialized models versus using external frontier intelligence to balance quality, speed, and cost.
Turn ambiguous product and customer problems into well-framed machine learning tasks.
Develop, fine-tune, evaluate, and deploy models that enhance customer-facing AI agents.
Advance post-training initiatives moving from supervised fine-tuning to reinforcement learning and long-horizon optimization.
Build rigorous evaluations connecting model performance to real-world agent quality.
Work with large-scale, proprietary datasets spanning text and audio interactions.
Collaborate across the organization to take ideas from experimentation through production deployment.

Requirements

Strong experience building and deploying production machine learning and AI systems across areas like search, ranking, recommendations, advertising, language, and speech.
Excellent judgment in framing product problems as ML tasks and selecting effective approaches.
Experience working with data, experimentation, evaluation, and model iteration.
Practical, evidence-driven approach to machine learning with judgment on when modeling is necessary.
Ability to operate with high agency and work across the stack.
Alignment with company values including Craftsmanship, Customer Obsession, and Competitive Intensity.
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.
Background 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.

Skills and Tools

Machine Learning
Artificial Intelligence
Supervised Fine-Tuning
Reinforcement Learning
Post-Training
Voice AI
Multimodal Models
Language and Speech Models

Salary and Benefits

Flexible, unlimited paid time off
Medical, dental, and vision benefits for employees and families
Life insurance and disability benefits
Retirement plan dependent on country of employment
Parental leave
Fertility and family building benefits through Carrot
Onsite lunch, snacks, and coffee
Discretionary benefit stipend
Free alphorn lessons
Participation in equity plans for eligible full-time employees

About the Company

Sierra is a platform for customer-facing AI agents collaborating with global brands such as The GAP, Rocket Mortgage, SoFi, Sutter Health, and SoftBank. The company is primarily in-person and based in San Francisco, with growing offices across North America, Europe, and Asia. It is guided by values of Trust, Customer Obsession, Craftsmanship, Intensity, and Family, and was co-founded by Bret Taylor and Clay Bavor.

How to Apply

Candidates should apply on the official company careers page.

Skills and tech stack

Machine LearningAI AgentsLanguage ModelsSpeech ModelsMultimodal ModelsReinforcement LearningFine-tuning

Questions candidates ask

Where is the Research Engineer position located?

The role is primarily in-person and based in San Francisco, CA, with growing offices across North America, Europe, and Asia.

What kind of background is needed for this role?

Candidates need strong experience building and deploying production machine learning and AI systems, with backgrounds welcomed across applied ML such as search, ranking, recommendations, advertising, language, and speech, or a degree in computer science, machine learning, or a related field.

What does the Applied Research team focus on?

The team advances the quality, speed, and cost efficiency of the models powering Sierra agents across various tasks, spanning post-training open-weight models and voice AI.

What benefits are offered to full-time employees?

Benefits include flexible paid time off, medical, dental, and vision coverage, life and disability insurance, a retirement plan, parental leave, Carrot fertility benefits, onsite food and coffee, a discretionary benefit stipend, free alphorn lessons, and eligibility for equity plans.

Who co-founded Sierra?

Sierra was co-founded by Bret Taylor and Clay Bavor.

Ready to apply?

The application is on the official Sierra careers page.

Apply on company site