diff --git a/README.md b/README.md
index 7cd897a..2ed496c 100644
--- a/README.md
+++ b/README.md
@@ -297,6 +297,29 @@ end
 puts NamedArgumentsView.new.to_html
 ```
 
+#### `data` / `aria` Helpers
+
+You can define `data-*` and `aria-*` attributes via `data:` / `aria:` hashes or named tuples.
+When multiple sources assign the same `data-*` / `aria-*` key, the last assignment wins.
+
+```crystal
+require "to_html"
+
+class DataAriaView
+  ToHtml.instance_template do
+    div(
+      {"data-foo", "from-tuple"},
+      data_foo: "from-explicit",
+      data: {foo: "from-hash", user_id: 42, active: true, ignored: nil},
+      aria: {label: "Profile", hidden: false}
+    )
+  end
+end
+
+# <div data-foo="from-hash" data-user-id="42" data-active="true" aria-label="Profile" aria-hidden="false"></div>
+puts DataAriaView.new.to_html
+```
+
 #### Object Interface
 
 Another way to add attributes is via objects that implement `#to_html_attrs`. The easiest way to do so is via the `ToHtml.instance_tag_attrs`/`ToHtml.class_tag_attrs` macros.
diff --git a/shard.yml b/shard.yml
index 6951038..89a3494 100644
--- a/shard.yml
+++ b/shard.yml
@@ -1,5 +1,5 @@
 name: to_html
-version: 1.6.0
+version: 1.7.0
 license: MIT
 authors:
   - Stefan Bilharz <stefan@sbsoftware.de>
diff --git a/spec/instance_template/case_spec.cr b/spec/instance_template/case_spec.cr
new file mode 100644
index 0000000..09d2cc3
--- /dev/null
+++ b/spec/instance_template/case_spec.cr
@@ -0,0 +1,83 @@
+require "../spec_helper"
+
+module ToHtml::InstanceTemplate::CaseSpec
+  enum Kind
+    A
+    B
+    Other
+  end
+
+  class MyView
+    getter kind : Kind
+
+    def initialize(@kind)
+    end
+
+    ToHtml.instance_template do
+      case kind
+      when Kind::A
+        p { "A" }
+      when Kind::B
+        div do
+          span { "B" }
+        end
+      else
+        i { "Other" }
+      end
+
+      div do
+        case
+        when kind == Kind::A
+          strong { "inner-a" }
+        else
+          em { "inner-not-a" }
+        end
+      end
+    end
+
+    describe "MyView#to_html" do
+      it "renders the correct HTML for Kind::A" do
+        expected = <<-HTML
+        <p>A</p>
+        <div>
+          <strong>
+            inner-a
+          </strong>
+        </div>
+        HTML
+
+        MyView.new(Kind::A).to_html.should eq(expected.squish)
+      end
+
+      it "renders the correct HTML for Kind::B" do
+        expected = <<-HTML
+        <div>
+          <span>
+            B
+          </span>
+        </div>
+        <div>
+          <em>
+            inner-not-a
+          </em>
+        </div>
+        HTML
+
+        MyView.new(Kind::B).to_html.should eq(expected.squish)
+      end
+
+      it "renders the correct HTML for Kind::Other" do
+        expected = <<-HTML
+        <i>Other</i>
+        <div>
+          <em>
+            inner-not-a
+          </em>
+        </div>
+        HTML
+
+        MyView.new(Kind::Other).to_html.should eq(expected.squish)
+      end
+    end
+  end
+end
diff --git a/spec/instance_template/data_aria_attributes_spec.cr b/spec/instance_template/data_aria_attributes_spec.cr
new file mode 100644
index 0000000..4a2296a
--- /dev/null
+++ b/spec/instance_template/data_aria_attributes_spec.cr
@@ -0,0 +1,74 @@
+require "../spec_helper"
+
+module ToHtml::InstanceTemplate::DataAriaAttributesSpec
+  class BasicView
+    ToHtml.instance_template do
+      div data: {foo: "bar"}, aria: {label: "X"}
+    end
+  end
+
+  class TypeView
+    ToHtml.instance_template do
+      div data: {enabled: true, count: 7, ratio: 2.5, ignored: nil}, aria: {hidden: false, current: nil}
+    end
+  end
+
+  class ProviderAttrs
+    ToHtml.class_tag_attrs do
+      data = {foo: "provider-hash", bar: 1}
+      aria = {label: "provider-label"}
+      data_foo = "provider-explicit"
+      aria_label = "provider-explicit-label"
+    end
+  end
+
+  class MergeView
+    ToHtml.instance_template do
+      attrs = [
+        ProviderAttrs,
+        {data: {foo: "array-hash", baz: true}, aria: {label: "array-label", hidden: false}},
+      ]
+
+      div attrs, {"data-foo", "tuple-explicit"}, {"aria-label", "tuple-explicit-label"},
+        data_foo: "named-explicit",
+        aria_label: "named-explicit-label",
+        data: {"foo" => "named-hash-last", "count" => 2.5, "bar" => nil, "data-prefixed" => "normalized"},
+        aria: {"label" => "named-label-last", "current" => false, "omitted" => nil}
+    end
+  end
+
+  class NormalizeView
+    ToHtml.instance_template do
+      div data: {"foo_bar" => "snake", :"foo-baz" => "dash", :"data-qux" => "prefixed"},
+        aria: {"labelled_by" => "target", :"aria-described-by" => "description"}
+    end
+  end
+
+  class NestedView
+    ToHtml.instance_template do
+      div data: {foo: {blah: "baz"}}, aria: {label: {text: "X"}}
+    end
+  end
+
+  describe "data/aria attribute expansion" do
+    it "expands data and aria named tuple attributes" do
+      BasicView.new.to_html.should eq(%(<div data-foo="bar" aria-label="X"></div>))
+    end
+
+    it "serializes bool and numbers while omitting nil values" do
+      TypeView.new.to_html.should eq(%(<div data-enabled="true" data-count="7" data-ratio="2.5" aria-hidden="false"></div>))
+    end
+
+    it "merges array, tuple, to_html_attrs, and named args with last-write-wins semantics" do
+      MergeView.new.to_html.should eq(%(<div data-foo="named-hash-last" aria-label="named-label-last" data-baz="true" aria-hidden="false" data-count="2.5" data-prefixed="normalized" aria-current="false"></div>))
+    end
+
+    it "normalizes symbol and string keys for data/aria hashes" do
+      NormalizeView.new.to_html.should eq(%(<div data-foo-bar="snake" data-foo-baz="dash" data-qux="prefixed" aria-labelled-by="target" aria-described-by="description"></div>))
+    end
+
+    it "flattens nested data/aria hashes and named tuples" do
+      NestedView.new.to_html.should eq(%(<div data-foo-blah="baz" aria-label-text="X"></div>))
+    end
+  end
+end
diff --git a/spec/instance_template/iterator_blocks_spec.cr b/spec/instance_template/iterator_blocks_spec.cr
new file mode 100644
index 0000000..303e61b
--- /dev/null
+++ b/spec/instance_template/iterator_blocks_spec.cr
@@ -0,0 +1,95 @@
+require "../spec_helper"
+
+module ToHtml::InstanceTemplate::IteratorBlocksSpec
+  class IndexedItem
+    getter value : String
+
+    def initialize(@value)
+    end
+
+    ToHtml.instance_template do
+      em { value }
+    end
+  end
+
+  class IndexedList
+    getter items : Array(String)
+
+    def initialize(@items)
+    end
+
+    ToHtml.instance_template do
+      ul do
+        items.each_with_index do |item, idx|
+          li do
+            if idx.even?
+              span { idx.to_s }
+            else
+              IndexedItem.new(item)
+            end
+
+            unless idx == items.size - 1
+              small { "present" }
+            end
+          end
+        end
+      end
+    end
+  end
+
+  class TimesList
+    ToHtml.instance_template do
+      ol do
+        3.times do |i|
+          li do
+            if i.even?
+              "even"
+            else
+              "odd"
+            end
+          end
+        end
+
+        2.times do
+          li { "tail" }
+        end
+      end
+    end
+  end
+
+  describe "iterator blocks" do
+    it "supports each_with_index with nested template control flow" do
+      expected = <<-HTML
+      <ul>
+        <li>
+          <span>
+            0
+          </span>
+          <small>present</small>
+        </li>
+        <li>
+          <em>
+            two
+          </em>
+        </li>
+      </ul>
+      HTML
+
+      IndexedList.new(["one", "two"]).to_html.should eq(expected.squish)
+    end
+
+    it "supports times with and without block args" do
+      expected = <<-HTML
+      <ol>
+        <li>even</li>
+        <li>odd</li>
+        <li>even</li>
+        <li>tail</li>
+        <li>tail</li>
+      </ol>
+      HTML
+
+      TimesList.new.to_html.should eq(expected.squish)
+    end
+  end
+end
diff --git a/src/attribute_hash.cr b/src/attribute_hash.cr
index 9a1b288..17a01fd 100644
--- a/src/attribute_hash.cr
+++ b/src/attribute_hash.cr
@@ -10,12 +10,30 @@ module ToHtml
     end
 
     def []=(key, value : Bool)
+      key = key.to_s
+
+      if prefixed_key = normalize_explicit_prefixed_key(key)
+        attributes[prefixed_key] = value.to_s
+        return
+      end
+
       return unless value
 
       boolean_attributes << key
     end
 
     def []=(key, value)
+      key = key.to_s
+
+      if prefixed_key = normalize_explicit_prefixed_key(key)
+        assign_prefixed_value(prefixed_key, value)
+        return
+      end
+
+      if key == "data" || key == "aria"
+        return if assign_prefixed_hash(key, value)
+      end
+
       if attributes.has_key?(key)
         attributes[key] += " #{value}" if value
       else
@@ -38,5 +56,57 @@ module ToHtml
       io << " " if boolean_attributes.any?
       boolean_attributes.join(io, " ")
     end
+
+    private def assign_prefixed_hash(prefix : String, value : Hash | NamedTuple) : Bool
+      prefix_with_separator = "#{prefix}-"
+      value.each do |raw_key, raw_value|
+        key = raw_key.to_s.strip.gsub("_", "-")
+        next if key.empty? || key == prefix
+
+        if key.starts_with?(prefix_with_separator)
+          next if key.size == prefix_with_separator.size
+
+          assign_prefixed_value(key, raw_value)
+        else
+          assign_prefixed_value("#{prefix_with_separator}#{key}", raw_value)
+        end
+      end
+
+      true
+    end
+
+    private def assign_prefixed_hash(_prefix : String, _value) : Bool
+      false
+    end
+
+    private def normalize_explicit_prefixed_key(key : String) : String?
+      key = key.gsub("_", "-")
+
+      if key.starts_with?("data-")
+        return if key == "data-"
+        key
+      elsif key.starts_with?("aria-")
+        return if key == "aria-"
+        key
+      end
+    end
+
+    # Nested data/aria maps are flattened recursively into hyphen-separated keys.
+    private def assign_prefixed_value(key : String, value : Hash | NamedTuple)
+      value.each do |raw_key, raw_value|
+        nested_key_part = raw_key.to_s.strip.gsub("_", "-")
+        next if nested_key_part.empty?
+
+        assign_prefixed_value("#{key}-#{nested_key_part}", raw_value)
+      end
+    end
+
+    private def assign_prefixed_value(key : String, _value : Nil)
+      attributes.delete(key)
+    end
+
+    private def assign_prefixed_value(key : String, value)
+      attributes[key] = value.to_s
+    end
   end
 end
diff --git a/src/instance_template.cr b/src/instance_template.cr
index c02dcef..4f05b9b 100644
--- a/src/instance_template.cr
+++ b/src/instance_template.cr
@@ -83,14 +83,44 @@ module ToHtml
       ToHtml.to_html_add_tag({{io}}, {{indent_level}}, {{break_line}}, {{blk.body}})
     {% elsif blk.body.is_a?(Call) && blk.body.receiver.nil? && blk.body.name.stringify == "doctype" %}
       {{io}} << "<!DOCTYPE {{blk.body.args.first.id}}>"
-    {% elsif blk.body.is_a?(Call) && blk.body.receiver && blk.body.name.stringify == "each" %}
-      {{blk.body.receiver}}.each_with_index do {% if !blk.body.block.args.empty? %} |{{blk.body.block.args.splat}}, %index| {% end %}
+    {% elsif blk.body.is_a?(Call) && blk.body.receiver && blk.body.block && blk.body.name.stringify == "each" %}
+      {% if flag?(:to_html_pretty) %}
+        %to_html_each_break_line = false
+      {% end %}
+      {{blk.body.receiver}}.each do {% if !blk.body.block.args.empty? %} |{{blk.body.block.args.splat}}| {% end %}
+        {% if flag?(:to_html_pretty) %}
+          {{io}} << "\n" if %to_html_each_break_line
+          %to_html_each_break_line = true
+        {% end %}
         ToHtml.to_html_eval_exps({{io}}, {{indent_level}}) do
           {{blk.body.block.body}}
         end
+      end
+    {% elsif blk.body.is_a?(Call) && blk.body.receiver && blk.body.block && blk.body.name.stringify == "each_with_index" %}
+      {% if flag?(:to_html_pretty) %}
+        %to_html_each_with_index_break_line = false
+      {% end %}
+      {{blk.body.receiver}}.each_with_index do {% if !blk.body.block.args.empty? %} |{{blk.body.block.args.splat}}| {% end %}
         {% if flag?(:to_html_pretty) %}
-          {{io}} << "\n" unless %index == {{blk.body.receiver}}.size - 1
+          {{io}} << "\n" if %to_html_each_with_index_break_line
+          %to_html_each_with_index_break_line = true
         {% end %}
+        ToHtml.to_html_eval_exps({{io}}, {{indent_level}}) do
+          {{blk.body.block.body}}
+        end
+      end
+    {% elsif blk.body.is_a?(Call) && blk.body.receiver && blk.body.block && blk.body.name.stringify == "times" %}
+      {% if flag?(:to_html_pretty) %}
+        %to_html_times_break_line = false
+      {% end %}
+      {{blk.body.receiver}}.times do {% if !blk.body.block.args.empty? %} |{{blk.body.block.args.splat}}| {% end %}
+        {% if flag?(:to_html_pretty) %}
+          {{io}} << "\n" if %to_html_times_break_line
+          %to_html_times_break_line = true
+        {% end %}
+        ToHtml.to_html_eval_exps({{io}}, {{indent_level}}) do
+          {{blk.body.block.body}}
+        end
       end
     {% elsif blk.body.is_a?(Call) && blk.body.receiver && blk.body.name.stringify == "to_html" && blk.body.block %}
       {{blk.body.receiver}}.to_html({{io}}, {{indent_level}}) do |%io, %indent_level|
@@ -130,6 +160,27 @@ module ToHtml
           {% end %}
       {% end %}
       end
+    {% elsif blk.body.is_a?(Case) %}
+      case {{blk.body.cond}}
+      {% for w in blk.body.whens %}
+        when {{w.conds.splat}}
+          ToHtml.to_html_eval_exps({{io}}, {{indent_level}}) do
+            {{w.body}}
+          end
+          {% if flag?(:to_html_pretty) && break_line %}
+            {{io}} << "\n"
+          {% end %}
+      {% end %}
+      {% if !blk.body.else.is_a?(Nop) %}
+        else
+          ToHtml.to_html_eval_exps({{io}}, {{indent_level}}) do
+            {{blk.body.else}}
+          end
+          {% if flag?(:to_html_pretty) && break_line %}
+            {{io}} << "\n"
+          {% end %}
+      {% end %}
+      end
     {% elsif blk.body.is_a?(MacroIf) %}
       \{% if {{blk.body.cond}} %}
         ToHtml.to_html_eval_exps({{io}}, {{indent_level}}) do
@@ -251,7 +302,7 @@ module ToHtml
           %attr_hash[{{arg}}.first] = {{arg}}.last
         {% else %}
           %arg = {{arg}}
-          if %arg.is_a?(Array)
+          if %arg.is_a?(Array) || %arg.is_a?(Tuple)
             %arg.each do |item|
               item.to_html_attrs({{call.name.stringify}}, %attr_hash)
             end