Currently at Shopify

Zhenqing (ZQ) Li

Senior Applied Machine Learning Engineer

ML engineer and data scientist building LLM-powered search at Shopify. Background spanning a decade in fintech and materials science research.

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About

I'm currently a Senior Applied Machine Learning Engineer at Shopify, where I build next-generation search models for Shopify storefronts and the Shop app using fine-tuned LLMs. I also developed an LLM-as-a-judge evaluation system to automate search quality assessment and reduce manual labeling overhead.

Before Shopify, I spent eight years at Capital One, growing from Principal Data Scientist to Senior Manager. I led teams across pricing strategy, causal inference, and risk modeling — work that guided a $1.5B credit portfolio, contributed $70M in incremental revenue, and helped prevent over $100M in potential quarterly losses.

My roots are in materials science — I hold a PhD from The Ohio State University and spent four years at Lubrizol as a research chemist, where I built statistical models to predict chemical toxicity and developed image processing tools — early applied ML work before I had a name for it. That scientific foundation shapes how I approach ML: methodical, experiment-driven, and skeptical of results that seem too good.

I like to call myself a hybrid engi-scientist — equally at home reasoning about causal identification, tuning an LLM eval pipeline, and explaining results to a business stakeholder.

Experience

Senior Applied Machine Learning Engineer

Shopify — Remote

Sep 2024 – Present
  • Built LLM-as-a-judge evaluation system to automate search quality assessment, improving relevance and reducing manual labeling costs
  • Building next-generation Shopify storefront and Shop search models using fine-tuned LLMs; leading experimentation, evaluation, and rollout

Senior Manager, Data Science

Capital One — McLean, VA

Jan 2022 – Jun 2024
  • Led team designing causal models for customer management and pricing, guiding a $1.5B credit portfolio
  • Delivered LSTM-based risk model enabling interventions that reduced potential quarterly loss by $100M
  • Built causal model for credit utilization prediction, expanding program reach by 20%

Manager, Data Science

Capital One — McLean, VA

Aug 2018 – Jan 2022
  • Developed pricing model contributing $70M in incremental revenue from credit line increases
  • Rebuilt transaction fraud model preventing $4M in additional fraud
  • Led challenger model development for Capital One's Main Street risk model

Principal Data Scientist

Capital One — McLean, VA

Sep 2016 – Aug 2018
  • Validated behavior, fraud, and recommendation models within the Model Risk Office
  • Built AWS-based data engineering pipelines for model validation workflows

Research Chemist

Lubrizol — Wickliffe, OH

Jun 2012 – Sep 2016
  • Built statistical model to predict chemical toxicity, avoiding $1M in regulatory registration costs
  • Applied Design of Experiments to accelerate new product development and developed rheology modifiers

Skills

Languages & Libraries

Python PyTorch NumPy / SciPy Pandas / Polars Spark SQL

Infrastructure

AWS (EMR · S3 · SageMaker) Terraform Kubernetes Docker

ML & Statistics

LLMs & Fine-tuning Machine Learning Causal Inference Experimental Design Statistical Modeling

Open Source Projects

Education

2008 – 2012

PhD, Materials Science & Engineering

The Ohio State University, Columbus, OH

2006 – 2008

MS, Materials Science & Engineering

Clemson University, Clemson, SC

2002 – 2006

BS, Macromolecular Science & Engineering

Fudan University, Shanghai, China

Full publication list on Google Scholar.