Speakers

Keynote Speakers

• 
  Satoshi Tagomori

  @tagomoris

  A Ruby committer, OSS developer, and a PdM at SAKURA internet.

• 
  Charles Nutter

  @headius

  Charles Oliver Nutter has been a JRuby developer for 20 years, now self-funding its development through his startup Headius Enterprises. Charles wants to see Ruby succeed everywhere that other languages succeed, and believes JRuby is the best way to deploy Ruby for mobile devices, desktops, and enterprises.

• 
  Yukihiro "Matz" Matsumoto

  @yukihiro_matz

  The Creator of Ruby

Speakers

• 
  Aaron Patterson

  @tenderlove

  Aaron is on the Ruby core team, the Rails core team, and the team that takes care of his cat, Gorby puff. Someday he will find the perfect safety gear to wear while extreme programming.

• 
  Albert Pazderin

  Passionately building things with Ruby since 2015

• 
  Alexandre Terrasa

  Alexandre has a PhD in computer science and specializes in typing specifications and implementations. He currently works as a Senior Staff Engineer on the Ruby and Rails Infrastructure team at Shopify. He uses his expertise for the adoption of better Ruby tooling and practices including Sorbet and gradual typing. He previously worked as a core developer on the Nit language for which he implemented parts of the compiler, libraries and tools.

• 
  Andrey Marchenko

  I am a Senior Developer at Datadog working on developer tooling for large-scale Ruby applications. I have spent the last few years building test optimization tools that make CI faster and more reliable for hundreds of real world Ruby applications. I am the author of open source datadog-ci gem that includes the most performant and widely used Test Impact Analysis engine for selective test running.

• 
  Andrey Nᴏᴠɪᴋᴏᴠ

  @Envek

  Backend Engineer at Evil Martians

  Software developer with a passion for building and deploying solid Ruby applications that, you know, actually work in production.

  I love to use and build open source software: have authored multiple Ruby gems, tutorials and examples, a contributor to various libraries and tools, and a speaker and habitue of Ruby conferences.

  I currently live in Osaka, Japan with my family and enjoy driving all over Japan.

• 
  Benoit Daloze

  @eregontp

  Benoit Daloze is the TruffleRuby lead and wrote a PhD thesis about making Ruby parallel and fast. He has contributed to many Ruby implementations, including CRuby, TruffleRuby, JRuby and Rubinius. He is the maintainer of ruby/setup-ruby and ruby/spec.

• 
  Charlie Savage

  Charlie Savage is a software architect and long-time Ruby developer with over 20 years of experience. He is the primary maintainer of the Rice Ruby C++ binding library and ruby-prof profiler and a contributor to CMake and ffi-clang. He is Chief Architect at Privateer, building large-scale geospatial and computer-vision systems, and previously founded Zerista which was built on Ruby on Rails.

• 
  Chris Hasiński

  @khasinski

  A developer with fifteen years of experience, mostly interested in Ruby applications performance and machine learning.

• 
  CRuby Committers

  @rubylangorg
• 
  Daichi Kamiyama

  @_dak2_

  I currently work at Timee Inc. in Japan as a product engineer using Ruby. I'm interested in types, architecture, and parsers.

• 
  Daisuke Aritomo

  @osyoyu

  Programmer interested in improving performance. Author of the Pf2 profiler.

• 
  Daisuke Fujimura

  @fd0

  Maintainer of the Ruby binary package on Cygwin, working on it in his spare time. Interested in software packaging, build systems, and platform engineering.

• 
  Edouard Chin

  Edouard is a Staff Production engineer in the Ruby and Rails infra team at Shopify. He's an avid open-source contributor and is interested in developer tooling and developer productivity.

• 
  hadashiA

  @hadashiA

  I'm a game developer and software engineer with experience in large-scale, performance-critical application development across web and game industries. In recent years, I've been actively developing open-source libraries for C# and Unity.

• 
  Hayao Kimura

  @hachiblog

  Co-Founder of Kyobashi.rb. Organizer of Kaigi on Rails. A Software engineer at freee K.K.

• 
  Hiroshi SHIBATA

  @hsbt

  OSS programmer, Ruby committer, maintainer of many OSS such as ruby, rubygems, bundler, rake, rbenv, ruby-build, psych, and administrator of ruby-lang.org. He maintains the infrastructure that supports the development of the Ruby programming language. He is working in public relations of technology for ANDPAD Inc. and full time OSS developer for the Ruby programming language.

• 
  Hiroya Fujinami

  Ph.D. student at SOKENDAI (NII, National Institute of Informatics). Researcher for information security and formal language. Ruby committer. I am the author of Regexp optimization to prevent ReDoS in Ruby 3.2.0.

• 
  Hitoshi HASUMI

  @hasumikin

  Creator of PicoRuby and PicoRuby.wasm. Committer of mruby and mruby/c.

• 
  Ivo Anjo

  @KnuX

  I love to work on Ruby performance and low-level details and that's how I ended up at Datadog where I'm building the production open-source Ruby profiler inside the datadog gem. This gem extensively uses Ruby C APIs so I get to spend a lot of time staring at them.

  I believe in bringing profiling (and observability in general!) to everyone: these kinds of tools should be easy to use and understandable by all Rubyists, and I'm working hard on delivering this vision ;)

• 
  Jacob

  Jacob joined the Ruby Infrastructure team in late 2024 and works on ZJIT. They have a background in binary analysis and are based in Vermont.

• 
  Jeremy Evans

  @jeremyevans0

  Jeremy Evans is a Ruby committer. He the lead developer of the Sequel database library, the Roda web toolkit, the Rodauth authentication framework, and many other Ruby libraries. He is the author of "Polished Ruby Programming". He is the maintainer of Ruby ports for the OpenBSD operating system. He is a Principal Software Engineer at Ubicloud.

• 
  John Hawthorn

  @jhawthorn

  John is a Ruby Commiter, a Rails Core member, and a Senior Staff Software Engineer at Shopify. He’s based in Victoria, Canada.

• 
  Justin Bowen

  Rubyist and AI Researcher with over a decade of experience focused on high-concurrency systems and GPU accelerated computing in Ruby. Pushing for AI tooling in Ruby to compete with Python. I am the creator of Active Agent, Solid Agent and now ragents, a Ractor-native framework for autonomous AI agents. My work focuses on bridging the gap between Ruby's VM internals and the practical demands of modern AI inference and orchestration, specifically regarding memory locality and parallel execution.

• 
  Katsuhiko Kageyama

  I am an embedded software engineer and engineering manager at aptpod, Inc. Outside of my day job, I have been working on personal mruby-related projects for many years. Recently, my focus has been on PicoRuby, MicroRuby, and their practical applications.

• 
  Kazuaki Tanaka

  Core developer of mruby and mruby/c Associate Professor, Kyushu Institute of Technology Embedded Systems and IoT Researcher In particular, I am actively involved in industrial applications of mruby/c.

• 
  Kazuho Oku

  @kazuho
• 
  Koichi ITO

  @koic

  Koichi Ito is a member of the RuboCop core team, the MCP (Model Context Protocol) steering group, and an open source software maintainer. He is a long-time practitioner of Ruby and Rails application development with eXtreme Programming. He is also an Engineering Manager and Distinguished Engineer at ESM, Inc.

• 
  Koichi Sasada

  Koichi Sasada is a programmer, mainly developing Ruby interpreter (CRuby/MRI). He received Ph.D (Information Science and Technology) from the University of Tokyo, 2007. He is currently developing a Ruby interpreter at STORES, Inc (2023-). He is also a director of Ruby Association.

• 
  Kouji Takao

  A software engineer at NaCl Ltd., developing enterprise systems with Ruby for over 20 years. I also dedicate my weekends to teaching K-12 students. My project, Smalruby, is widely used in junior high schools and featured in textbooks, bridging the gap between visual blocks and Ruby code.

• 
  Luke Gruber

  Luke is a Ruby core committer interested in concurrency and parallelism in Ruby's VM. He has an interest in improving Ractors as well as improving Ruby's VM for non-Ractor workloads. He works at Shopify.

• 
  Maciej Mensfeld

  @maciejmensfeld

  I'm Maciej Mensfeld, a Software Architect with 17+ years of Ruby experience. I'm the creator of the Karafka framework, maintainer of Shoryuken, and a member of the RubyGems security team.

  I've spent over 10 years building message processing systems in Ruby.

  When I'm not building processing frameworks or maintaining OSS, I co-organize the Kraków Ruby Users Group.

• 
  Marco Roth

  Marco is a passionate full-stack developer and a dedicated open-source contributor. As a member of the Hotwire and StimulusReflex contributors teams he has open-sourced, maintained, and contributed to several libraries in the Hotwire/Rails ecosystem.

• 
  Masato Ohba

  @ohbarye

  Rubyist working on a banking system and a card payment system at SmartBank, Inc.

• 
  Masatoshi SEKI

  @m_seki

  Masatoshi Seki is a Ruby committer and the author of several Ruby standard libraries including dRuby, ERB, and Rinda. He’s an expert in object-oriented programming, distributed systems, and eXtreme programming. He has been speaking at RubyKaigi every year since 2006 when the Kaigi first started. He has been a speaker at RubyKaigi every year since its first event in 2006 through 2024. Founder of ninja-testing.com.

• 
  Max Bernstein

  Max learned Ruby back when it was at version 1.9 and he is now in his second era of writing Ruby code. He leads the ZJIT team at Shopify. He loves reading about and writing about compilers. When he is not doing that, he is teaching, baking, cooking, riding his bike, and climbing.

• 
  Misaki Shioi

  @coe401_

  Rails application developer. Rubyist, Ruby committer. Member of Asakusa.rb

• 
  monochrome

  @s_isshiki1969

  A hobbyist, loves Ruby and Rust.

• 
  nagachika

  @nagachika

  CRuby committer. CRuby stable branch maintainer. Sound Programmer wannabe

• 
  Nate Berkopec

  @nateberkopec

  Nate is the owner of Speedshop, a Ruby on Rails performance consultancy, and the author of The Complete Guide to Rails Performance. Nate has taught Ruby and Rails performance skills in workshops all over the world, and is a contributor to several open source projects, such as Ruby on Rails, Puma and Sentry.
 His favorite Japanese musical artists are 山下 達郎, 角松 敏生 and カシオペア.

• 
  ODA Hirohito

  @jimlock

  A programmer, Ruby Hacker wannabe.

• 
  Peter Zhu

  @peterzhu2118

  Peter is a Ruby core committer and Staff Engineer at Figma. He works on improving the performance of Ruby and is currently working on Modular GC and the MMTk integration. He is the co-author of the Variable Width Allocation feature in Ruby, which improves Ruby's performance by optimizing the memory layout. He is also the author of ruby_memcheck, a gem used to find memory leaks in native gems and it has found memory leaks in popular gems such as Nokogiri, protobuf, gRPC, and liquid-c.

• 
  Ryosuke Uchida

  Ryosuke is a software engineer who works as a freelancer. He is personally developing IoT and has great interest in the future brought by IoT. He is also an organizer of Roppongi.rb, a regional .rb for Rubyists.

• 
  Samuel Giddins

  Samuel is a Security Engineer at Persona, working on securing people's identities online. By night, he works to optimize Persona's rails monolith. Samuel has been working on Ruby tooling for the past decade, and has shipped hundreds of bugs across RubyGems & Bundler.

• 
  Samuel Williams

  @ioquatix

  Samuel Williams is the author of Falcon and Async, and a core contributor to Ruby’s concurrency ecosystem. He works on making Ruby fast and scalable in production, and maintains several open-source libraries.

• 
  Sangyong Sim

  @riseshia

  Software engineer at STORES Inc.

• 
  Shigeru Nakajima

  @ledsun

  I am a software engineer at Luxiar Inc. and my hobby is to run Ruby in browser. at Ruby Kaigi 2023, 2024 and 2025, I talked about Ruby in browser using ruby.wasm. Now I am interested in calling Ruby libraries from JavaScript.

• 
  Shintaro Otsuka

  @White_Green2525

  Software Engineer at STORES, Inc. Programming language implementation enthusiast.

• 
  Shunsuke Michii

  @harukasan

  Rubyist and maker who enjoys building electronic projects. Also the CTO of pixiv Inc.

• 
  Soutaro Matsumoto

  @soutaro

  Soutaro is a Ruby core committer who leads the development of RBS and develops Steep – a static type checker built on top of RBS. He works at Shopify as a Senior Engineer on the Ruby DX team.

• 
  Stan Lo

  @_st0012

  Stan is a Ruby committer and maintains Ruby toolings like IRB, Reline, and RDoc. He is a member of Shopify's Ruby Developer Experience Team.

• 
  Sutou Kouhei

  @ktou

  He is a free software programmer and the president of ClearCode Inc. He is also the namer of ClearCode Inc. The origin of the company name is "clear code". We will be programmers that code clear code as our company name suggests. He is interested in how to tell other programmers about how he codes clear code.

• 
  Takashi Kokubun

  @k0kubun

  Takashi Kokubun is a Ruby committer and a member of Shopify's Ruby Infrastructure team. He's currently working on ZJIT, the next generation of YJIT. He has been working on JIT compilers for Ruby since 2017.

• 
  tomoya ishida

  @tompng

  TRICK 2022 Gold Medalist. Ruby committer. Maintaining of IRB, Reline, ReplTypeCompletor, RDoc, BigDecimal. CTO at codeTakt Inc.

• 
  Tsutomu Katsube

  He is a member of the test-unit team and Red Data Tools - Data processing with Ruby!.

• 
  Uchio KONDO

  @udzura

  Rubyist, Rustacean wannabe, and system programming novice, based in Fukuoka, Japan. Product engineer at SmartHR, Inc. Author of "mruby system programming," co-translator of the Japanese edition of "Learning eBPF," organizer of Fukuoka.rb, RubyKaigi speaker since 2016, RubyKaigi local organizer in 2019 at Fukuoka.

• 
  Vladimir Dementyev

  @palkan_tula

  Vladimir is a mathematician who found his happiness in programming Ruby and Erlang, contributing to open source and being an Evil Martian. Author of AnyCable, TestProf and many yet unknown ukulele melodies.

• 
  Yoh Osaki

  @youchan

  Author of Gibier which is presentation tool written by Ruby. Member of Asakusa.rb, Chidoriashi.rb

• 
  Yudai Takada

  @ydah_

  Ruby committer. A committer of Lrama LALR parser generator. Co-Founder of Kyobashi.rb.

• 
  Yuhei Okazaki

  @Y_uuu

  IoT Engineer at Fusic Co., Ltd. , Fjord Boot Camp Mentor, living in Fukuoka, Japan. RubyKaigi 2019 Local Organizer. My hobby is playing with ESP32.

• 
  Yuichiro Kaneko

  @spikeolaf

  The author of Lrama LALR parser generator. Ruby committer.

• 
  Yuji Yokoo

  @yujiyokoo

  Yuji is a software developer based in Tokyo, Japan. He was born and raised in Tokyo, spent over 2 decades in Adelaide, Australia, and has recently migrated back to Japan. He used to be a Windows desktop application developer until he discovered Ruby.

• 
  Yusuke Endoh

  @mametter

  'A full-time MRI committer at STORES, Inc. He has been interested in testing, analyzing, abusing of Ruby. He is an advocate of "transcendental programming" that creates a useless program like this bio. (_)'.yield_self{|s|eval(t=%q(puts"'#{s.sub(?_,?_+?_)}'.yield_self{|s|eval(t=%q(#{t}))}"))}

• 
  Yutaka HARA

  @yhara

  Rubyist since 2000 (Ruby 1.4.6). Works for Network Applied Communication Laboratory. Is not a Ruby committer.

• 
  Yuya Fujiwara

  @asonas

  I am Software engineer.