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@tekezo @bbatsov


Hi, my name OKURA Masafumi, a software developer based in Tokyo, Japan, focusing on Ruby/Rails.

What I've beed working on recently

  • I've beening developing a JSON Serializer for Ruby named Alba for a few months now. It provides a few DSL to organize JSON well and is the fastest among the alternatives.
  • I'm also organizing a large tech conference about Ruby on Rails called Kaigi on Rails. I'm the founder and chief organizer of the event. It starts this year (2020) and this time is the remote and domestic event for Japanese developers, but I'd like to make it an international one next year!
  • I started to organize a few Ruby meetups recently. One is Grow.rb and another is Entaku.rb. Grow.rb is a local meetup in Tokyo focusing on Ruby techniques but due to COVID-19 it's online from this spring. Entaku.rb is an online meetup from the beginning and is fosuing on discussions. I'm also a co-organizer of a few Ruby communities in Tokyo.
  • I traslated a book, Mastering Vim into Japanese.

What I'm going to do in the future

  • I love teaching. I've been a coach in Rails Girls for more than 10 times and now I'm going to have coaching sessions for more advanced developers. Visit the session page if you'd like to get one-to-one session to know more about Ruby and Rails.
  • I'd like to publish a book of my own. It'll be a book about Ruby on Rails and the basic of web technologies.
  • I think I need to learn a new programming language, but have not decided which one yet. Maybe Rust?


If you're interested to see a full list of links, visit my website.

Find my tweets (sorry but most of them are in Japanese) on


  1. Alba is the fastest JSON serializer for Ruby.

    Ruby 40

  2. neco is a NEo COmmand library

    Ruby 7 1

  3. Tutorials for learning Ruby

    Ruby 13

  4. Sensible default for RuboCop

    Ruby 5

  5. Yet another dotfiles

    Shell 11



Contribution activity

January 2021

Created 3 repositories

Created a pull request in rails/rails that received 1 comment

Warn when `:lower` is passed as a second arg of `ActiveSupport::Inflector.camelize`

Summary ActiveSupport::Inflector.camelize takes its second argument differently than String#camelize does. Some might pass :lower as a second argum…

+11 −0 1 comment
Opened 5 other pull requests in 5 repositories
1 merged
1 merged
1 open
1 merged
1 open

Created an issue in ruby/typeprof that received 1 comment

Print "generated by TypeProf" in the head of output with timestamp

It would be good to have something like "generated by TypeProf version 0.12.0 at 2021-01-04 00:53:00" in the head of output. This is similar to wha…

1 comment

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