Ruby on Rails development and upgrades, from people who work on Ruby itself
We are a development company specializing in Ruby on Rails and Phoenix/Elixir. From new development to improving existing systems and technical consulting, we support your business with technology.
What We Do
From technology selection to development and operations, we support every phase of your project.
Rails and Ruby upgrades
Move an old Rails application to current Rails and Ruby step by step, without a rewrite and without stopping feature work. We start with a fixed-price roadmap.
Upgrade roadmap: $1,500
Ruby on Rails development
Small, well-defined Rails work at a fixed price: a first version of a new application, one feature, a fix, or monthly maintenance.
Feature or fix: from $1,000
Code audit and second opinion
An outside review of your Rails codebase, or of a proposal you have been given, written up in plain language so you can decide what to do next.
Second opinion: $500
JRuby and Java integration
Run Rails on the JVM, call Java libraries from Ruby, or embed Ruby in a Java system. We contribute to JRuby itself, so we can fix the problem where it starts.
JRuby assessment: from $2,000
Spinel: compile Ruby to native binaries
Spinel is Matz's new ahead-of-time compiler: it turns a subset of Ruby into a standalone native binary. We contribute to it, and we can tell you whether your code fits.
Feasibility study: $2,000
Our Products
As proof of our technical ability, we develop and operate our own products.
Japan Voyage
A platform for finding golf, ski and travel companions in Japan, plus rental homes for people moving here. Built with Rails 8, it implements real-time notifications, multilingual support, and map search.
japanvoyage.jp
From our blog
Notes on Ruby on Rails, Hotwire, and building web applications.
Moving Japan Voyage to JRuby, part 1: the fiber scheduler under Falcon
Japan Voyage runs on Falcon, which runs on Ruby's fiber scheduler. Before the app can boot on JRuby, that scheduler has to behave the way CRuby's does. This is what has been fixed in JRuby so far, and what is still in the way.
Rails 8アプリをRuby 4.0にアップグレードした
プロダクションのRails 8.1アプリをRuby 3.4から4.0にアップグレードした。意外とすんなりいった。
Rails 8でどうやってAlpineJSを導入できる？（importmap編）
Rails 8でもAlpineJS使いたいが、NPM/Yarn使わない場合、どうやって導入する？
Company Profile
- Company Name
- Sampo Development LLC
- Founded
- 2021
- Location
- Suita, Osaka, Japan
- Representative
- Kuokkanen Sampo
- Employees
- 2 people
- Languages
- Japanese, English, Chinese, Finnish
Strengths
- Extensive experience with real-time communication (WebSocket, ActionCable, Phoenix Channels).
- Able to develop and communicate in a multilingual environment (Japanese, English, Chinese).
- Consistent support from design through deployment and operation.
- Objective technical evaluation as a second opinion.
Team
Sampo Kuokkanen
Representative / CEO
A Ruby and Elixir developer from Finland, living in Japan. Representative of Sampo Development LLC and head of the Evil Martians GK Japan office. He is active in the Japanese Ruby community.
Speaking
- Kaigi on Rails 2023
- RubyWorld Conference 2024: “Keeping it Ruby: why your product need to have Ruby SDK”
- RubyConf Taiwan 2025: “What is happening with strings in Ruby and why is it feeling chilly?”
- COSCUP 2026: “Ruby on Ruby: ruby/spec, MRI tests, JRuby, and living on the edge”
Anssi Kuokkanen
Engineer
A Ruby on Rails engineer from Finland, living in Japan. He specializes in UX-focused web application development, handling everything from design to implementation. His motto is building products that balance usability and maintainability.
Education
- University of Helsinki, Graduate School: Master's degree
- Kobe University, Graduate School: Exchange program
Frequently Asked Questions
- What services does Sampo Development offer?
- New Ruby on Rails and Phoenix/Elixir application development, improving and scaling existing systems, code review, architecture design, security assessment, and second opinions.
- Do you work with clients outside Japan?
- Yes. We are based in Suita, Osaka, and work in English, Japanese, Chinese, and Finnish, collaborating with teams remotely worldwide.
- Which technologies do you specialize in?
- Ruby on Rails and Phoenix/Elixir, with deep experience in real-time, WebSocket-heavy systems built with Hotwire, ActionCable, and Phoenix Channels.
- Can you improve an existing application?
- Yes. We handle performance optimization, refactoring, new features, and technical consulting on the architecture and security of existing codebases.
- How much does it cost?
- We work on small, well-defined jobs at a fixed price, and each service page lists its prices. A second opinion is $500 and a Rails upgrade roadmap is $1,500.
- How do we get started?
- Send a few lines through the contact form, or email sampo@sampo.ltd. We reply within two business days to talk about your project and how we can help.
Feel Free to Get in Touch
Whether it's an upgrade, a small project, or a second opinion, tell us about it through the contact form or by email. We reply within two business days.