Principal Applied AI / ML Engineer

About this role:

We are seeking a Principal AI / ML Engineer to be a company-level technical thought leader and practitioner to help shape the future of Data and AI at Faire. This is a rare opportunity to drive broad technical strategy across data, engineering, and product while remaining deeply hands-on with cutting-edge AI research and applications. This role reports directly to the CTO of Faire.

You will:

1. Shape the AI vision – Partner with product, design, strategy & analytics, machine learning, and the broader engineering leadership to define how AI can deliver transformational value to Faire’s retailers and brands. Offer thought leadership to shape company-wide priorities, with particular focus on product strategy and key investment directions.
2. Prototype and unblock – Build and lead deployment of AI systems (LLM fine-tuning, RLHF, agent frameworks, etc.) that demonstrate what’s possible and accelerate adoption across teams. Act as a “super IC” who can dive deep to remove technical barriers, enabling the engineering organization to move quickly with AI and accelerate both development and impact.
3. Architect the AI-ready stack – Shape the design of Faire’s technical ecosystem — spanning event logging, data warehouses, feature stores, and model serving — to ensure our infrastructure is AI-ready, scalable, and optimized for rapid experimentation and the safe & reliable deployment of innovative AI-enabled features.

What you’ll do:

• Serve as a trusted partner to executives and senior leaders, informing long-term strategy and product direction for AI-enabled experiences.
• Prototype and deploy cutting-edge AI systems using LLMs, generative AI, and agentic frameworks — taking concepts from zero-to-one and helping teams productionize them.
• Define technical standards and evaluation frameworks for safety, reliability, and business impact of AI features.
• Partner with infrastructure and platform teams to evolve Faire’s data pipelines, ML serving stack, and developer tools for AI-driven velocity.
• Mentor engineers and scientists across the org, raising the technical bar through coaching, tooling, knowledge sharing, and design reviews.
• Evangelize AI best practices and foster a culture of innovation that balances bold experimentation with pragmatic delivery.

Who you are:

• 10+ years of experience training and deploying machine learning models at scale, conducting applied AI research, and productizing advanced AI/ML technologies for impact.
• Proven track record of delivering production-grade AI systems at scale and influencing product strategy. Great at operating at the intersection of tech and product.
• Deep expertise in LLMs and modern AI techniques: fine-tuning, RLHF, RAG, embeddings, and agent frameworks.
• Strong systems background: experience with large-scale data pipelines, ML feature stores, distributed training, and model serving infrastructure.
• Proficiency with PyTorch, TensorFlow, JAX, Triton, or other relevant AI development and production frameworks.
• Exceptional communication and influence skills — able to collaborate with executives and inspire technical and non-technical audiences alike.
• MS or PhD in Computer Science, Machine Learning, Statistics, Operations Research or related field (or equivalent experience).
• Bonus: Open-source contributions, peer-reviewed publications, or experience in two-sided marketplace ecosystems.

Salary range:

San Francisco: the pay range for this role is $339,000 to $466,000 per year. 

This role will also be eligible for equity and benefits. Actual base pay will be determined based on permissible factors such as transferable skills, work experience, market demands, and primary work location. The base pay range provided is subject to change and may be modified in the future.