Yoshifumi Kawai
CEO, CTO at Cysharp, Inc.
Chiyoda, Japan
Summary
🤩
Rockstar🎓
Top School
Top expert inUnity and Unreal Engine Game Development
Yoshifumi Kawai is a seasoned C# engineer and technology founder with 13 years of professional experience and a decade focused on advanced C# and meta-programming techniques, now serving as CEO/CTO of Cysharp. He led the creation and popularization of UniRx for Unity and maintains a prolific open-source footprint—56 GitHub repositories and 75 NuGet packages—ranking in the global top 25 C# contributors and earning Microsoft MVP recognition for six years. His work spans high-performance systems (MemoryPack, ZString, MessagePipe), zero-allocation tooling (ZLogger, UniTask), and source-generator-driven libraries for .NET and Unity, reflecting a deep emphasis on runtime efficiency and AOT safety. As an operator he scaled engineering from 10 to 100 people, ran company strategy and developer evangelism, and served as CTO on high-traffic game backends using gRPC and distributed architectures. An uncommon strength is combining low-level optimization (IL/meta-programming) with product-scale architecture and developer experience, making him equally comfortable shipping benchmarks as leading technical teams.
13 years of coding experience
10 years of employment as a software developer
Bachelor’s Degree, Mathematical Sciences, Bachelor’s Degree, Mathematical Sciences at 東海大学
Stackoverflow
48reputation
2kreached
2answers
1question
Github Skills (63)
asynchronous10
concurrent-programming10
strings10
lib10
console10
async10
binary-search10
linq10
testing10
text-manipulation10
net10
binary-format10
dotnet10
formatter10
user-interface10
Programming languages (6)
Github contributions (5)
Cysharp/MemoryPack
Sep 2022 - Jan 2023
Zero encoding extreme performance binary serializer for C# and Unity.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1 review, 345 commits, 78 PRs in 4 months
Contributions summary:Yoshifumi appears to be primarily focused on implementing core serialization and deserialization logic within the `cysharp/memorypack` repository. Their contributions involve creating and modifying code related to serialization contexts, formatters, and the core serialization process. The user demonstrates skills in C# language and related libraries.
extremezeroserializationencodingperformance
Cysharp/MessagePipe
Apr 2021 - Oct 2022
High performance in-memory/distributed messaging pipeline for .NET and Unity.
Role in this project:Back-end Developer
Back-end DeveloperContributions:203 commits, 43 PRs, 101 pushes in 1 year 6 months
Contributions summary:Yoshifumi's commits primarily involve the development of core components for a messaging pipeline within the .NET and Unity environments. They focused on implementing the structure for a keyed messaging system and integrating different implementations of these brokers such as a concurrent dictionary and immutable array based implementations. The commits show changes to the core messaging handling classes, indicating a significant role in developing and refining the library's core functionality. The user's work involved setting up the infrastructure for publish and subscribe functionality.
distributed-memorydotnetmemorydistributed-messagingpipeline
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