diff --git a/.hound.yml b/.hound.yml
new file mode 100644
index 0000000000..c67bfecae9
--- /dev/null
+++ b/.hound.yml
@@ -0,0 +1,3 @@
+ruby:
+  enabled: true
+  config_file: .rubocop.yml
\ No newline at end of file
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000000..a22df7c695
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,265 @@
+AllCops:
+  Exclude:
+    - *.gemspec
+
+AccessorMethodName:
+  Enabled: false
+
+ActionFilter:
+  Enabled: false
+
+Alias:
+  Enabled: false
+
+AndOr:
+  Enabled: false
+
+ArrayJoin:
+  Enabled: false
+
+AsciiComments:
+  Enabled: false
+
+AsciiIdentifiers:
+  Enabled: false
+
+Attr:
+  Enabled: false
+
+BlockNesting:
+  Enabled: false
+
+Blocks:
+  Enabled: false
+
+CaseEquality:
+  Enabled: false
+
+CharacterLiteral:
+  Enabled: false
+
+ClassAndModuleChildren:
+  Enabled: false
+
+ClassLength:
+  Enabled: false
+
+ClassVars:
+  Enabled: false
+
+CollectionMethods:
+  PreferredMethods:
+    find: detect
+    reduce: inject
+    collect: map
+    find_all: select
+
+ColonMethodCall:
+  Enabled: false
+
+CommentAnnotation:
+  Enabled: false
+
+CyclomaticComplexity:
+  Enabled: false
+
+Delegate:
+  Enabled: false
+
+DeprecatedHashMethods:
+  Enabled: false
+
+Documentation:
+  Enabled: false
+
+DotPosition:
+  EnforcedStyle: leading
+
+DoubleNegation:
+  Enabled: false
+
+EachWithObject:
+  Enabled: false
+
+EmptyLiteral:
+  Enabled: false
+
+Encoding:
+  Enabled: false
+
+EvenOdd:
+  Enabled: false
+
+FileName:
+  Enabled: false
+
+FlipFlop:
+  Enabled: false
+
+FormatString:
+  Enabled: false
+
+GlobalVars:
+  Enabled: false
+
+GuardClause:
+  Enabled: false
+
+IfUnlessModifier:
+  Enabled: false
+
+IfWithSemicolon:
+  Enabled: false
+
+InlineComment:
+  Enabled: false
+
+Lambda:
+  Enabled: false
+
+LambdaCall:
+  Enabled: false
+
+LineEndConcatenation:
+  Enabled: false
+
+LineLength:
+  Max: 100
+
+MethodLength:
+  Enabled: false
+
+ModuleFunction:
+  Enabled: false
+
+NegatedIf:
+  Enabled: false
+
+NegatedWhile:
+  Enabled: false
+
+Next:
+  Enabled: false
+
+NilComparison:
+  Enabled: false
+
+Not:
+  Enabled: false
+
+NumericLiterals:
+  Enabled: false
+
+OneLineConditional:
+  Enabled: false
+
+OpMethod:
+  Enabled: false
+
+ParameterLists:
+  Enabled: false
+
+PercentLiteralDelimiters:
+  Enabled: false
+
+PerlBackrefs:
+  Enabled: false
+
+PredicateName:
+  NamePrefixBlacklist:
+    - is_
+
+Proc:
+  Enabled: false
+
+RaiseArgs:
+  Enabled: false
+
+RegexpLiteral:
+  Enabled: false
+
+SelfAssignment:
+  Enabled: false
+
+SingleLineBlockParams:
+  Enabled: false
+
+SingleLineMethods:
+  Enabled: false
+
+SignalException:
+  Enabled: false
+
+SpecialGlobalVars:
+  Enabled: false
+
+StringLiterals:
+  EnforcedStyle: single_quotes
+
+VariableInterpolation:
+  Enabled: false
+
+TrailingComma:
+  Enabled: false
+
+TrivialAccessors:
+  Enabled: false
+
+VariableInterpolation:
+  Enabled: false
+
+WhenThen:
+  Enabled: false
+
+WhileUntilModifier:
+  Enabled: false
+
+WordArray:
+  Enabled: false
+
+# Lint
+
+AmbiguousOperator:
+  Enabled: false
+
+AmbiguousRegexpLiteral:
+  Enabled: false
+
+AssignmentInCondition:
+  Enabled: false
+
+ConditionPosition:
+  Enabled: false
+
+DeprecatedClassMethods:
+  Enabled: false
+
+ElseLayout:
+  Enabled: false
+
+HandleExceptions:
+  Enabled: false
+
+InvalidCharacterLiteral:
+  Enabled: false
+
+LiteralInCondition:
+  Enabled: false
+
+LiteralInInterpolation:
+  Enabled: false
+
+Loop:
+  Enabled: false
+
+ParenthesesAsGroupedExpression:
+  Enabled: false
+
+RequireParentheses:
+  Enabled: false
+
+UnderscorePrefixedVariableName:
+  Enabled: false
+
+Void:
+  Enabled: false
\ No newline at end of file
diff --git a/lib/open_project/auth_plugins.rb b/lib/open_project/auth_plugins.rb
index 68fa31071f..3ddb40b0ef 100644
--- a/lib/open_project/auth_plugins.rb
+++ b/lib/open_project/auth_plugins.rb
@@ -29,9 +29,9 @@
 
 module OpenProject
   module AuthPlugins
-    require "open_project/plugins/auth_plugin"
-    require "omniauth/flexible_builder"
-    require "omniauth/flexible_strategy"
-    require "open_project/auth_plugins/engine"
+    require 'open_project/plugins/auth_plugin'
+    require 'omniauth/flexible_builder'
+    require 'omniauth/flexible_strategy'
+    require 'open_project/auth_plugins/engine'
   end
 end
diff --git a/lib/open_project/auth_plugins/engine.rb b/lib/open_project/auth_plugins/engine.rb
index 59ef54a123..5a3ea8a087 100644
--- a/lib/open_project/auth_plugins/engine.rb
+++ b/lib/open_project/auth_plugins/engine.rb
@@ -36,8 +36,8 @@ module OpenProject::AuthPlugins
     include OpenProject::Plugins::ActsAsOpEngine
 
     register 'openproject-auth_plugins',
-             :author_url => 'http://finn.de',
-             :requires_openproject => '>= 3.1.0pre1'
+             author_url: 'http://finn.de',
+             requires_openproject: '>= 3.1.0pre1'
 
     initializer 'auth_plugins.register_hooks' do
       require 'open_project/auth_plugins/hooks'
diff --git a/lib/open_project/auth_plugins/hooks.rb b/lib/open_project/auth_plugins/hooks.rb
index 039bfce1da..9cd6797040 100644
--- a/lib/open_project/auth_plugins/hooks.rb
+++ b/lib/open_project/auth_plugins/hooks.rb
@@ -29,6 +29,6 @@
 
 module OpenProject::AuthPlugins
   class Hooks < Redmine::Hook::ViewListener
-    render_on :view_account_login_auth_provider, :partial => 'hooks/login/providers'
+    render_on :view_account_login_auth_provider, partial: 'hooks/login/providers'
   end
 end
diff --git a/lib/open_project/auth_plugins/version.rb b/lib/open_project/auth_plugins/version.rb
index cb2c3bb528..b64fbe4828 100644
--- a/lib/open_project/auth_plugins/version.rb
+++ b/lib/open_project/auth_plugins/version.rb
@@ -29,6 +29,6 @@
 
 module OpenProject
   module AuthPlugins
-    VERSION = "4.1.0"
+    VERSION = '4.1.0'
   end
 end
diff --git a/lib/open_project/plugins/auth_plugin.rb b/lib/open_project/plugins/auth_plugin.rb
index 467c8da0b7..f2e53e4ffb 100644
--- a/lib/open_project/plugins/auth_plugin.rb
+++ b/lib/open_project/plugins/auth_plugin.rb
@@ -47,20 +47,20 @@ module OpenProject::Plugins
     end
 
     def self.providers_for(strategy)
-      strategies[strategy_key(strategy)].map(&:call).flatten.map { |p| p.to_hash }
+      strategies[strategy_key(strategy)].map(&:call).flatten.map(&:to_hash)
     end
 
     def self.providers
-      strategies.values.flatten.map(&:call).flatten.map { |p| p.to_hash }
+      strategies.values.flatten.map(&:call).flatten.map(&:to_hash)
     end
 
     def self.strategy_key(strategy)
       return strategy if strategy.is_a? Symbol
 
       name = strategy.name.demodulize
-      camelization = OmniAuth.config.camelizations.select do |k, v|
+      camelization = OmniAuth.config.camelizations.select do |_k, v|
         v == name
-      end.take(1).map do |k, v|
+      end.take(1).map do |k, _v|
         k
       end.first
 
diff --git a/openproject-auth_plugins.gemspec b/openproject-auth_plugins.gemspec
index 7ca76a3f7b..a8d91c251f 100644
--- a/openproject-auth_plugins.gemspec
+++ b/openproject-auth_plugins.gemspec
@@ -1,22 +1,22 @@
 # encoding: UTF-8
-$:.push File.expand_path("../lib", __FILE__)
+$:.push File.expand_path('../lib', __FILE__)
 
 require 'open_project/auth_plugins/version'
 
 Gem::Specification.new do |s|
-  s.name        = "openproject-auth_plugins"
+  s.name        = 'openproject-auth_plugins'
   s.version     = OpenProject::AuthPlugins::VERSION
-  s.authors     = "Finn GmbH"
-  s.email       = "info@finn.de"
-  s.homepage    = "https://www.openproject.org/projects/auth-plugins"
+  s.authors     = 'Finn GmbH'
+  s.email       = 'info@finn.de'
+  s.homepage    = 'https://www.openproject.org/projects/auth-plugins'
   s.summary     = 'OpenProject Auth Plugins'
-  s.description = "Integration of OmniAuth strategy providers for authentication in Openproject."
-  s.license     = "GPLv3"
+  s.description = 'Integration of OmniAuth strategy providers for authentication in Openproject.'
+  s.license     = 'GPLv3'
 
-  s.files = Dir["{app,config,db,lib}/**/*"] + %w(doc/CHANGELOG.md README.md)
+  s.files = Dir['{app,config,db,lib}/**/*'] + %w(doc/CHANGELOG.md README.md)
 
-  s.add_dependency "rails", "~> 3.2.14"
-  s.add_dependency "omniauth", "~> 1.0"
+  s.add_dependency 'rails', '~> 3.2.14'
+  s.add_dependency 'omniauth', '~> 1.0'
 
-  s.add_development_dependency "rspec", "~> 2.14"
+  s.add_development_dependency 'rspec', '~> 2.14'
 end
diff --git a/spec/requests/auth_plugins.rb b/spec/requests/auth_plugins.rb
index 1f0f16ac3b..b8ec93dcce 100644
--- a/spec/requests/auth_plugins.rb
+++ b/spec/requests/auth_plugins.rb
@@ -37,13 +37,13 @@ describe OpenProject::Plugins::AuthPlugin do
 
   let(:strategies) { {} }
   let(:providers_a) do
-    lambda { [{name: 'a1'}, {name: 'a2'}] }
+    lambda { [{ name: 'a1' }, { name: 'a2' }] }
   end
   let(:providers_b) do
-    lambda { [{name: 'b1'}] }
+    lambda { [{ name: 'b1' }] }
   end
   let(:providers_c) do
-    lambda { [{name: 'c1'}] }
+    lambda { [{ name: 'c1' }] }
   end
 
   let(:middlewares) { [] }
@@ -56,7 +56,7 @@ describe OpenProject::Plugins::AuthPlugin do
       middlewares << strategy
     }
 
-    app.stub_chain(:config, :middleware, :use) { |mw, &block|
+    app.stub_chain(:config, :middleware, :use) { |_mw, &block|
       omniauth_builder.instance_eval(&block)
     }
 
diff --git a/spec/requests/flexible_strategy_spec.rb b/spec/requests/flexible_strategy_spec.rb
index 543d0875ae..41d9bf9fe7 100644
--- a/spec/requests/flexible_strategy_spec.rb
+++ b/spec/requests/flexible_strategy_spec.rb
@@ -38,16 +38,16 @@ describe OmniAuth::FlexibleStrategy do
     end
   end
 
-  def env_for(url, opts={})
+  def env_for(url, opts = {})
     Rack::MockRequest.env_for(url, opts).tap do |env|
       env['rack.session'] = {}
     end
   end
 
-  let(:app)        { ->(env) { [200, env, "ok"] } }
+  let(:app)        { ->(env) { [200, env, 'ok'] } }
   let(:middleware) { MockStrategy.new(app) }
-  let(:provider_a) { {name: 'provider_a', identifier: 'a'} }
-  let(:provider_b) { {name: 'provider_b', identifier: 'b'} }
+  let(:provider_a) { { name: 'provider_a', identifier: 'a' } }
+  let(:provider_b) { { name: 'provider_b', identifier: 'b' } }
 
   before do
     allow(OpenProject::Plugins::AuthPlugin).to receive(:providers_for).with(MockStrategy) {
@@ -67,7 +67,7 @@ describe OmniAuth::FlexibleStrategy do
     end
 
     it 'should not match other paths' do
-      code, env = middleware.call env_for("http://www.example.com/auth/other_provider")
+      code, env = middleware.call env_for('http://www.example.com/auth/other_provider')
 
       expect(env).not_to include 'omniauth.strategy' # no hit
     end
@@ -87,7 +87,7 @@ describe OmniAuth::FlexibleStrategy do
     end
 
     it 'should not match other paths' do
-      code, env = middleware.call env_for("http://www.example.com/auth/other_provider/callback")
+      code, env = middleware.call env_for('http://www.example.com/auth/other_provider/callback')
 
       expect(code).to eq 200
       expect(env).not_to include 'omniauth.strategy' # no hit
@@ -116,16 +116,16 @@ describe OmniAuth::FlexibleStrategy do
 
     context 'with a mapping set' do
       it 'returns an attribute hash' do
-        middleware.call env_for("http://www.example.com/auth/provider_with_mapping")
+        middleware.call env_for('http://www.example.com/auth/provider_with_mapping')
 
         attribute_map = middleware.omniauth_hash_to_user_attributes(auth_hash)
-        expect(attribute_map).to eq({ uid: 'foo', mail: 'foo@example.com' })
+        expect(attribute_map).to eq(uid: 'foo', mail: 'foo@example.com')
       end
     end
 
     context 'without a mapping set' do
       it 'returns an empty hash' do
-        middleware.call env_for("http://www.example.com/auth/provider_a")
+        middleware.call env_for('http://www.example.com/auth/provider_a')
 
         attribute_map = middleware.omniauth_hash_to_user_attributes(auth_hash)
         expect(attribute_map).to eq({})
diff --git a/spec/views/hooks/login/_providers.html.erb_spec.rb b/spec/views/hooks/login/_providers.html.erb_spec.rb
index 37c3b0afa6..60ea99e042 100644
--- a/spec/views/hooks/login/_providers.html.erb_spec.rb
+++ b/spec/views/hooks/login/_providers.html.erb_spec.rb
@@ -31,16 +31,16 @@ require 'spec_helper'
 describe 'rendering the login buttons for all providers' do
   let(:providers) do
     [
-      {name: 'mock_auth'},
-      {name: 'test_auth', display_name: 'Test'},
-      {name: 'foob_auth', icon: 'foobar.png'}
+      { name: 'mock_auth' },
+      { name: 'test_auth', display_name: 'Test' },
+      { name: 'foob_auth', icon: 'foobar.png' }
     ]
   end
 
   before do
     allow(OpenProject::Plugins::AuthPlugin).to receive(:providers).and_return(providers)
 
-    render :partial => 'hooks/login/providers', :handlers => [:erb], :formats => [:html]
+    render partial: 'hooks/login/providers', handlers: [:erb], formats: [:html]
   end
 
   it 'should show the mock_auth button with the name as its label' do