Open to opportunities

William Massey

@williammassey

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Senior data engineer with expertise in building scalable data solutions.

United States

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What I'm looking for

I am looking for a role that fosters innovation and collaboration, where I can leverage my data engineering skills to drive impactful projects and contribute to a forward-thinking team.

As a Senior Data Engineer with a decade of experience, I specialize in building ingestion pipelines and modeling analytics layers that drive AI insights for real-world applications. My expertise lies in designing end-to-end data platforms on AWS and Azure, ensuring reliability and clarity while delivering significant business impact.

Throughout my career, I have developed innovative LLM-powered tools that support internal teams, scaled event-based systems for healthcare and financial data, and led core BI initiatives that have shaped executive decisions. My work has consistently focused on reducing engineering overhead and establishing a solid foundation for scalable analytics using technologies such as Snowflake, Redshift, and Spark.

Experience

Work history, roles, and key accomplishments

Current

Senior Data Engineer

Current

UnitedHealth Group

Jun 2021 - Present (3 years 11 months)

Led the development of an internal LLM-powered assistant for clinical and claims teams, integrating with Optum’s knowledge base. Designed a scalable metrics layer for 70+ dashboards, migrated legacy SQL scripts to dbt models, and built ingestion pipelines processing over 150M records monthly. Improved performance and reduced costs significantly.

AWS DBT Power BI Snowflake Spark Airflow Kafka SQL LLM

Data Engineer

Flatiron Health

Jan 2018 - Apr 2021 (3 years 3 months)

Engineered robust data pipelines for EHR and clinical trial data, modeling patient cohorts in Snowflake. Built a centralized metrics layer in Azure Synapse, significantly reducing manual work and improving onboarding for analysts.

Spark Airflow Snowflake Azure Synapse SQL EHR Data Modeling Metrics

Data Engineer

Etsy

Jan 2016 - Dec 2017 (1 year 11 months)

Developed ETL pipelines to ingest large volumes of clickstream and transaction data into Snowflake. Designed star-schema data marts and real-time monitoring dashboards, enhancing productivity and data governance.

Spark Python Snowflake Kafka Power BI ETL Data Marts Terraform

Data Engineering Intern

Chewy

Jul 2015 - Jan 2016 (6 months)

Created SQL dashboards for analyzing cancellations and support tickets, normalized vendor data for integration into Power BI, and optimized Redshift queries for operational teams.

SQL Power BI Redshift Dashboarding