James Onnen
Senior Software Engineer at Studio Koi Koi
Bellevue, Washington, United States
Summary
🤩
Rockstar🎓
Top SchoolJames Onnen is a Senior Software Engineer with 14 years of experience building full-stack systems, developer tools, and game platforms across Microsoft and Roblox. He designs and ships production features—from Git integration and Visual Studio performance improvements to conversational AI-driven material generation and trust-and-safety systems at Roblox—while mentoring teams and improving developer workflows. An entrepreneur and maker, he founded Studio Koi Koi and has run a successful indie Roblox game business that generated significant plays, merchandise, and community recognition. A prolific open-source contributor, James has improved core Roblox tooling such as Rojo and NevermoreEngine, solving cross-platform path issues and refactoring engine internals for modern APIs. Based in Bellevue, WA, he combines product-minded engineering with a hands-on creators’ perspective that spans C++, C#, Lua, TypeScript, and embedded C.
14 years of coding experience
5 years of employment as a software developer
Bacheler of Computer Engineering, Computer Engineering, Senior, Bacheler of Computer Engineering, Computer Engineering, Senior at University of Nebraska, LincolnShawnee Mission South High School
English
Github Skills (24)
lua10
framework-design10
optmization10
performance-optimization10
optimisation10
rust10
game-development10
optimization10
file-manipulation9
architecture9
filesystem9
windows9
fileio9
architectures9
physics8
Programming languages (14)
Github contributions (5)
Quenty/NevermoreEngine
Aug 2014 - Jan 2023
ModuleScript loader with reusable and easy unified server-client modules for faster game development on Roblox
Role in this project:
Full-stack Developer
Full-stack DeveloperContributions:2 releases, 83 reviews, 3061 commits in 8 years 6 months
Contributions summary:James primarily contributed to the development of the Nevermore Engine, a ModuleScript loader for Roblox game development. Their work included implementing and refactoring shared and client-side modules, such as the assembly, physics, and character handling modules. Additionally, the user made substantial changes to various aspects of the framework, refactoring method names, improving debug drawing, and updating the internal systems to use the latest version of the Roblox APIs.
luarobloxclient-serverfastergame-development
rojo-rbx/rojo
Dec 2017 - Aug 2022
Rojo enables Roblox developers to use professional-grade software engineering tools
Role in this project:Backend Developer
Backend DeveloperContributions:2 reviews, 6 commits, 2 PRs in 4 years 8 months
Contributions summary:James primarily focused on improving the performance and stability of the Rojo project. Their contributions included fixing high CPU usage issues, optimizing the codebase with `::park()` calls, and removing unnecessary imports. Furthermore, the user added support for long file paths on Windows and implemented optional path support, improving Rojo's functionality and resolving potential compatibility issues.
luarobloxprofessionalsyncroblox-studio
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