Ruby on Rails

Ruby on Rails is a full-stack web application framework that follows the Model-View-Controller (MVC) pattern. It provides everything needed to build database-backed web applications, from an ORM and a router to mailers, background jobs, WebSockets, file storage, and a CLI for generating new apps.

This wiki documents the source of the framework itself (the rails/rails monorepo), not the API for application developers. For application-level docs, see the Rails Guides and API documentation.

What lives in this repo

The repo is a monorepo of 12 independently-published Ruby gems. Each component has its own directory at the root and can be used outside Rails:

Component	Directory	One-line purpose
Active Support	activesupport/	Ruby core extensions, utilities, and infrastructure used by every other component
Active Model	activemodel/	Model interfaces (validations, callbacks, dirty tracking) without database dependence
Active Record	activerecord/	ORM and database abstraction layer
Action Pack	actionpack/	Routing, controllers, and HTTP request/response handling (Action Controller + Action Dispatch)
Action View	actionview/	Template rendering, ERB, and view helpers
Action Mailer	actionmailer/	Generating and sending email
Action Mailbox	actionmailbox/	Receiving and routing inbound email
Active Job	activejob/	Background job abstraction with pluggable queue adapters
Action Cable	actioncable/	WebSocket integration
Active Storage	activestorage/	File uploads to local disk or cloud storage
Action Text	actiontext/	Rich text content (Trix-backed)
Railties	railties/	The rails CLI, generators, application boot, and the glue that wires components together

The top-level rails gem (defined in rails.gemspec) simply depends on all 12 components at the same version.

Reading this wiki

If you're new to the codebase, start here:

1. Architecture — how the components fit together, the request lifecycle, and the boot process.
2. Getting started — clone, bootstrap, and run the test suite.
3. Glossary — the vocabulary used across the codebase.
4. Packages — drill into any single component.
5. How to contribute — workflow, testing, and conventions for sending PRs.

Project facts

• Current version (RAILS_VERSION on main): 8.2.0.alpha
• Required Ruby version: >= 3.3.1 (rails.gemspec)
• License: MIT (see MIT-LICENSE)
• First commit: November 24, 2004 (over 20 years of history; see lore)
• Total commits on main: ~97,500
• Test framework: Minitest (Rails does not use RSpec)
• Code style: RuboCop (see .rubocop.yml)

Where to look first

If you want to...	Start in
Understand how a request becomes a response	features/request-lifecycle
Understand how the rails CLI works	packages/railties
Find a model callback or validation	packages/active-model and packages/active-record
Add a database adapter	activerecord/lib/active_record/connection_adapters/
Add a queue adapter for background jobs	activejob/lib/active_job/queue_adapters/
Add a storage backend for uploads	activestorage/lib/active_storage/service/
Run tests for one component	how-to-contribute/testing

External links

• Project home: https://rubyonrails.org
• Issue tracker: https://github.com/rails/rails/issues
• Contributing guide: CONTRIBUTING.md
• Code of conduct: CODE_OF_CONDUCT.md
• Release process: RELEASING_RAILS.md