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A Ruby static code analyzer and formatter, based on the community Ruby style guide.
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koic Merge pull request #6859 from koic/fix_incorrect_autocorrect_for_lint…

[Fix #6858] Fix an incorrect auto-correct for `Lint/ToJSON`
Latest commit 86f35b2 Mar 24, 2019
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.circleci Remove unnecessary Ruby version specification on CI Dec 29, 2018
assets Change organization URL to rubocop-hq May 31, 2018
bin Add `bin/setup` script to bin dir Jun 17, 2018
config [Fix #6393] Add AllowBracesOnProceduralOneLiners option to Style/Bloc… Mar 17, 2019
logo [Fix #578] Add a logo Sep 4, 2014
manual [Fix #6858] Fix an incorrect auto-correct for `Lint/ToJSON` Mar 23, 2019
spec [Fix #6858] Fix an incorrect auto-correct for `Lint/ToJSON` Mar 23, 2019
tasks We want the runner to not exit when done Oct 31, 2018
.editorconfig Add an `.editorconfig` file (#3748) Dec 1, 2016
.rubocop.yml Exclude gemspec file by default for `Metrics/BlockLength` Mar 5, 2019
.rubocop_todo.yml Add new RangeNode extension Jan 8, 2019
.simplecov Generate code coverage report on all spec runs Sep 11, 2018
.yardopts Hide void return of methods in YARD documentation Jun 10, 2013 [Fix #6858] Fix an incorrect auto-correct for `Lint/ToJSON` Mar 23, 2019
LICENSE.txt Cut 0.66 Mar 18, 2019
Rakefile Generate code coverage report on all spec runs Sep 11, 2018
appveyor.yml Drop old Ruby version matrix from Appveyor CI Jan 30, 2019
rubocop.gemspec [#5977] Warn for Performance Cops Mar 19, 2019

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RuboCop Logo

Role models are important.
-- Officer Alex J. Murphy / RoboCop

RuboCop is a Ruby static code analyzer and code formatter. Out of the box it will enforce many of the guidelines outlined in the community Ruby Style Guide.

RuboCop is extremely flexible and most aspects of its behavior can be tweaked via various configuration options.

Apart from reporting problems in your code, RuboCop can also automatically fix some of the problems for you.


Please consider financially supporting its ongoing development.


RuboCop's installation is pretty standard:

$ gem install rubocop

If you'd rather install RuboCop using bundler, don't require it in your Gemfile:

gem 'rubocop', require: false

RuboCop's development is moving at a very rapid pace and there are often backward-incompatible changes between minor releases (since we haven't reached version 1.0 yet). To prevent an unwanted RuboCop update you might want to use a conservative version lock in your Gemfile:

gem 'rubocop', '~> 0.66.0', require: false


Just type rubocop in a Ruby project's folder and watch the magic happen.

$ cd my/cool/ruby/project
$ rubocop

Official manual

You can read a ton more about RuboCop in its official manual.


RuboCop supports the following Ruby implementations:

  • MRI 2.2+
  • JRuby 9.0+

The Rails cops support the following versions:

  • Rails 4.0+


Here's a list of RuboCop's core developers:


RuboCop's logo was created by Dimiter Petrov. You can find the logo in various formats here.

The logo is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.


Here's a list of all the people who have contributed to the development of RuboCop.

I'm extremely grateful to each and every one of them!

If you'd like to contribute to RuboCop, please take the time to go through our short contribution guidelines.

Converting more of the Ruby Style Guide into RuboCop cops is our top priority right now. Writing a new cop is a great way to dive into RuboCop!

Of course, bug reports and suggestions for improvements are always welcome. GitHub pull requests are even better! :-)


While RuboCop is free software and will always be, the project would benefit immensely from some funding. Raising a monthly budget of a couple of thousand dollars would make it possible to pay people to work on certain complex features, fund other development related stuff (e.g. hardware, conference trips) and so on. Raising a monthly budget of over $5000 would open the possibility of someone working full-time on the project which would speed up the pace of development significantly.

We welcome both individual and corporate sponsors! We also offer a wide array of funding channels to account for your preferences (although currently Open Collective is our preferred funding platform).

If you're working in a company that's making significant use of RuboCop we'd appreciate it if you suggest to your company to become a RuboCop sponsor.

You can support the development of RuboCop via Salt, Patreon, Liberapay, and Open Collective.

Open Collective Backers

Support us with a monthly donation and help us continue our activities. [Become a backer]

Open Collective Sponsors

Become a sponsor and get your logo on our README on GitHub with a link to your site. [Become a sponsor]


RuboCop's changelog is available here.


Copyright (c) 2012-2019 Bozhidar Batsov. See LICENSE.txt for further details.

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