diff --git a/.gitignore b/.gitignore
index 1adbebc..4834e46 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,44 @@
+*.gem
+*.rbc
+*.so
+
+/.byebug_history
+/.config/
+/.rake_tasks~
+/InstalledFiles/
+/pkg/
+/tmp/
+
+# Used by dotenv library to load environment variables.
+/.env
+
+# RSpec configuration and generated files.
+/.rspec
+/coverage/
+/spec/examples.txt
+/spec/reports/
+/test/tmp/
+/test/version_tmp/
+
+# Documentation cache and generated files.
+/.yardoc/
+/_yardoc/
+/doc/
+/rdoc/
+
+# Environment normalization.
+/.bundle/
+/vendor/bundle/
+/lib/bundler/man/
+
+# For a library or gem, you might want to ignore these files since the code is
+# intended to run in multiple environments; otherwise, check them in.
 /Gemfile.lock
 /.ruby-version
 /.ruby-gemset
+
+# Unless supporting rvm < 1.11.0 or doing something fancy, ignore this.
+/.rvmrc
+
+# Used by RuboCop. Remote config files pulled in from inherit_from directive.
+/.rubocop-https?--*
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..f34db8d
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,46 @@
+inherit_from: .rubocop_todo.yml
+
+require:
+  - rubocop-performance
+  - rubocop-rake
+
+AllCops:
+  TargetRubyVersion: 3.2
+  DisplayCopNames: true
+  NewCops: enable
+
+Layout/AccessModifierIndentation:
+  EnforcedStyle: outdent
+
+Layout/LineLength:
+  Max: 80
+
+Lint/AmbiguousOperatorPrecedence:
+  Enabled: false
+
+Lint/ReturnInVoidContext:
+  Enabled: false
+
+Style/AndOr:
+  EnforcedStyle: conditionals
+
+Style/DoubleNegation:
+  Enabled: false
+
+Style/HashAsLastArrayItem:
+  Enabled: false
+
+Style/PerlBackrefs:
+  Enabled: false
+
+Style/TrailingCommaInArguments:
+  EnforcedStyleForMultiline: comma
+
+Style/TrailingCommaInArrayLiteral:
+  EnforcedStyleForMultiline: comma
+
+Style/TrailingCommaInHashLiteral:
+  EnforcedStyleForMultiline: comma
+
+Style/VariableInterpolation:
+  Enabled: false
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
new file mode 100644
index 0000000..47477d5
--- /dev/null
+++ b/.rubocop_todo.yml
@@ -0,0 +1,129 @@
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2024-10-18 14:41:13 UTC using RuboCop version 1.67.0.
+# The point is for the user to remove these configuration records
+# one by one as the offenses are removed from the code base.
+# Note that changes in the inspected code, or installation of new
+# versions of RuboCop, may require this file to be generated again.
+
+# Offense count: 2
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: EnforcedStyle, IndentationWidth.
+# SupportedStyles: with_first_argument, with_fixed_indentation
+Layout/ArgumentAlignment:
+  Exclude:
+    - 'Rakefile'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: Max, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, AllowedPatterns.
+# URISchemes: http, https
+Layout/LineLength:
+  Exclude:
+    - 'lib/repubmark/elems/footnote.rb'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowedMethods.
+# AllowedMethods: present?, blank?, presence, try, try!, in?
+Lint/SafeNavigationChain:
+  Exclude:
+    - 'lib/repubmark/elems/article.rb'
+
+# Offense count: 1
+# Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes.
+Metrics/AbcSize:
+  Max: 35
+
+# Offense count: 1
+# Configuration parameters: CountComments, CountAsOne.
+Metrics/ClassLength:
+  Max: 104
+
+# Offense count: 1
+# Configuration parameters: AllowedMethods, AllowedPatterns.
+Metrics/CyclomaticComplexity:
+  Max: 10
+
+# Offense count: 5
+# Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
+Metrics/MethodLength:
+  Max: 33
+
+# Offense count: 1
+# Configuration parameters: AllowedMethods, AllowedPatterns.
+Metrics/PerceivedComplexity:
+  Max: 11
+
+# Offense count: 2
+Performance/MapMethodChain:
+  Exclude:
+    - 'lib/repubmark/elems/footnotes_category.rb'
+
+# Offense count: 14
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowOnlyRestArgument, UseAnonymousForwarding, RedundantRestArgumentNames, RedundantKeywordRestArgumentNames, RedundantBlockArgumentNames.
+# RedundantRestArgumentNames: args, arguments
+# RedundantKeywordRestArgumentNames: kwargs, options, opts
+# RedundantBlockArgumentNames: blk, block, proc
+Style/ArgumentsForwarding:
+  Exclude:
+    - 'lib/repubmark/elems/canvas.rb'
+    - 'lib/repubmark/elems/footnotes_category.rb'
+    - 'lib/repubmark/elems/joint.rb'
+    - 'lib/repubmark/elems/link.rb'
+
+# Offense count: 34
+# Configuration parameters: AllowedConstants.
+Style/Documentation:
+  Enabled: false
+
+# Offense count: 7
+# Configuration parameters: AllowedVariables.
+Style/GlobalVars:
+  Exclude:
+    - 'exe/repubmark'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowIfModifier.
+Style/IfInsideElse:
+  Exclude:
+    - 'lib/repubmark/elems/footnote.rb'
+
+# Offense count: 4
+# This cop supports safe autocorrection (--autocorrect).
+Style/RedundantFreeze:
+  Exclude:
+    - 'lib/repubmark/elems/fraction.rb'
+    - 'lib/repubmark/elems/power.rb'
+
+# Offense count: 2
+# This cop supports safe autocorrection (--autocorrect).
+Style/RedundantStringEscape:
+  Exclude:
+    - 'lib/repubmark/elems/footnote.rb'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowModifier.
+Style/SoleNestedConditional:
+  Exclude:
+    - 'lib/repubmark/elems/footnote.rb'
+
+# Offense count: 7
+# This cop supports safe autocorrection (--autocorrect).
+Style/SuperArguments:
+  Exclude:
+    - 'lib/repubmark/elems/annotation.rb'
+    - 'lib/repubmark/elems/blockquote.rb'
+    - 'lib/repubmark/elems/canvas.rb'
+    - 'lib/repubmark/elems/caption.rb'
+    - 'lib/repubmark/elems/figures.rb'
+    - 'lib/repubmark/elems/joint.rb'
+    - 'lib/repubmark/elems/paragraph.rb'
+
+# Offense count: 24
+# This cop supports safe autocorrection (--autocorrect).
+Style/SuperWithArgsParentheses:
+  Enabled: false
diff --git a/.yardopts b/.yardopts
new file mode 100644
index 0000000..505c853
--- /dev/null
+++ b/.yardopts
@@ -0,0 +1,4 @@
+--markup markdown
+--readme README.md
+--protected
+--private
diff --git a/Gemfile b/Gemfile
index 46eb342..d3b131c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,5 +2,15 @@
 
 source 'https://rubygems.org'
 
-gem 'addressable', '~> 2.8'
-gem 'i18n', '~> 1.14'
+# Specify your gem's dependencies in repubmark.gemspec
+gemspec
+
+group :development do
+  gem 'bundler',             '~> 2.4'
+  gem 'pry',                 '~> 0.14'
+  gem 'rake',                '~> 13.2'
+  gem 'rubocop',             '~> 1.67'
+  gem 'rubocop-performance', '~> 1.22'
+  gem 'rubocop-rake',        '~> 0.6.0'
+  gem 'yard',                '~> 0.9.37'
+end
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..43c2505
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+
+require 'bundler/gem_tasks'
+
+module Bundler
+  class GemHelper
+    def tag_version(*)
+      yield if block_given?
+    end
+
+    def git_push(*); end
+
+    def perform_git_push(*); end
+  end
+end
+
+CLEAN << '.yardoc'
+CLEAN << 'coverage'
+CLEAN << 'doc'
+
+desc 'Run default checks'
+task default: %i[test lint]
+
+desc 'Run tests'
+task test: :tests
+
+desc 'Run code analysis tools'
+task lint: %i[rubocop yard:cov]
+
+desc 'Fix code style (rubocop --auto-correct)'
+task fix: 'rubocop:auto_correct'
+
+begin
+  require 'rubocop/rake_task'
+  RuboCop::RakeTask.new
+rescue LoadError
+  nil
+end
+
+begin
+  require 'yard'
+  YARD::Rake::YardocTask.new
+rescue LoadError
+  nil
+end
+
+desc 'Open development console'
+task :console do
+  sh 'bundle', 'exec',
+    File.expand_path(File.join('bin', 'console'), __dir__)
+end
+
+desc 'Run tests'
+task :tests do
+  sh 'bundle', 'exec',
+    File.expand_path(File.join('tests', 'examples.rb'), __dir__)
+end
+
+namespace :yard do
+  desc 'Measure documentation coverage'
+  task :cov do
+    result = `bundle exec yard stats`.lines.last.strip.freeze
+    m = result.match(/\A(\d+(\.\d+)?)% documented\z/)
+    raise 'Invalid result' if m.nil?
+
+    coverage = m[1].to_f.round(2)
+    puts "Documentation coverage: #{coverage}%"
+    raise 'Not fully documented!' if coverage < 38.32
+  end
+end
diff --git a/bin/console b/bin/console
new file mode 100755
index 0000000..78f97aa
--- /dev/null
+++ b/bin/console
@@ -0,0 +1,9 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'bundler/setup'
+
+require 'pry'
+require 'repubmark'
+
+Pry.start
diff --git a/bin/setup b/bin/setup
new file mode 100755
index 0000000..b804c0a
--- /dev/null
+++ b/bin/setup
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -euvx
+
+bundle install
diff --git a/lib/repubmark.rb b/lib/repubmark.rb
index 0a5f568..b8aebb7 100644
--- a/lib/repubmark.rb
+++ b/lib/repubmark.rb
@@ -63,6 +63,10 @@ require_relative 'repubmark/elems/power'
 # Always inside FootnotesCategory
 require_relative 'repubmark/elems/footnote'
 
+##
+# A Markdown-inspired markup language that can be compiled into HTML and
+# Gemtext.
+#
 module Repubmark
   FORMATS = %i[chapters gemtext html summary_plain word_count].freeze
 
diff --git a/lib/repubmark/version.rb b/lib/repubmark/version.rb
new file mode 100644
index 0000000..f3dfeab
--- /dev/null
+++ b/lib/repubmark/version.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+module Repubmark
+  # Gem version.
+  VERSION = '0.0.0'
+end
diff --git a/repubmark.gemspec b/repubmark.gemspec
new file mode 100644
index 0000000..30e705f
--- /dev/null
+++ b/repubmark.gemspec
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require_relative 'lib/repubmark/version'
+
+Gem::Specification.new do |spec|
+  repo = 'https://git.causa-arcana.com/causa-arcana/repubmark'
+  mail = 'me+repubmark@kotovalexarian.com'
+  home = repo
+  # bugs = "mailto:#{mail}"
+  docs = "https://www.rubydoc.info/gems/repubmark/#{Repubmark::VERSION}"
+
+  spec.name     = 'repubmark'
+  spec.version  = Repubmark::VERSION
+  spec.license  = 'MIT'
+  spec.homepage = home
+
+  spec.required_ruby_version = '~> 3.2'
+
+  spec.authors = ['Alex Kotov']
+  spec.email   = [mail]
+
+  spec.summary =
+    'A Markdown-inspired markup language ' \
+    'that can be compiled into HTML and Gemtext'
+
+  spec.description = <<~DESCRIPTION.split("\n").map(&:strip).join ' '
+    A Markdown-inspired markup language that can be compiled into HTML and
+    Gemtext
+  DESCRIPTION
+
+  spec.metadata['rubygems_mfa_required'] = 'true'
+  spec.metadata['homepage_uri']          = home
+  spec.metadata['source_code_uri']       = home
+  # spec.metadata['bug_tracker_uri']     = FIXME: bugs
+  spec.metadata['documentation_uri']     = docs
+  # spec.metadata['changelog_uri']       = 'TODO: changelog'
+
+  spec.bindir        = 'exe'
+  spec.require_paths = ['lib']
+
+  spec.files = Dir.chdir __dir__ do
+    `git ls-files -z`.split("\x0").reject do |f|
+      (File.expand_path(f) == __FILE__) ||
+        f.start_with?(*%w[.git bin/ test/ spec/ features/ Gemfile])
+    end
+  end
+
+  spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename f }
+
+  spec.add_dependency 'addressable', '~> 2.8'
+  spec.add_dependency 'i18n',        '~> 1.14'
+end