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Senior Data Scientist

Zefr, Inc.

Job Overview

Location

Marina del Rey, CA

Job Type

Full-time

Full Job Description

📋 Description

• As a Senior Data Scientist at Zefr, you will drive innovation in brand safety and suitability by advancing the research and production deployment of Large Language Models (LLMs) for multimodal social media content understanding, directly enabling advertisers to control content adjacencies in alignment with GARM standards across YouTube, Meta, TikTok, and other major platforms.
• You will own the end-to-end lifecycle of LLM-powered systems—from prototyping and fine-tuning open-source and closed-source models to optimizing inference for latency, cost, and quality, and deploying scalable, production-grade pipelines using cutting-edge MLOps and GPU-accelerated technologies.
• You will collaborate with a global team of engineers and researchers to build compound AI systems that integrate multiple modalities (video, image, text) into reliable, high-throughput solutions that process multi-terabytes of social media data daily.
• You will contribute to Zefr’s mission of powering responsible marketing by leveraging patented Cognition AI technology, working within an official YouTube Measurement Program Partner, Meta for Business Partner, and TikTok for Business Partner environment that prioritizes transparency, precision, and scalability in brand suitability measurement.
• You will deepen your expertise in state-of-the-art LLM optimization techniques—including KV cache management, quantization, multi-node GPU serving, and frameworks like vLLM and TensorRT LLM—while gaining hands-on experience with distributed systems, cloud infrastructure (AWS/GCP), and tools like HuggingFace, Weights & Biases, and NVIDIA Triton.
• You will grow as a technical leader by mentoring peers, advocating for rigorous testing and code review practices, and influencing architectural decisions that balance innovation with production readiness in a fast-evolving AI landscape.

🎯 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

🏖️ 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

Skills & Technologies

Python

Node.js

FastAPI

AWS

GCP

Data Science

Senior

Remote

Degree Required

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Zefr, Inc.

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About Zefr, Inc.

Zefr provides brand suitability and contextual targeting technology for advertisers on YouTube, TikTok, Facebook and other social video platforms. Its machine-learning systems scan and classify millions of videos daily, mapping content against GARM and brand-specific safety standards to ensure ads appear only alongside appropriate material. The company delivers dashboards, verification reporting and programmatic integrations that help marketers maximize reach while minimizing reputational risk. Founded in 2009 and headquartered in Los Angeles, Zefr works with global agencies and Fortune 500 brands to align campaigns with brand values and regulatory requirements.

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