Joe Leo
CEO at Def Method
New York, New York, United States
Summary
👤
Senior🎓
Top SchoolJoe Leo is a founder and CEO who specializes in modernizing high-risk, revenue- and compliance-sensitive Rails systems with 11+ years of hands-on engineering and leadership. He leads Def Method and pioneered assessment-first engagements that make technical and operational risk explicit before any modernization work, reducing outages and costly surprises. His work spans regulated fintech, healthcare, and enterprise SaaS, including projects that cut settlement times from seven days to one, globalized pricing across six countries, and migrations of 200,000 users with zero outage. Joe is co-author of The Well-Grounded Rubyist (3rd ed.), hosts The Ruby AI Podcast, and has guided modernization for organizations like Citi, Paxos, Walmart, MoMA, and the NYC Campaign Finance Board. He brings a pragmatic blend of architecture, test confidence auditing, and evidence-based modernization sequencing—helping teams move safely rather than just faster. Based in New York, he’s as comfortable advising C-suite priorities as he is untangling fragile test suites and operational dependencies.
11 years of coding experience
7 years of employment as a software developer
MA Arts, MA Arts at New York UniversityBS Economics, BS Economics at Penn State UniversityHoly Trinity High School
Github Skills (17)
gemfile9
constraint8
operator5
sketchup5
installer5
ruby5
mruby4
shell3
jruby3
nvm2
rubinius1
rails1
youtube1
ruby-install1
ruby-on-rails1
Programming languages (3)
Github contributions (5)
defmethodinc/jasmine-fixture-builder
May 2015 - Jan 2017
Contributions:9 commits, 13 PRs, 26 pushes in 1 year 8 months
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