I'm Andi(@largo)! I like to automate things for myself and others, so I became a programmer! Please leave a comment or an issue if you try out any of my projects and cannot get it to work. I love meeting new people, say hello. お気軽にご連絡ください。

In January 2023 I wondered why require 'gtk3' took 3+ seconds on Windows. I traced it with Procmon and filed Bug #19378. The cause: Windows has no native realpath, so Ruby emulates it. Every require opened a handle on every parent directory of the file, and each open cost 8 syscalls. One file deep inside a gem (C:\Ruby32-x64\lib\ruby\gems\3.2.0\gems\glib2-4.0.8\lib\glib2\variant.rb) needed 80 syscalls, and the same work was repeated for every file.

In 2026 I tried GetFileInformationByName (Windows 11 24H2+), which gets the same information in one call, and attached a rough patch. Hiroshi Shibata did the careful part: he reworked it for ReFS, junctions and mount points, tested it thoroughly and merged it in ruby/ruby#18193. My original commit is part of it. In his benchmarks File.stat got about 3.9× faster and requiring big gems like rubocop or active_support 1.35–1.55× faster.

This should be in Ruby 4.1 this Christmas, so the short delay when a Ruby program starts on Windows gets noticeably shorter.

I also tried YJIT on Windows. It had never run there (#19325), and in August 2026 I got an experimental port working with a lot of help from AI. It mostly showed that it could be done. hsbt then wrote a proper implementation for mswin (ruby/ruby#19114), which passes the test suite and runs about 2× faster than the interpreter in his benchmarks. It is waiting for review now.

Thanks to nobu, hsbt and everyone who commented on these tickets over the years.

Ruby in the browser (ruby.wasm)

• Largo/chunkybacon: Learn Ruby in the browser with Chunky Bacon. An interactive notebook course in German and English, running on ruby.wasm.
• Largo/jsg: the jsg command creates, builds and serves ruby.wasm browser projects. Gem
• Largo/nokogiri-pure: Nokogiri 1.19.4 in pure Ruby. libxml2, libxslt and gumbo ported to Ruby, no C extension, so it runs on ruby.wasm. Gem
• Largo/bigdecimal-pure: BigDecimal in pure Ruby. require 'bigdecimal' still uses the native gem when it is available. Gem

Ruby + LLMs

• Largo/ruby_llm-claude_cli: use Claude Code and its subscription login as a RubyLLM provider. Streaming, images, PDFs, Office files, structured output and tool calls, no API key needed. Gem
• Largo/ruby_llm-providers-infomaniak: a RubyLLM provider for Infomaniak AI Tools (Swiss-hosted models). Gem

Office files

• Largo/ruby_pptx: a Ruby port of python-pptx. Create, read and update PowerPoint files. Gem

• IronRuby: Ruby for .NET. I forked IronRuby and got it to work with .NET 8 and 10 and made it Ruby 4.0 compatible.

• Largo/ocran: Turn Ruby Scripts into .exe files. Now with Linux and MacOS Support. Cosmopolitain LibC Support means that a simple Rails app can be shipped as an executable and will run everywhere.

• Largo/cosmoruby: Actually Portable Ruby Executables

• Largo/HacketyHack: HacketyHack working in 2026. Includes clogs, which runs Shoes programs on plain CRuby with native widgets (libui), no browser engine or JVM needed.

• I got Ruboto: Ruby on Android to work with JRuby 10 largo/ruboto. This means Ruby apps working on Android phones and WearOS.

• Working on Drivers and PHP internals.

• My friend Yosei Ito made a tool prremote to run mruby on Rasberry pi pico and ESP32s, which runs on the cmd line. It works very well with AI, because of it. I made inkmodoro as a demo for it.

• Faster require on Windows, and YJIT on Windows, see above.

• Historical Swiss Weather: see high/low temperatures on a map

  

• Ruby.wasm Template This is a template to start using Ruby.wasm in the browser.

• Largo/ruby.wasm-quickstart: Your ruby scripts in the browser

• Code for koans.idogawa.com

• Largo/glimmer-dsl-web-standalone-demo: This is a demo of Glimmer DSL for Web without rails. It allows you to use Ruby instead of JavaScript.

• 🔭 I’m currently working on improving Ruby for Windows. Checkout my ocra fork: ocran.

• 👯 I’m looking to collaborate on Ruby! I went to Ruby Kaigi 2024, Ruby World 2024 and Ruby Kaigi 2026. Ruby now works anywhere: Windows, OSX, Linux, Android and the browser! Let's make it even easier for everyone to use it! I'm looking forward to Ruby Kaigi 2027 in Miyazaki, Japan, which I recommended to the organizers.

• 🤔 Ruby on Windows can still get faster. Ideas are welcome!

• 💬 Ask me about anything Ruby! See my Ruby Gems

• 📫 How to reach me: see my email on my website!

• Talk to me in English, (Swiss-)German, Japanese or French!

• Favorite Editor: Micro and VSCode.

• DevOps: I've set up Devcontainers for VSCode so developers don't have to setup their own development environment. I self-host Gitlab.

• ⚡ Fun fact: My approach to development is inspired by Derek Sivers. Check out this cool podcast

Fields of interest: Ruby, MRuby / Picoruby, PHP, Python, JavaScript/Typescript, C/C++/C#, SaaS, VSCode Devcontainers, Docker, Self-hosting, crossplattform (Linux, Windows, MacOS), ecommerce, single developer projects, talking to people and helping them using code, simple solutions like htmx

• How to compile ruby on Windows and debug with GDB
• How to programm in Ruby on rails your phone or android tablet
• Edit your website on your android phone using termux and git!
• Taking Website Screenshots with Ruby
• How to git diff epub, docx and sqlite files
• Ruby on the frontend demo app
• Exploring the Dynamic World of Animated SVG Favicons