Ruby Playground

Ruby Playground is a free website for writing and running Ruby in your browser: https://ruby-play.dev/. Type Ruby in the editor and the output updates as you edit. You can switch between Ruby versions and share code by copying the URL. No installation or account is required. Ruby runs inside the browser with ruby.wasm, so your code is not sent to a server to be executed.

The site also includes a step-by-step Ruby tutorial whose lessons run code in the page.

Features

• Live execution. Code runs shortly after you stop typing. Standard output, standard error and exceptions appear in the Output panel as plain text. Use puts or p to print values; expression return values are not shown automatically.
• Ruby versions. Choose from several Ruby versions, including a development snapshot. The selector shows the exact bundled patch version, and a panel shows the running VM's version, platform, encoding, release date and revision.
• Sharing by URL. The code and selected version are saved in the address bar as you edit. Copy the URL to share an example or bookmark it. Opening a shared link restores the code and runs it.
• Ruby tutorial. Lessons are grouped into chapters, from the basics to classes and more advanced syntax. Each lesson has an explanation, an example and experiments to run and edit. Each Ruby version has its own course at /tutorial/{version}/.
• Light and dark themes. The theme follows your system setting, and a theme you choose is remembered across reloads.

Limitations

• Programs are single files. Standard input (gets), Rails, additional gems and saved snippets are not supported.
• Each run starts in a new Ruby VM, so variables, constants and files from earlier runs are not kept.
• Run time, output size, code length and share URL length are limited. The page shows a message when a limit is reached. Code that is too long for the URL still runs but is not saved in the URL.
• The first run downloads the selected runtime, which is tens of megabytes, and can be slow on a slow connection.
• The runtimes are official ruby.wasm builds. They can be older than the latest Ruby patch releases and can lack recent security fixes. The selector shows the exact patch version.

Security and privacy

• Code runs in your browser in a Web Worker. Each run uses a new Worker and Ruby VM, and Ruby's JavaScript bridge is disabled. The Worker keeps the page responsive and separates runs, but it is not a security sandbox for hostile code. Run only code you trust.
• Shared links run automatically when opened, and the URL contains the full source code. Do not open links from sources you do not trust, and keep passwords and personal information out of your code. Because the code is part of the URL, it can remain in browser history and in hosting request logs.
• The site is a static site on GitHub Pages. There are no accounts and no application backend, and the site uses no analytics or advertising. See the privacy policy.

Feedback and contributing

Report bugs and request features in GitHub issues or by DM to @glassmonekey. For local setup, tests, deployment and tutorial authoring, see docs/contributing.md.

You can support the project through GitHub Sponsors.

License

Apache License 2.0. See LICENSE and NOTICE. The build configuration is adapted from php-playground. License notices for Ruby and ruby.wasm are in assets/licenses/.