Hi there 👋, my name is

Stephane

& I'm a Machine Learning Engineer

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About Me

Originally from France, I've been working as a machine learning engineer in the U.S. since 2013, but I've always been passionate about mathematics — even before it was cool. Nowadays, I play with math and data for a living as I have built up the following three competencies:

Machine/Deep Learning Modeling

From simple models to much advanced ones that I authored, I have extensive hands-on experience training and using Machine Learning models and LLMs that solve complex business problems.

Data
Engineering

I'm no stranger to building batch and real time pipelines to process massive amounts of data.

MLOps & Infrastructure

I have designed and implemented ML platforms from scratch in Google and AWS to productionize models at scale.

Links

You can see my work on Github and/or follow me on LinkedIn.

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Appearances/Projects

U.S. Patent

I invented an AI-powered recommender system that turns users and products/services into comparable vectors in the same embedding space and then matches them with the best-fit services in near real‑time.
Check out U.S. Patent No.12,026,759

NVIDIA GTC 2021

I had the opportunity to represent my multidispliniary team at the NVIDIA GTC conference. I spoke about how Square introduced personalized lists of products that would be the most useful for its millions of merchants worldwide, using a deep learning-based recommender system.
Check out the video here.

Papers

I authored two papers. The first one was about survival analysis in which I introduced a novel deep learning-based survival analysis model, using PyTorch, designed to compute when events are likely to occur.
Check out the survival analysis model here.

The second one introduced a customer support model, which ranked the most relevant solutions to a user's inquiry by leveraging word embeddings from the submitted email questions.
Check out the customer support model here.

Open Source

I open-sourced a python package to help the machine learning community build survival analysis models seamlessly.
Check out the python package here.

Blog Posts

To represent the data science community at Square, I wrote a few blog posts that covered the work we did.
Check out one of my blog posts here.
Check out another one of my blog posts here.

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Work, Education & Skills

Work

Webflow (Y Combinator S13)

Staff Machine Learning Engineer
September 2022 - Current
  • Developed a deep learning-based risk detection system (e.g., spam, phishing) for the Trust & Safety team, achieving a false positive rate below 0.1%. This multimodal PyTorch architecture integrated three modules through a custom Transformer Encoder layer:

    ⭐️ Computer vision for site screenshot embeddings via fine-tuned from OpenAI CLIP
    ⭐️ NLP for text vectorization via fine-tuned from OpenAI CLIP
    ⭐️ Tabular data from site metadata.
    Created via distributed training and deployed with Airflow, the system automatically removed over 280,000 fraudulent sites, saving $150,000+ annually by eliminating the need for third-party services and human intervention.
  • Built a production-grade customer support system that reduced average ticket resolution time by 20% while scaling to over 10,000 tickets/month. It combined:

    ⭐️ A multi-task PyTorch classifier (cross-entropy + supervised contrastive learning), where tickets were vectorized using fine-tuned GTE text embeddings for accurate routing
    ⭐️ A summarization module powered by open-source LLMs (Phi-3, later Qwen2-7B-Instruct), using vLLM providing an OpenAI-compatible API.

    Both models were deployed via SkyPilot on an L4 multi-GPU cluster, with a FastAPI app handling async requests to both components, delivering scalable, low-latency inference while ensuring full data privacy on a self-hosted LLM stack.

PointCard (Y Combinator W19)

Staff Machine Learning Engineer
February 2022 - Current
  • Designed and built the company’s first MLOps platform in AWS, enabling scalable, end-to-end workflows across both staging and production environments.

    ⭐️ Created a real-time inference engine using FastAPI, Docker, and Kubernetes, alongside batch pipelines
    orchestrated with Apache Airflow and custom operators
    ⭐️ Used SageMaker for model development, with MLflow for versioning and registry management
    ⭐️ Deployed containerized apps via ECS and ECR, and implemented CI/CD pipelines with GitHub Actions
    ⭐️ Built a private Python package repository with CodeArtifact, and provisioned cloud infrastructure using Pulumi (IaC)
  • Configured a Databricks Spark cluster for large-scale ETL pipelines processing terabytes of data from Redshift and S3 (Avro, Parquet, JSON), reducing manual overhead by 11%.
  • Integrated Kafka consumers and Spark Streaming to support real-time data ingestion and processing.

Block, inc. (fka Square, inc.)

Staff Machine Learning Engineer
February 2021 - February 2022
  • Designed and built a deep learning-based recommendation system in PyTorch to serve millions of sellers with personalized product suggestions. The two-tower model architecture (user + product) featured:

     ⭐️ A user tower that processed engineered features and sequences of past actions fed to an RNN.
     ⭐️ A product tower that used a fine-tuned BERT encoder on textual descriptions.

    The model was trained on NVIDIA A100 GPUs using a custom information retrieval loss function implemented from scratch based on academic research. It achieved a 15% lift in A/B testing over existing ranking methods, contributing to $5M+ in additional annual revenue.
    The system became the basis of a patent and was presented at NVIDIA GTC 2021.
  • Created a Python package designed to vectorize any text or images, using Transformer-based models for NLP and Computer Vision for Tensorflow/Keras and PyTorch. It was containerized, deployed as a microservice and made available via a REST API.
Senior Machine Learning Engineer
April 2017 - February 2021
  • Led the development of an internal deployment platform that streamlined ML serving by automatically converting trained models into FastAPI-based servers, containerizing them with Docker, and deploying them to Kubernetes clusters on GCP, significantly reducing engineering overhead and time-to-production.
  • Developed a LightGBM-based cross-sell model that prioritized high-propensity users, driving an 18% increase in sales conversion rates. The model surfaced daily ranked opportunities to account managers via Airflow, enabling more targeted and effective outreach based on predicted conversion likelihood.
  • Authored a novel deep learning-based survival analysis model, using PyTorch, designed to compute when users would repay their Square Capital loans in full.
  • Prototyped a novel deep learning-based model for customer support that ranked the most relevant solutions to a user's inquiry by leveraging word embeddings from the submitted email questions.

Education

  • MA, Mathematics, 2013 | Columbia University, New York, NY
  • MS, Applied Mathematics, 2012 | Ecole des Mines, Nancy, France
  • BS, Engineering, 2011 | Ecole des Mines, Nancy, France

Skills

  • Cloud & Infrastructure:
    AWS (EC2, EKS, S3, SageMaker, Redshift), Google Cloud Platform (GCP), Databricks, Data
    Warehouse (Snowflake), BigQuery, RDS, PostgreSQL, Apache Spark, Kafka, Pulumi, Kubernetes, Docker
  • Machine Learning Frameworks & Libraries:
    PyTorch, JAX, TensorFlow, Huggingface Transformers,
    Scikit-learn, CatBoost, XGBoost, LightGBM
  • ETL/ELT (Airflow, dbt)
  • Agentic & LLM Tools: Agno, Langchain, vLLM, SkyPilot, FAISS
  • Model Deployment & Serving (MLOps): FastAPI, Flask, Ray Serve, MLflow
  • Computer Science, Software Engineering & Tooling: Python, SQL, Bash, Linux, Git (GitHub, GitLab), Pandas, Polars,
    NumPy
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