diff --git a/examples/config.yml b/examples/config.yml
index 515549c..ace7f8d 100644
--- a/examples/config.yml
+++ b/examples/config.yml
@@ -45,6 +45,9 @@ css_classes: &css_classes
 word_count:
   format: word_count
 
+chapters:
+  format: chapters
+
 summary_plain:
   format: summary_plain
 
diff --git a/examples/full.chapters.json b/examples/full.chapters.json
new file mode 100644
index 0000000..634cbed
--- /dev/null
+++ b/examples/full.chapters.json
@@ -0,0 +1,16 @@
+[
+  {
+    "slug": "chapter-1",
+    "title": "Chapter 1",
+    "chapters": [
+
+    ]
+  },
+  {
+    "slug": "chapter-2",
+    "title": "Chapter 2",
+    "chapters": [
+
+    ]
+  }
+]
diff --git a/examples/full.repub b/examples/full.repub
index 57ac233..81bf7d2 100644
--- a/examples/full.repub
+++ b/examples/full.repub
@@ -33,7 +33,7 @@ end
 
 
 
-article.chapter 'Chapter 1' do |chapter|
+article.chapter 'chapter-1', 'Chapter 1' do |chapter|
   chapter.paragraph do |paragraph|
     paragraph.text 'Chapter 1 paragraph text'
   end
@@ -41,7 +41,7 @@ end
 
 
 
-article.chapter 'Chapter 2' do |chapter|
+article.chapter 'chapter-2', 'Chapter 2' do |chapter|
   chapter.paragraph do |paragraph|
     paragraph.text 'Chapter 2 paragraph text'
   end
diff --git a/examples/hello.chapters.json b/examples/hello.chapters.json
new file mode 100644
index 0000000..41b42e6
--- /dev/null
+++ b/examples/hello.chapters.json
@@ -0,0 +1,3 @@
+[
+
+]
diff --git a/exe/repubmark b/exe/repubmark
index fa15677..1d52bab 100755
--- a/exe/repubmark
+++ b/exe/repubmark
@@ -36,10 +36,11 @@ end
 
 output =
   case config.format
-  when :word_count    then $article.word_count
-  when :summary_plain then wrap $article.to_summary_plain
-  when :html          then $article.to_html
+  when :chapters      then JSON.pretty_generate $article.chapters
   when :gemtext       then $article.to_gemtext
+  when :html          then $article.to_html
+  when :summary_plain then wrap $article.to_summary_plain
+  when :word_count    then $article.word_count
   end.to_s.strip
 
 puts output unless output.empty?
diff --git a/lib/repubmark.rb b/lib/repubmark.rb
index 5ea22d5..8f79d5b 100644
--- a/lib/repubmark.rb
+++ b/lib/repubmark.rb
@@ -64,7 +64,7 @@ require_relative 'repubmark/elems/power'
 require_relative 'repubmark/elems/footnote'
 
 module Repubmark
-  FORMATS = %i[gemtext html summary_plain word_count].freeze
+  FORMATS = %i[chapters gemtext html summary_plain word_count].freeze
 
   SLUG_RE = /\A\w+(-\w+)*\z/
 
diff --git a/lib/repubmark/elems/article.rb b/lib/repubmark/elems/article.rb
index 8041dce..bec8aa3 100644
--- a/lib/repubmark/elems/article.rb
+++ b/lib/repubmark/elems/article.rb
@@ -45,6 +45,8 @@ module Repubmark
         ].compact.join("\n\n\n").freeze
       end
 
+      def chapters = @chapter&.chapters[:chapters] || [].freeze
+
       ###################
       # Builder methods #
       ###################
diff --git a/lib/repubmark/elems/chapter.rb b/lib/repubmark/elems/chapter.rb
index ac9e6a6..308a5eb 100644
--- a/lib/repubmark/elems/chapter.rb
+++ b/lib/repubmark/elems/chapter.rb
@@ -5,9 +5,10 @@ module Repubmark
     class Chapter < Base
       parents :Article, :Chapter
 
-      def initialize(parent, level = 1, title = nil)
+      def initialize(parent, level = 1, slug = nil, title = nil)
         super parent
         self.level = level
+        self.slug = slug
         self.title = title
         verify!
 
@@ -51,12 +52,20 @@ module Repubmark
         ].join.freeze
       end
 
+      def chapters
+        {
+          slug: @slug,
+          title: @title,
+          chapters: @chapters.map(&:chapters).freeze,
+        }.freeze
+      end
+
       ###################
       # Builder methods #
       ###################
 
-      def chapter(title)
-        chapter = Chapter.new self, @level + 1, title
+      def chapter(slug, title)
+        chapter = Chapter.new self, @level + 1, slug, title
         @chapters << chapter
         yield chapter
         nil
@@ -85,6 +94,10 @@ module Repubmark
         @level = level
       end
 
+      def slug=(slug)
+        @slug = Repubmark.validate_slug! slug if slug
+      end
+
       def title=(title)
         return @title = nil if title.nil?
 
@@ -95,8 +108,13 @@ module Repubmark
       end
 
       def verify!
-        raise 'Non-empty title for level 1' if @level == 1 && @title
-        raise 'Empty title for level >= 2'  if @level != 1 && @title.nil?
+        if @level == 1
+          raise 'Non-empty slug for level 1'  if @slug
+          raise 'Non-empty title for level 1' if @title
+        else
+          raise 'Empty slug for level >= 2'   if @slug.nil?
+          raise 'Empty title for level >= 2'  if @title.nil?
+        end
       end
 
       def build_title_html
diff --git a/test.rb b/test.rb
index 14eaf43..d93278a 100755
--- a/test.rb
+++ b/test.rb
@@ -12,6 +12,7 @@ PROFILES = [
   %w[summary_plain summary.txt],
   %w[http html],
   %w[gemini gmi],
+  %w[chapters chapters.json],
 ].map(&:freeze).freeze
 
 Dir[EXAMPLES_GLOB].each do |example_filename|