Staff Machine Learning Engineer

Primer exists to make the world a safer place. We build trusted, decision-ready AI for the organizations that can least afford to be wrong: the leaders, operators, and analysts making high-stakes calls about a world that changes faster than anyone can read it. We have offices in San Francisco, Pasadena, CA, and Arlington, VA. Learn more at primer.ai.  The world produces more information every day than any team can read. We build the AI that turns it into a decision you can trust: fast and grounded enough to stake real consequences on.

As a Staff Machine Learning Engineer, you’ll own AI-driven products end to end, from the prototype that proves an idea works to the production system the mission depends on. You work fluently across the modern stack: large language models, agentic systems, retrieval, embeddings, fine-tuned models, and the evaluation harnesses that catch them when they drift. You can move fast on an open-ended problem and then harden the result into something reliable at scale, drawing on real distributed-systems experience. You’re energized by what frontier models and agents make newly possible. You reach for them reflexively, including to multiply your own output, and you raise the level of everyone around you as you go.

Your technical range matters as much as your judgment about how the pieces fit together. The best work here is designed as part of the whole system, not bolted on beside it, and the engineers with the most impact bring product managers and teammates along with them rather than around them. You’ll partner with product, engineering, and other technical leaders on the hardest version of the problem: putting real AI in the hands of people the moment a decision can’t wait.

Job responsibilities - How You Will Make an Impact• Set both technical and product direction, making the strategic bets across our LLM, agentic, and NLP systems while shaping how we design AI-driven experiences and set expectations with users.

• Design and build the distributed, agentic systems behind our products at company-wide scale: tool-using conversational agents, multi-turn context, retrieval-grounded reasoning, and the orchestration that ties them together.
• Turn massive, messy, real-world data into the trustworthy signal agents' reason over: entity recognition and linking, relation extraction, summarization, semantic search, and knowledge-graph generation.
• Take models from checkpoint to production: package, deploy, and operate low-latency, high-concurrency inference (Triton, vLLM, GPU-backed serving) that stays fast and reliable under real load.
• Build the evals and labeled-data flywheels that steer the work rather than gate it, turning “it feels better” into proof you can act on.
• Partner with and influence cross-functional teams to shape the technical roadmap, and drive issues to root cause when quality or operations are on the line.
• Raise the engineering bar with better patterns, better practices, and a standard other engineers want to match.

Relevant Skills and Experience• BS, MS, or PhD in computer science, a related field, or equivalent practical experience.

• 6+ years building production backend software, with a track record of shipping and operating ML-driven functionality.
• Mastery of data structures and algorithms, and the judgment to translate user needs into practical solutions.
• Hands-on depth with LLMs and agentic systems (prompt and context engineering, tool use, retrieval and RAG) and the broader ML toolkit such as PyTorch, plus experience defining evals to measure and improve quality.
• Fluency authoring production APIs in Python (Rust a plus).
• High agency and a bias to action in ambiguous, fast-moving problems, plus the curiosity, generosity, and love of teaching that lifts a whole team.

Bonus Points• Experience with knowledge graphs, information retrieval at scale, or LLM fine-tuning and post-training.

• A pull toward high-stakes, real-world problems where the work actually ships and someone depends on the answer.

Primer works closely with the U.S. defense and intelligence establishment. Any offer of employment is conditioned on an applicant or employee being able to meet any applicable government contract requirements. The company may rescind any offer of employment to an applicant or terminate an employee if the applicant or employee is unable to perform the functions of the position in compliance with applicable government contracts or if an applicant or employee makes a false attestation of compliance. What We Offer At Primer, we are building innovative technology with a team of talented, passionate individuals who are driven to make an impact. As a Series D-funded company backed by leading investors, including Addition, USIT, Lux Capital, Amplify Partners, and Bloomberg Beta, we are committed to fostering a diverse, inclusive, and collaborative workplace where different perspectives and expertise drive innovation.

We believe great work starts with taking care of our people. We prioritize employee well-being, work-life balance, and a culture that encourages flexibility, professional growth, and sustainable performance. Our goal is to create an environment where every team member feels supported, valued, and empowered to do their best work. We offer competitive compensation and a comprehensive benefits package designed to support our employees and their families, including:

• Health & Wellness: Comprehensive medical, dental, and vision coverage, along with One Medical membership.
• Mental Health Support: On-demand mental health and well-being resources through Headspace Care+.
• Family & Fertility Benefits: Fertility and family-building support through Carrot, along with 100% paid parental leave.
• Fitness & Well-Being: Access to fitness and wellness programs through Wellhub (formerly Gympass).
• Work-Life Balance: Flexible vacation policy, dedicated Wellness Days, and a culture that encourages employees to recharge.
• Financial Wellness: Competitive compensation and a 401(k)-retirement savings plan.
• Remote Work Support: Remote work stipends and a monthly internet allowance to help employees stay connected and productive.

At Primer, we're committed to creating a workplace where our people can grow, thrive, and make a meaningful impact while maintaining a healthy balance between work and life.