Joel Feinstein
Software Engineer at Citadel
New York, New York, United States
Summary
👤
Senior🎓
Top SchoolJoel Feinstein is a full-stack software engineer with 12 years of experience building reliable, data-driven systems across startups and major tech firms, currently engineering at Citadel in New York. He has shaped technical direction as a principal engineer at LoanStreet and productized large-scale ML and data platforms at Amazon, demonstrating deep familiarity with cloud services and production deployment. Joel’s contributions to notable open-source projects—like GORM for Go, JetBrains’ Exposed for Kotlin, and the mongoid-history auditing library—highlight his backend and database expertise, particularly in query building, associations, caching, and auditability. His background spans firmware and low-level system work at Qualcomm to UI and real-time analytics at Nyansa, showing a rare full-stack fluency from C++/kernel-level code to frontend frameworks and GraphQL. He combines academic rigor from Carnegie Mellon with hands-on leadership, often driving performance and maintainability improvements that go beyond feature work.
12 years of coding experience
10 years of employment as a software developer
Bachelor of Science (B.S.), Double Major - Computer Engineering, Engineering & Public Policy, Bachelor of Science (B.S.), Double Major - Computer Engineering, Engineering & Public Policy at Carnegie Mellon University
English, Hebrew
Stackoverflow
3reputation
0reached
0answers
0questions
Github Skills (21)
kotlin10
rspec10
dao10
object-oriented-programming10
mongodb-database10
ruby10
go10
orm10
sql10
database-design10
mongodb10
testing9
schema-design9
db-schema9
database-schema9
Programming languages (11)
Github contributions (5)
mongoid/mongoid-history
Sep 2016 - Aug 2018
Multi-user non-linear history tracking, auditing, undo, redo for mongoid.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:6 commits, 4 PRs, 27 comments in 1 year 11 months
Contributions summary:Joel made significant contributions to the `mongoid-history` repository, focusing on the implementation of features related to tracking and formatting data changes. Their work included adding helpers for tracking embedded relations and implementing obfuscation features with corresponding tests and documentation updates. Furthermore, the user addressed issue #226 and #225 by storing options in inheritable class attributes, enhancing the overall maintainability and stability of the history tracking functionality.
mongoidnon-linearlineartrackingredo
JetBrains/Exposed
Jan 2021 - Aug 2021
Kotlin SQL Framework
Role in this project:Back-end Developer / Database Engineer
Back-end Developer / Database EngineerContributions:15 reviews, 15 commits, 13 PRs in 7 months
Contributions summary:Joel primarily focused on improving the Kotlin SQL Framework. Their contributions include refactoring typing in the transaction execution, optimizing entity cache behavior, and allowing for eager loading of any iterable. Furthermore, they enhanced the framework by explicitly supporting the setting of a default database and adding a linting configuration. They also addressed several issues with cache flushing and bulk operations within the entity cache to optimize performance.
mysqlsqlkotlinsqliteorm
Find and Hire Top DevelopersWe’ve analyzed the programming source code of over 60 million software developers on GitHub and scored them by 50,000 skills. Sign-up on Prog,AI to search for software developers.