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IRuby is a Ruby kernel for Jupyter project.

Try IRuby

You can try IRuby with a sample notebook on Binder (the same link as the banner placed above):

The following URL launches JupyterLab directly on Binder.



The following requirements are automatically installed.

The following dependencies are optional.

  • Pry, if you want to use Pry instead of IRB for the code execution backend

Installing Jupyter Notebook and/or JupyterLab

See the official document to know how to install Jupyter Notebook and/or JupyterLab.


Ubuntu 17+

sudo apt install libtool libffi-dev ruby ruby-dev make

gem install --user-install iruby
iruby register --force

Ubuntu 16

The latest IRuby requires Ruby >= 2.4 while Ubuntu's official Ruby package is version 2.3. So you need to install Ruby >= 2.4 by yourself before preparing IRuby. We recommend to use rbenv.

sudo apt install libtool libffi-dev ruby ruby-dev make
gem install --user-install iruby
iruby register --force


DevKit is necessary for building RubyGems with native C-based extensions.

gem install iruby
iruby register --force


Install ruby with rbenv or rvm. Install Jupyter.


gem install iruby
iruby register --force


If you are using macports, run the following commands.

port install libtool autoconf automake autogen
gem install iruby
iruby register --force


Try RubyData Docker Stacks. Running jupyter notebook:

docker run --rm -it -p 8888:8888 rubydata/datascience-notebook

Installation for JRuby

You can use Java classes in your IRuby notebook.

  • JRuby version >=
  • iruby gem

After installation, make sure that your env is set up to use jruby.

$ env ruby -v

If you use RVM, it is enough to switch the current version to jruby.

If you have already used IRuby with a different version, you need to generate a new kernel:

$ iruby register --force

Install the development version of IRuby

Be careful to use the development version because it is usually unstable.

If you want to install the development version of IRuby from the source code, try specific_install.

gem specific_install

Note for using with CZTop and CZMQ

CZTop adapter has been deprecated since IRuby version 0.7.4. It will be removed after several versions.

If you want to use IRuby with CZTop, you need to install it and CZMQ.

If both ffi-rzmq and cztop are installed, ffi-rzmq is used. If you prefer cztop, set the following environment variable.



There are two backends: PlainBackend and PryBackend.

  • PlainBackend is the default backend. It uses IRB.
  • PryBackend uses Pry.

You can switch the backend to PryBackend by running the code below.



Take a look at the example notebook and the collection of notebooks which includes a Dockerfile to create a containerized installation of iruby and other scientific gems. You can find the prebuild image at dockerhub.


Contributions to IRuby are very welcome.

To former contributors

In February 2021, IRuby became the canonical repository and is no longer a fork from minrk/iruby. Please fork from this repository again before making pull requests.


Copyright (c) IRuby contributors and the Ruby Science Foundation.

Licensed under the MIT license.