Jeff Kantarek
Senior Software Engineer at Shopify
Chicago, Illinois, United States
Summary
👤
Senior🎓
Top SchoolJeff Kantarek is a seasoned software engineer and engineering leader with 10+ years building and scaling backend systems for startups and large organizations, currently at Shopify after leading engineering at Medallion. A Ruby-first developer who pairs deep Postgres/SQL fluency with practical experience in Python, Elixir, and JavaScript, he has a knack for turning data into product decisions and shipping reliable infrastructure (from Kafka pipelines to GraphQL and Datadog E2E suites). Jeff has repeatedly stabilized underperforming teams, mentored engineers into senior roles, and built engineering standards used across organizations—work that helped drive a $450M Series C healthcare SaaS scale-up. He holds an MS in Energy Engineering, a patent-driven history of productization, and real-world embedded-to-cloud experience from founding startups to integrating Trunk Club into Nordstrom’s fulfillment stack. Known for pragmatic, data-informed leadership, he also experiments with LLMs and prompt engineering to push product capabilities beyond conventional engineering patterns.
10 years of coding experience
17 years of employment as a software developer
Marian Catholic High SchoolMS Energy Engineering, MS Energy Engineering at University of Illinois Chicago
Github Skills (26)
gitbook9
fulfillment8
displays7
jekyll7
jekyll-theme7
html6
type-validation6
sinatra6
type-coercion5
ruby5
yard5
validation5
coercion5
vscode4
rails4
Programming languages (4)
Github contributions (5)
chiengineer/json_svc_ex
Oct 2016 - May 2017
Contributions:58 commits, 27 PRs, 62 pushes in 7 months
apielixirbase-projectjson-apijson
jkantarek/advent_of_code
Dec 2021 - Dec 2023
Contributions:36 PRs, 33 pushes, 42 branches in 2 years
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