Senior Machine Learning Scientist

Job Description
Zendesk's people have one goal in mind: to make Customer Experience better. Our products help more than 125,000 global brands (AirBnb, Uber, JetBrains, Slack, among others) make their billions of customers happy, every day.

Our team is dedicated to providing a state-of-the-art retrieval-augmented generation (RAG) platform across multiple channels; including customer service bots, email and search. In collaboration with Software and ML Engineers, we deliver high-quality AI products leveraging the latest tools and techniques, and serve them at a scale that most companies can only dream of. We're passionate about empowering end-users to quickly find answers to their questions, and helping our customers make the most of their knowledge base.

We're looking for a Senior ML Scientist to join our team. You will collaborate closely with engineers, product managers, and cross-functional teams to translate research into solutions directly impacting millions of support interactions. You will play a key role in levelling up the RAG platform powering Zendesk

What you'll be doing

• Research, prototype, and develop state-of-the-art NLP/ML models for use cases to drive automated resolutions for end-user issues.
• Design and execute rigorous experiments and evaluations (offline/online, A/B) to improve model accuracy and robustness.
• Improve prompts and hyperparameters to optimize our state-of-the-art retrieval and generative capabilities
• Work closely with ML Engineers to productionize ML solutions—including data pipelines, scalable model serving, and monitoring.
• Analyze large, multi-lingual customer interaction datasets to uncover insights and power new solutions.
• Participate in technical reviews and share knowledge of underlying ML methodologies and best practices.
• Present your work to a multi-disciplinary, global audience.
• Stay up to date with recent literature in Machine Learning and Natural Language Processing (NLP) and share knowledge internally.
• Champion initiatives to improve the quality and robustness of Zendesk AI capabilities.
• Mentor junior scientists and help grow the ML research culture.

Key challenges / use cases

• How do we enrich customer service conversations with accurate language detection and task classification, efficient retrieval and real-time conversation generation, to enable proactive customer engagement and optimal resolution?
• How can we automate all customer service interactions as much as possible with omni-channel bots with a knowledge base?
• How do we automate large-scale A/B testing and model evaluation (online and offline) to continually iterate and improve our RAG tools?
• What novel approaches or architectures (e.g., retrieval-augmented generation, agentic, few-shot/fine-tuning strategies) can extend our conversational AI platforms to unlock new customer support use cases and modalities?
• How do we efficiently operationalize, monitor, and update large-scale (LLM/ML) models in dynamic, high-throughput production settings, ensuring model health, drift detection, and continuous learning?
• How do we combine signals from conversation context, customer history, and external data to improve prediction and decision accuracy across our ML services?
• What are the emerging advancements in ML/AI research (e.g., large language models, efficient adaptation, re-ranking, retrieval, or explainable AI) that should be incorporated into Zendesk's customer experience ecosystem?
• How can we bridge the gap between cutting-edge research and impactful product features, rapidly validating ideas in production and quantifying their real-world business value?
• And many more

What you bring to the role

• MSc degree (PhD preferred) in computer science, electrical engineering, math, or related areas.
• Deep knowledge of ML theory, algorithms, and modern NLP/LLM techniques.
• Demonstrated ability to conduct independent research and deliver production-grade ML solutions.
• Strong coding skills in Python; experience with ML frameworks (preferably PyTorch).
• Experience with large-scale experimentation (e.g., A/B testing), data analysis, and performance tracking.
• Strong collaboration and communication abilities.
• Be pragmatic and results oriented.

What our tech stack looks like

• Our code is largely written in Python, with some parts in Ruby
• Our platform is built on AWS
• Our machine learning models rely on PyTorch
• Our ML pipelines use AWS Batch and MetaFlow
• Data is stored in RDS MySQL, Redis, S3, ElasticSearch, Kafka, and Athena
• Services are deployed to Kubernetes using Docker, with Kafka for stream processing
• Infrastructure health is monitored using Datadog and Sentry

What we offer

• Team of passionate people who love what they do
• Exciting opportunity to work with LLMs and RAG (retrieval augmented generation), rapidly evolving fields in AI
• Ownership of the product features at scale, making a significant impact for millions of customers
• Opportunity to learn and grow
• Possibility to specialise in areas such as security, performance, and reliability
• and everything you need to be effective and maintain work-life balance
• Flexible working hours
• Professional development funds
• Comfortable office and a remote-friendly environment

About Zendesk
Zendesk builds software for better customer relationships. It empowers organizations to improve customer engagement and better understand their customers. Zendesk products are easy to use and implement. They give organizations the flexibility to move quickly, focus on innovation, and scale with their growth.

More than 100,000 paid customer accounts in over 150 countries and territories use Zendesk products. Based in San Francisco, Zendesk has operations in the United States, Europe, Asia, Australia, and South America.

Interested in knowing what we do in the community? Check out the Zendesk Neighbor Foundation to learn more about how we engage with, and provide support to, our local communities.

Zendesk is an equal opportunity employer, and we're proud of our ongoing efforts to foster diversity & inclusion in the workplace. Individuals seeking employment at Zendesk are considered without regard to race, color, religion, national origin, age, sex, gender, gender identity, gender expression, sexual orientation, marital status, medical condition, ancestry, physical or mental disability, military or veteran status, or any other characteristic protected by applicable law.

By submitting your application, you agree that Zendesk may collect your personal data for recruiting, global organization planning, and related purposes. Zendesk's Candidate Privacy Notice explains what personal information Zendesk may process, where Zendesk may process your personal information, its purposes for processing your personal information, and the rights you can exercise over Zendesk's use of your personal information.

Hybrid: In this role, our hybrid experience is designed at the team level to give you a rich onsite experience packed with connection, collaboration, learning, and celebration - while also giving you flexibility to work remotely for part of the week. This role must attend our local office for part of the week. The specific in-office schedule is to be determined by the hiring manager.

The Intelligent Heart Of Customer Experience
Zendesk software was built to bring a sense of calm to the chaotic world of customer service. Today we power billions of conversations with brands you know and love.

Zendesk believes in offering our people a fulfilling and inclusive experience. Our hybrid way of working, enables us to purposefully come together in person, at one of our many Zendesk offices around the world, to connect, collaborate and learn whilst also giving our people the flexibility to work remotely for part of the week.

Zendesk is an equal opportunity employer, and we're proud of our ongoing efforts to foster global diversity, equity, & inclusion in the workplace. Individuals seeking employment and employees at Zendesk are considered without regard to race, color, religion, national origin, age, sex, gender, gender identity, gender expression, sexual orientation, marital status, medical condition, ancestry, disability, military or veteran status, or any other characteristic protected by applicable law. We are an AA/EEO/Veterans/Disabled employer. If you are based in the United States and would like more information about your EEO rights under the law, please click here.

Zendesk endeavors to make reasonable accommodations for applicants with disabilities and disabled veterans pursuant to applicable federal and state law. If you are an individual with a disability and require a reasonable accommodation to submit this application, complete any pre-employment testing, or otherwise participate in the employee selection process, please send an e-mail to with your specific accommodation request.