diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..bd5de2b
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,203 @@
+AllCops:
+  Include:
+    - lib/**/*.rb
+  TargetRubyVersion: 2.3
+
+
+Metrics/LineLength:
+  Max: 110 # Preferred length is 100
+
+Metrics/ParameterLists:
+  CountKeywordArgs: false
+  Max: 8
+
+Metrics/BlockLength:
+  Enabled: false
+
+Metrics/MethodLength:
+  Enabled: false
+
+Metrics/ClassLength:
+  Enabled: false
+
+Metrics/ModuleLength:
+  Enabled: false
+
+Metrics/AbcSize:
+  Enabled: false
+
+Metrics/CyclomaticComplexity:
+  Enabled: false
+
+Metrics/PerceivedComplexity:
+  Enabled: false
+
+Metrics/BlockNesting:
+  Max: 5
+
+
+Style/Encoding:
+  Enabled: false
+
+Style/StringLiterals:
+  Enabled: false # we don't care
+
+Style/RegexpLiteral:
+  AllowInnerSlashes: true
+
+Style/NumericLiterals:
+  MinDigits: 6
+
+Style/NumericLiteralPrefix:
+  EnforcedOctalStyle: zero_only
+
+Style/SymbolArray:
+  EnforcedStyle: brackets
+
+Style/WordArray:
+  MinSize: 5
+
+Style/TrailingCommaInArrayLiteral:
+  EnforcedStyleForMultiline: comma
+
+Style/TrailingCommaInHashLiteral:
+  EnforcedStyleForMultiline: comma
+
+Style/ClassCheck:
+  EnforcedStyle: kind_of?
+
+Style/EmptyMethod:
+  EnforcedStyle: expanded
+
+Style/Lambda:
+  EnforcedStyle: lambda
+
+Style/NumericPredicate:
+  EnforcedStyle: comparison
+
+Style/TernaryParentheses:
+  EnforcedStyle: require_parentheses
+
+Style/FormatString:
+  EnforcedStyle: sprintf
+
+Style/Semicolon:
+  AllowAsExpressionSeparator: true
+
+Style/YodaCondition:
+  EnforcedStyle: equality_operators_only
+
+Style/EmptyElse:
+  EnforcedStyle: empty
+
+
+Style/GuardClause:
+  Enabled: false # false alarms
+
+Style/MethodMissingSuper:
+  Enabled: false # why the need to fallback to super?
+
+Style/Next:
+  Enabled: false # not really useful
+
+Style/ParallelAssignment:
+  Enabled: false # not really needed
+
+Style/TrivialAccessors:
+  Enabled: false
+
+Style/NestedTernaryOperator:
+  Enabled: false # compact nested ternary operators are okay
+
+Style/RescueModifier:
+  Enabled: false # valid but using it makes life sometimes easier
+
+Style/MutableConstant:
+  Enabled: false # valid but sometimes unavoidable
+
+Style/CommentedKeyword:
+  Enabled: false # false alarms and we do want yield comments on that line
+
+Style/StderrPuts:
+  Enabled: false # false alarms because not all $stderr.puts messages are Ruby style warnings
+
+Style/PerlBackrefs:
+  Enabled: false # sometimes there are no good alternatives
+
+Style/IfUnlessModifier:
+  Enabled: false # useful but sometimes the meaning is better conveyed using an if/unless statement
+
+Style/InfiniteLoop:
+  Enabled: false # why should Kernel#loop be better than while true?
+
+Style/SpecialGlobalVars:
+  Enabled: false # I think that $! and $? are recognizable in terms of their function
+
+Style/MultipleComparison:
+  Enabled: false # why should an array be created? especially if only two items are compared
+
+Style/AccessModifierDeclarations:
+  Enabled: false
+
+Style/WhileUntilModifier:
+  Enabled: false # I prefer to use either one or the other, depending on context
+
+Style/FormatStringToken:
+  Enabled: false # I don't care about this
+
+Style/ClassAndModuleChildren:
+  Enabled: false
+
+
+Layout/AlignHash:
+  EnforcedLastArgumentHashStyle: ignore_implicit
+
+Layout/SpaceInsideBlockBraces:
+  SpaceBeforeBlockParameters: false
+
+Layout/SpaceInsideHashLiteralBraces:
+  EnforcedStyle: no_space
+
+Layout/EmptyLineBetweenDefs:
+  AllowAdjacentOneLineDefs: true
+
+Layout/EmptyLinesAroundModuleBody:
+  Enabled: false
+
+Layout/EmptyLinesAroundClassBody:
+  EnforcedStyle: empty_lines
+
+Layout/MultilineOperationIndentation:
+  EnforcedStyle: indented
+
+Layout/MultilineMethodCallIndentation:
+  EnforcedStyle: indented
+
+Layout/DotPosition:
+  EnforcedStyle: trailing
+
+Layout/EmptyLineAfterMagicComment:
+  Enabled: false # we have the magic comment and then the license
+
+Layout/IndentAssignment:
+  Enabled: false # false alarms
+
+
+Naming/HeredocDelimiterNaming:
+  Enabled: false # we like our delimiters short and obvious
+
+Naming/UncommunicativeMethodParamName:
+  Enabled: false # for points the names x,y are perfectly reasonable
+
+Lint/LiteralAsCondition:
+  Enabled: false # we use while true
+
+Lint/NonLocalExitFromIterator:
+  Enabled: false
+
+Performance/FixedSize:
+  Enabled: false
+
+
+Security/Open:
+  Enabled: false
diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..1bce8bb
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,21 @@
+kramdown-syntax-coderay
+Copyright (C) 2019 Thomas Leitner <t_leitner@gmx.at>
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..799c3bf
--- /dev/null
+++ b/README.md
@@ -0,0 +1,36 @@
+# kramdown syntax highlighter based on Coderay
+
+This is a syntax highlighter for [kramdown](https://kramdown.gettalong.org)
+that uses [coderay](http://coderay.rubychan.de/) to highlight code blocks and
+spans when converting to HTML.
+
+Note: Until kramdown version 2.0.0 this math engine was part of the kramdown
+distribution.
+
+
+## Installation
+
+~~~ruby
+gem install kramdown-syntax-coderay
+~~~
+
+
+## Usage
+
+~~~ruby
+require 'kramdown'
+require 'kramdown-syntax-coderay'
+
+Kramdown::Document.new(text, syntax_highlighter: :coderay).to_html
+~~~
+
+
+## Development
+
+Clone the git repository and you are good to go. You probably want to install
+`rake` so that you can use the provided rake tasks.
+
+
+## License
+
+MIT - see the **COPYING** file.
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..bb13c90
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,73 @@
+# -*- ruby -*-
+
+require 'rubygems/package_task'
+require 'fileutils'
+require 'rake/clean'
+require 'rake/testtask'
+require_relative 'lib/kramdown/converter/syntax_highlighter/coderay'
+
+task :default => :test
+Rake::TestTask.new do |test|
+  test.warning = false
+  test.libs << 'test'
+  test.test_files = FileList['test/test_*.rb']
+end
+
+SUMMARY = 'kramdown-syntax-coderay uses coderay to highlight code blocks/spans'
+
+PKG_FILES = FileList.new(['COPYING', 'VERSION', 'CONTRIBUTERS', 'lib/**/*.rb', 'test/**/*'])
+
+CLOBBER << "VERSION"
+file 'VERSION' do
+  puts "Generating VERSION file"
+  File.open('VERSION', 'w+') {|file| file.write(Kramdown::Converter::SyntaxHighlighter::Coderay::VERSION + "\n")}
+end
+
+CLOBBER << 'CONTRIBUTERS'
+file 'CONTRIBUTERS' do
+  puts "Generating CONTRIBUTERS file"
+  `echo "  Count Name" > CONTRIBUTERS`
+  `echo "======= ====" >> CONTRIBUTERS`
+  `git log | grep ^Author: | sed 's/^Author: //' | sort | uniq -c | sort -nr >> CONTRIBUTERS`
+end
+
+spec = Gem::Specification.new do |s|
+  s.name = 'kramdown-syntax-coderay'
+  s.version = Kramdown::Converter::SyntaxHighlighter::Coderay::VERSION
+  s.summary = SUMMARY
+  s.license = 'MIT'
+
+  s.files = PKG_FILES.to_a
+
+  s.require_path = 'lib'
+  s.required_ruby_version = '>= 2.3'
+  s.add_dependency 'kramdown', '~> 2.0'
+  s.add_dependency 'coderay', '~> 1.0.0'
+
+  s.has_rdoc = true
+
+  s.author = 'Thomas Leitner'
+  s.email = 't_leitner@gmx.at'
+  s.homepage = "https://github.com/kramdown/syntax-coderay"
+end
+
+Gem::PackageTask.new(spec) do |pkg|
+  pkg.need_zip = true
+  pkg.need_tar = true
+end
+
+task :gemspec => ['CONTRIBUTERS', 'VERSION'] do
+  print "Generating Gemspec\n"
+  contents = spec.to_ruby
+  File.write("kramdown-syntax-coderay.gemspec", contents, mode: 'w+')
+end
+CLOBBER << 'kramdown-syntax-coderay.gemspec'
+
+desc 'Release version ' + Kramdown::Converter::SyntaxHighlighter::Coderay::VERSION
+task :release => [:clobber, :package, :publish_files]
+
+desc "Upload the release to Rubygems"
+task :publish_files => [:package] do
+  sh "gem push pkg/kramdown-syntax-coderay-#{Kramdown::Converter::SyntaxHighlighter::Coderay::VERSION}.gem"
+  puts 'done'
+end
diff --git a/lib/kramdown-syntax-coderay.rb b/lib/kramdown-syntax-coderay.rb
new file mode 100644
index 0000000..647fda9
--- /dev/null
+++ b/lib/kramdown-syntax-coderay.rb
@@ -0,0 +1,10 @@
+# -*- coding: utf-8; frozen_string_literal: true -*-
+#
+#--
+# Copyright (C) 2019 Thomas Leitner <t_leitner@gmx.at>
+#
+# This file is part of kramdown-syntax-coderay which is licensed under the MIT.
+#++
+#
+
+require 'kramdown/converter/syntax_highlighter/coderay'
diff --git a/lib/kramdown/converter/syntax_highlighter/coderay.rb b/lib/kramdown/converter/syntax_highlighter/coderay.rb
new file mode 100644
index 0000000..447775f
--- /dev/null
+++ b/lib/kramdown/converter/syntax_highlighter/coderay.rb
@@ -0,0 +1,169 @@
+# -*- coding: utf-8; frozen_string_literal: true -*-
+#
+#--
+# Copyright (C) 2019 Thomas Leitner <t_leitner@gmx.at>
+#
+# This file is part of kramdown-syntax-coderay which is licensed under the MIT.
+#++
+#
+
+require 'kramdown/options'
+require 'kramdown/converter'
+require 'coderay'
+
+module Kramdown #:nodoc:
+
+  module Options #:nodoc:
+
+    define(:enable_coderay, Boolean, true, <<EOF)
+Use coderay for syntax highlighting
+
+If this option is `true`, coderay is used by the HTML converter for
+syntax highlighting the content of code spans and code blocks.
+
+Default: true
+Used by: HTML converter
+EOF
+
+    define(:coderay_wrap, Symbol, :div, <<EOF)
+Defines how the highlighted code should be wrapped
+
+The possible values are :span, :div or nil.
+
+Default: :div
+Used by: HTML converter
+EOF
+
+    define(:coderay_line_numbers, Symbol, :inline, <<EOF)
+Defines how and if line numbers should be shown
+
+The possible values are :table, :inline or nil. If this option is
+nil, no line numbers are shown.
+
+Default: :inline
+Used by: HTML converter
+EOF
+
+    define(:coderay_line_number_start, Integer, 1, <<EOF)
+The start value for the line numbers
+
+Default: 1
+Used by: HTML converter
+EOF
+
+    define(:coderay_tab_width, Integer, 8, <<EOF)
+The tab width used in highlighted code
+
+Used by: HTML converter
+EOF
+
+    define(:coderay_bold_every, Object, 10, <<EOF) do |val|
+Defines how often a line number should be made bold
+
+Can either be an integer or false (to turn off bold line numbers
+completely).
+
+Default: 10
+Used by: HTML converter
+EOF
+      if val == false || val.to_s == 'false'
+        false
+      else
+        Integer(val.to_s) rescue raise Kramdown::Error, "Invalid value for option 'coderay_bold_every'"
+      end
+    end
+
+    define(:coderay_css, Symbol, :style, <<EOF)
+Defines how the highlighted code gets styled
+
+Possible values are :class (CSS classes are applied to the code
+elements, one must supply the needed CSS file) or :style (default CSS
+styles are directly applied to the code elements).
+
+Default: style
+Used by: HTML converter
+EOF
+
+    define(:coderay_default_lang, Symbol, nil, <<EOF)
+Sets the default language for highlighting code blocks
+
+If no language is set for a code block, the default language is used
+instead. The value has to be one of the languages supported by coderay
+or nil if no default language should be used.
+
+Default: nil
+Used by: HTML converter
+EOF
+
+  end
+
+  module Converter #:nodoc:
+    module SyntaxHighlighter #:nodoc:
+
+      # Uses Coderay to highlight code blocks and code spans.
+      module Coderay
+
+        VERSION = '1.0.0'
+
+        def self.call(converter, text, lang, type, call_opts)
+          return nil unless converter.options[:enable_coderay]
+          if type == :span && lang
+            ::CodeRay.scan(text, lang.to_sym).html(options(converter, :span)).chomp
+          elsif type == :block && (lang || options(converter, :default_lang))
+            lang ||= call_opts[:default_lang] = options(converter, :default_lang)
+            ::CodeRay.scan(text, lang.to_s.tr('-', '_').to_sym).html(options(converter, :block)).chomp << "\n"
+          else
+            nil
+          end
+        rescue StandardError
+          converter.warning("There was an error using CodeRay: #{$!.message}")
+          nil
+        end
+
+        def self.options(converter, type)
+          prepare_options(converter)
+          converter.data[:syntax_highlighter_coderay][type]
+        end
+
+        def self.prepare_options(converter)
+          return if converter.data.key?(:syntax_highlighter_coderay)
+
+          cache = converter.data[:syntax_highlighter_coderay] = {}
+
+          opts = converter.options[:syntax_highlighter_opts].dup
+          span_opts = (opts.delete(:span) || {}).dup
+          block_opts = (opts.delete(:block) || {}).dup
+          [span_opts, block_opts].each do |hash|
+            hash.keys.each do |k|
+              hash[k.kind_of?(String) ? ::Kramdown::Options.str_to_sym(k) : k] = hash.delete(k)
+            end
+          end
+
+          cache[:default_lang] = converter.options[:coderay_default_lang] || opts.delete(:default_lang)
+          cache[:span] = {
+            css: converter.options[:coderay_css],
+          }.update(opts).update(span_opts).update(wrap: :span)
+          cache[:block] = {
+            wrap: converter.options[:coderay_wrap],
+            line_numbers: converter.options[:coderay_line_numbers],
+            line_number_start: converter.options[:coderay_line_number_start],
+            tab_width: converter.options[:coderay_tab_width],
+            bold_every: converter.options[:coderay_bold_every],
+            css: converter.options[:coderay_css],
+          }.update(opts).update(block_opts)
+
+          [:css, :wrap, :line_numbers].each do |key|
+            [:block, :span].each do |type|
+              cache[type][key] = cache[type][key].to_sym if cache[type][key].kind_of?(String)
+            end
+          end
+        end
+
+      end
+    end
+
+    add_syntax_highlighter(:coderay, SyntaxHighlighter::Coderay)
+
+  end
+
+end
diff --git a/test/test_files.rb b/test/test_files.rb
new file mode 100644
index 0000000..59e3ea3
--- /dev/null
+++ b/test/test_files.rb
@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+#
+#--
+# Copyright (C) 2019 Thomas Leitner <t_leitner@gmx.at>
+#
+# This file is part of kramdown-syntax-coderay which is licensed under the MIT.
+#++
+#
+
+require 'minitest/autorun'
+require 'kramdown'
+require 'kramdown-syntax-coderay'
+require 'yaml'
+require 'tmpdir'
+
+Encoding.default_external = 'utf-8'
+
+class TestFiles < Minitest::Test
+
+  Dir[File.dirname(__FILE__) + '/testcases/**/*.text'].each do |text_file|
+    basename = text_file.sub(/\.text$/, '')
+
+    html_file = basename + '.html'
+    define_method('test_' + text_file.tr('.', '_') + "_to_html") do
+      opts_file = basename + '.options'
+      opts_file = File.join(File.dirname(html_file), 'options') if !File.exist?(opts_file)
+      options = File.exist?(opts_file) ? YAML::load(File.read(opts_file)) : {auto_ids: false, footnote_nr: 1}
+      doc = Kramdown::Document.new(File.read(text_file), options)
+      assert_equal(File.read(html_file), doc.to_html)
+    end
+  end
+
+end
diff --git a/test/testcases/highlighting-opts.html b/test/testcases/highlighting-opts.html
new file mode 100644
index 0000000..5a2ea48
--- /dev/null
+++ b/test/testcases/highlighting-opts.html
@@ -0,0 +1,6 @@
+<div class="language-ruby highlighter-coderay"><span class="CodeRay">x = <span class="constant">Class</span>.new
+</span>
+</div>
+<div class="language-html highlighter-coderay"><span class="CodeRay"><span class="tag">&lt;a&gt;</span>href<span class="tag">&lt;/a&gt;</span>
+</span>
+</div>
diff --git a/test/testcases/highlighting-opts.options b/test/testcases/highlighting-opts.options
new file mode 100644
index 0000000..0e04a45
--- /dev/null
+++ b/test/testcases/highlighting-opts.options
@@ -0,0 +1,8 @@
+:syntax_highlighter: :coderay
+:syntax_highlighter_opts:
+  block:
+    css: class
+  default_lang: ruby
+  wrap: span
+  line_numbers: null
+
diff --git a/test/testcases/highlighting-opts.text b/test/testcases/highlighting-opts.text
new file mode 100644
index 0000000..5ac4746
--- /dev/null
+++ b/test/testcases/highlighting-opts.text
@@ -0,0 +1,4 @@
+    x = Class.new
+^
+    <a>href</a>
+{: .language-html}
diff --git a/test/testcases/highlighting-span.html b/test/testcases/highlighting-span.html
new file mode 100644
index 0000000..c6860f6
--- /dev/null
+++ b/test/testcases/highlighting-span.html
@@ -0,0 +1 @@
+<p>You can say <code class="language-ruby highlighter-coderay"><span class="CodeRay">x = <span style="color:#036;font-weight:bold">Class</span>.new</span></code>, for example.</p>
diff --git a/test/testcases/highlighting-span.options b/test/testcases/highlighting-span.options
new file mode 100644
index 0000000..ca85a88
--- /dev/null
+++ b/test/testcases/highlighting-span.options
@@ -0,0 +1 @@
+:syntax_highlighter: :coderay
diff --git a/test/testcases/highlighting-span.text b/test/testcases/highlighting-span.text
new file mode 100644
index 0000000..7373290
--- /dev/null
+++ b/test/testcases/highlighting-span.text
@@ -0,0 +1 @@
+You can say `x = Class.new`{:.language-ruby}, for example.
diff --git a/test/testcases/highlighting.html b/test/testcases/highlighting.html
new file mode 100644
index 0000000..5a2ea48
--- /dev/null
+++ b/test/testcases/highlighting.html
@@ -0,0 +1,6 @@
+<div class="language-ruby highlighter-coderay"><span class="CodeRay">x = <span class="constant">Class</span>.new
+</span>
+</div>
+<div class="language-html highlighter-coderay"><span class="CodeRay"><span class="tag">&lt;a&gt;</span>href<span class="tag">&lt;/a&gt;</span>
+</span>
+</div>
diff --git a/test/testcases/highlighting.options b/test/testcases/highlighting.options
new file mode 100644
index 0000000..c8b8162
--- /dev/null
+++ b/test/testcases/highlighting.options
@@ -0,0 +1,6 @@
+:syntax_highlighter: :coderay
+:coderay_default_lang: ruby
+:coderay_wrap: span
+:coderay_line_numbers: ~
+:coderay_css: class
+
diff --git a/test/testcases/highlighting.text b/test/testcases/highlighting.text
new file mode 100644
index 0000000..5ac4746
--- /dev/null
+++ b/test/testcases/highlighting.text
@@ -0,0 +1,4 @@
+    x = Class.new
+^
+    <a>href</a>
+{: .language-html}