diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..00c33e4
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,88 @@
+AllCops:
+  TargetRubyVersion: 2.7.5
+  Exclude:
+    - 'frontend/node_modules/**/*'
+    - 'README.md'
+  NewCops: enable
+
+Bundler/OrderedGems:
+  Enabled: false
+
+Layout/DotPosition:
+  EnforcedStyle: leading
+
+Layout/LeadingCommentSpace:
+  Enabled: false
+
+Layout/MultilineMethodCallIndentation:
+  Enabled: false
+
+Layout/RescueEnsureAlignment:
+  Enabled: false
+
+Lint/EmptyBlock:
+  Enabled: false
+
+Lint/AmbiguousOperator:
+  Enabled: false
+
+Lint/NonLocalExitFromIterator:
+  Enabled: false
+
+Lint/ScriptPermission:
+  Enabled: false
+
+Metrics:
+  Enabled: false
+
+Naming/AccessorMethodName:
+  Enabled: false
+
+Naming/FileName:
+  Enabled: false
+
+Naming/PredicateName:
+  Enabled: false
+
+Naming/RescuedExceptionsVariableName:
+  Enabled: false
+
+Security:
+  Enabled: true
+
+Style/BlockDelimiters:
+  EnforcedStyle: braces_for_chaining
+
+Style/Documentation:
+  Enabled: false
+
+Style/NumericLiteralPrefix:
+  Enabled: false
+
+Style/NumericLiterals:
+  Enabled: false
+
+Style/PercentLiteralDelimiters:
+  PreferredDelimiters:
+    '%': ()
+    '%i': '[]'
+    '%I': '[]'
+    '%q': ()
+    '%Q': ()
+    '%r': '{}'
+    '%s': ()
+    '%w': '[]'
+    '%W': '[]'
+    '%x': ()
+
+Style/StringLiterals:
+  Enabled: false
+
+Style/StringLiteralsInInterpolation:
+  Enabled: false
+
+Style/TrailingCommaInArrayLiteral:
+  EnforcedStyleForMultiline: no_comma
+
+Style/TrailingCommaInHashLiteral:
+  EnforcedStyleForMultiline: no_comma
diff --git a/ruby/Gemfile b/ruby/Gemfile
index 27d1a7d..49b5949 100644
--- a/ruby/Gemfile
+++ b/ruby/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 gem 'sinatra'
@@ -10,4 +12,7 @@ gem 'mx-platform-ruby'
 group :test do
   # Test it with RSpec (BDD for Ruby)
   gem 'rspec-core'
+
+  # Keep files consistent
+  gem 'rubocop', require: false
 end
diff --git a/ruby/Gemfile.lock b/ruby/Gemfile.lock
index 83e6c32..534f29f 100644
--- a/ruby/Gemfile.lock
+++ b/ruby/Gemfile.lock
@@ -1,6 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    ast (2.4.2)
     dotenv (2.7.6)
     faraday (1.10.0)
       faraday-em_http (~> 1.0)
@@ -30,12 +31,30 @@ GEM
       ruby2_keywords (~> 0.0.1)
     mx-platform-ruby (0.11.2)
       faraday (~> 1.0, >= 1.0.1)
+    parallel (1.22.1)
+    parser (3.1.1.0)
+      ast (~> 2.4.1)
     rack (2.2.3)
     rack-protection (2.2.0)
       rack
+    rainbow (3.1.1)
+    regexp_parser (2.2.1)
+    rexml (3.2.5)
     rspec-core (3.11.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
+    rubocop (1.26.1)
+      parallel (~> 1.10)
+      parser (>= 3.1.0.0)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml
+      rubocop-ast (>= 1.16.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 3.0)
+    rubocop-ast (1.16.0)
+      parser (>= 3.1.1.0)
+    ruby-progressbar (1.11.0)
     ruby2_keywords (0.0.5)
     sinatra (2.2.0)
       mustermann (~> 1.0)
@@ -44,6 +63,7 @@ GEM
       tilt (~> 2.0)
     sinatra-cross_origin (0.3.2)
     tilt (2.0.10)
+    unicode-display_width (2.1.0)
 
 PLATFORMS
   x86_64-darwin-20
@@ -52,6 +72,7 @@ DEPENDENCIES
   dotenv (~> 2.7)
   mx-platform-ruby
   rspec-core
+  rubocop
   sinatra
   sinatra-cross_origin (~> 0.3.1)
 
diff --git a/ruby/app.rb b/ruby/app.rb
index f96c2b7..a72ea90 100644
--- a/ruby/app.rb
+++ b/ruby/app.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Load env vars from .env file
 require 'dotenv'
 Dotenv.load('./../.env')
@@ -43,7 +45,7 @@
 mx_platform_api = ::MxPlatformRuby::MxPlatformApi.new(api_client)
 
 get '/api/test' do
-  { :test => 'hit' }.to_json
+  { test: 'hit' }.to_json
 end
 
 get '/api/users' do
@@ -73,7 +75,7 @@ def create_user(user_id, mx_platform_api)
   content_type :json
 
   begin
-    request.body.rewind  # in case someone already read it
+    request.body.rewind # in case someone already read it
     data = JSON.parse(request.body.read)
     external_id = data['user_id'].empty? ? nil : data['user_id']
 
@@ -137,7 +139,7 @@ def create_user(user_id, mx_platform_api)
 post '/api/balances' do
   content_type :json
   begin
-    request.body.rewind  # in case someone already read it
+    request.body.rewind # in case someone already read it
     data = JSON.parse(request.body.read)
 
     response = mx_platform_api.check_balances(data['member_guid'], data['user_guid'])
diff --git a/ruby/spec/app_spec.rb b/ruby/spec/app_spec.rb
index 7e10fe0..22fc000 100644
--- a/ruby/spec/app_spec.rb
+++ b/ruby/spec/app_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe "app" do
   it 'should be implemented' do; end
 end
diff --git a/ruby/spec/spec_helper.rb b/ruby/spec/spec_helper.rb
index de9aa45..e570aab 100644
--- a/ruby/spec/spec_helper.rb
+++ b/ruby/spec/spec_helper.rb
@@ -1 +1,3 @@
-::Dir[File.expand_path("spec/**/*.rb")].each { |f| require f }
+# frozen_string_literal: true
+
+::Dir[File.expand_path("spec/**/*.rb")].sort.each { |f| require f }