Hybrid Senior Data Scientist

at Zefr

• Job title: Senior Data Scientist
• Job type: Full Time
• Experience level: Senior
• Salary: $200,000 - $225,000 per year
• Degree requirement: Bachelor's Degree
• Tech skills: Distributed Systems, Node.js, Python, SQL
• Location requirements: Hybrid, Marina del Rey, United States

About the role

• Senior Data Scientist at Zefr focusing on Large Language Models for multimodal social media. Collaborate on fine-tuning and deploying AI systems to understand social media content.

Responsibilities

• We are hiring a Senior Data Scientist focused on the research and productionalization of Large Language Models for multimodal social media content understanding.
• Work with multi-terabytes of social media platform data from TikTok, YouTube, Facebook, Instagram, and Snap.
• Fine-tune, optimize, and deploy LLMs that understand what hundreds of millions of videos, images, and text posts are about.
• Span the full lifecycle — from research and prototyping to production-grade serving at scale.
• Build sophisticated compound AI systems that combine multiple models and modalities into reliable, scalable pipelines.

Requirements

• Bachelor's or Master's degree in Computer Science or related field with 4+ years of professional experience in machine learning or data science
• Hands-on experience fine-tuning large language models (open-source and/or closed-source)
• Experience with LLM inference optimization — KV cache management, quantization, multi-node GPU serving, batching strategies, and serving frameworks (vLLM, TensorRT LLM, SGLang)
• Track record of taking ML models from research to production at scale
• Fluency with Python and SQL (specifically Snowflake)
• Experience working with multimodal models and features
• Familiarity with cost/quality tradeoff analysis across LLM providers and self-hosted models
• Experience with distributed systems and GPU-accelerated workloads
• Strong foundation in data structures, algorithms, and software design
• Thorough testing and code review standards/practices
• Strong verbal and written communication skills
• Experience working with Autonomous Coding Agents
• Openness to new technologies and creative solutions

Benefits

• Flexible PTO
• Medical, dental, and vision insurance with FSA options
• Company-paid life insurance
• Paid parental leave
• 401(k) with company match
• Professional development opportunities
• 13 paid holidays off
• In-office, hybrid, and fully-remote work options available
• “Summer Fridays” (shorter work days on select Fridays during the summertime)
• In-office lunches and lots of free food
• Optional in-person and virtual events (we like to celebrate!)