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Contact me on Codementor

Hi, my name is 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 several 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

Pinned Loading

  1. alba Public

    Alba is the fastest JSON serializer for Ruby.

    Ruby 298 11

  2. Hook control for developers, by a developer

    Ruby 23

  3. Tutorials for learning Ruby

    Ruby 13

  4. Sensible default for RuboCop

    Ruby 6

  5. dotfiles Public

    Yet another dotfiles

    Shell 11

  6. Factory implementation for mruby

    Ruby 1

Contribution activity

November 2021

Created 1 repository

Created a pull request in rails/rails that received 2 comments

Add missing require for active_support/json to activesupport/lib/active_support/core_ext/object/json.rb

Summary This fixes a bug of missing require around ActiveSupport and JSON. To reproduce: irb(main):3.0.2:001:0> require 'active_support/core_ext/ob…

+1 −0 2 comments
Opened 3 other pull requests in 2 repositories
okuramasafumi/alba 2 merged
rubocop/rubocop 1 open

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