Principal Machine Learning Engineer
Waltham · USD 192,500-302,500 · Full-time · Remote · Posted Sep 21, 2026
At a glance
- Employment
- Full-time
- Workplace
- Remote
- Location
- Waltham
- Salary
- USD 192,500-302,500 · OTE
About ZoomInfo
- ZoomInfo (NASDAQ: GTM) is the Go-To-Market Intelligence Platform that empowers businesses to grow faster with AI-ready insights, trusted data, and advanced automation. Its solutions provide more than 35,000 companies worldwide with a complete view of their customers, making every seller their best seller.
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- ZoomInfo is proud to be an equal opportunity employer, hiring based on qualifications, merit, and business needs, and does not discriminate based on protected status. We welcome all applicants and are committed to providing equal employment opportunities regardless of sex, race, age, color, national origin, sexual orientation, gender identity, marital status, disability status, religion, protected military or veteran status, medical condition, or any other characteristic protected by applicable law. We also consider qualified candidates with criminal histories in accordance with legal requirements.
- For Massachusetts Applicants: It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability. ZoomInfo does not administer lie detector tests to applicants in any location.
About the role
- The Principal Machine Learning Engineer will set the technical direction for the intelligence layer that powers ZoomInfo AI agents.
- This senior individual contributor role involves owning strategy across the data graph, entity resolution, and buying intent while remaining hands-on with complex technical problems.
- The role requires defining evaluation standards and technical defaults that are adopted across multiple engineering teams.
Responsibilities
- Set technical strategy for the data graph, entity resolution, buying intent, and agent context.
- Frame and ship solutions for complex problems like web-scale semantic intent and extraction for companies with no public footprint.
- Define evaluation standards including sampling methodology, human labels, validated LLM judges, and release gates.
- Define data contracts between the data graph, intent signals, and consuming agents.
- Establish baseline performance metrics and uncertainty reporting standards across the group.
- Lead design reviews and mentor senior engineers.
- Shape hiring practices and represent technical judgment to product and leadership teams.
- Make cost and capacity decisions for model training and serving.
Requirements
- Proven experience setting technical direction as an individual contributor for problem areas spanning multiple teams.
- Experience delivering machine learning systems into production and maintaining ownership post-launch.
- Breadth across classical machine learning on large tabular data, applied statistics, language processing at scale, and LLM agents.
- Demonstrated ability to define and drive adoption of evaluation standards for systems without a single right answer.
- Track record of influencing group-wide engineering practices, such as introducing new baselines or review processes.
- Experience making cost and capacity decisions for model training and serving, including cost tracking per unit of work.
- Hands-on proficiency in production Python and SQL.
- Experience with distributed data processing.
- Daily use of AI coding tools with rigorous output review.
Preferred qualifications
- Experience with ranking and retrieval, including embeddings, learned re-ranking, and metrics like recall@k, MRR, and nDCG.
- Experience with entity resolution, knowledge graph, or web-scale information extraction on messy data.
- Experience training and serving open-weight models in PyTorch or equivalent frameworks.
- Experience with GPU capacity planning.
- Experience building user memory or context systems for agents.
- Experience defending LLM systems against adversarial inputs and prompt injection.
Benefits
- Comprehensive benefits package
- Holistic mind, body, and lifestyle programs
Workplace
- Role is remote-eligible.
Skills
- Python
- SQL
- Machine Learning
- LLM
- PyTorch
- Distributed Data Processing
- Entity Resolution
- Knowledge Graph
- Applied Statistics
