A Ruby-based regular expression editor.

Inspired by: https://rubular.com

• Ruby 4.0

  Ruby 4.0 WASM builds require source patches and runtime workarounds. See WASM Build Notes for details.

• Ruby on Rails 8.1
• Regexp::Parser a regular expression parser library for Ruby

• Hotwire for building the frontend without using much JavaScript by sending HTML instead of JSON over the wire
• TailwindCSS to not have to write CSS at all
• RailroadDiagrams a tiny Ruby+SVG library for drawing railroad syntax diagrams like JSON.org

• Foreman for jsbundling-rails, cssbundling-rails
• Lefthook Fast and powerful Git hooks manager for any type of projects
• Dev Containers reproducible development environment via .devcontainer/
• Claude Code AI coding agent for development assistance

• Rubocop the Ruby Linter/Formatter that Serves and Protects
• ERB Lint Lint your ERB or HTML files
• Biome Format, lint, and more in a fraction of a second
• RSpec for Ruby testing
• Playwright for E2E testing
• Octocov octocov is a toolkit for collecting code metrics

• Wasmify Rails — Build Rails apps into WebAssembly so the application can run in the browser
• GitHub Pages — Host the generated static site (Wasm bundles and assets) as the deployment target

• Dependabot automated dependency updates built into GitHub
• Gitleaks Find secrets with Gitleaks
• Brakeman a static analysis security vulnerability scanner for Ruby on Rails applications

• GitHub Actions for testing, linting, and building web application and deploy to GitHub Pages

git clone https://github.com/aim2bpg/rubree.git
cd rubree
bin/setup

Then open http://localhost:3000 in your browser.

For Dev Container setup, linting, running tests against different browser drivers, and testing the WASM deployment locally, see Development Guide.

For an annotated walkthrough of every feature, see Usage Guide.

Rubree currently supports Chrome and Edge only.

Safari and Firefox have compatibility limitations with Ruby WebAssembly (Wasmify Rails):

• Safari: Ruby Wasm crashes during execution due to WebAssembly asyncify incompatibility

  • Error: RangeError: Maximum call stack size exceeded
  • The Ruby WebAssembly runtime crashes when trying to initialize Rails

• Firefox: Service Worker script evaluation fails

  • Error: TypeError: ServiceWorker script evaluation failed
  • The Service Worker script cannot be evaluated in Firefox's stricter module evaluation

These are fundamental limitations of how Safari and Firefox handle WebAssembly features required by Wasmify Rails. For more details, see wasmify-rails Issue #7.

When accessing Rubree from Safari or Firefox, you will see a warning banner with detailed console error logs for troubleshooting.

Rubree already covers the core editing/visualization/sharing experience — pattern matching, capture groups, railroad diagrams, substitution preview, Ruby code snippets, permalinks, and ReDoS checks. For the full feature checklist and the supported Regexp::Parser syntax scope used for railroad diagram generation, see Roadmap.

Bug reports and pull requests are welcome on GitHub at https://github.com/aim2bpg/rubree

This project is licensed under the MIT License, see the LICENSE file for details

• X (Twitter) — Launch announcement (2025-11-24)

  • https://x.com/aim2bpg/status/1992926501482983803

• はてなブログ — Ruby × Rails × Wasm で動く正規表現エディタ Rubree をリリースしました (2025-11-24)

  • https://aim2bpg.hatenablog.com/entry/2025/11/25/083000

• Qiita — Rubular を現代化した正規表現エディタ「Rubree」をリリースしました (2025-11-24)

  • https://qiita.com/aim2bpg/items/3190cf503456f231b78b

• DEV.to — Rubree: A Modern Ruby Regex Editor Running Fully in Your Browser (2025-11-24)

  • https://dev.to/aim2bpg/rubree-a-modern-ruby-regex-editor-running-fully-in-your-browser-5g2b

• Ruby Weekly #​777 (2025-11-27)

  • https://rubyweekly.com/issues/777#:~:text=Rubree

• 正規表現エディタ「Rubree」を紹介 - Railsチュートリアル note マガジン (2025-12-03)

  • https://note.com/yasslab/n/ncb57c9812545