diff --git a/extra/html-extra/HtmlAttributes.php b/extra/html-extra/HtmlAttributes.php
new file mode 100644
index 0000000000..5ad7b40360
--- /dev/null
+++ b/extra/html-extra/HtmlAttributes.php
@@ -0,0 +1,162 @@
+<?php
+
+namespace Twig\Extra\Html;
+
+use Twig\Error\RuntimeError;
+
+final class HtmlAttributes
+{
+    /**
+     * Merges multiple attribute group arrays into a single array.
+     *
+     * `HtmlAttributes::merge(['id' => 'a', 'disabled' => true], ['hidden' => true])` becomes
+     * `['id' => 'a', 'disabled' => true, 'hidden' => true]`
+     *
+     * attributes override each other in the order they are provided.
+     *
+     * `HtmlAttributes::merge(['id' => 'a'], ['id' => 'b'])` becomes `['id' => 'b']`.
+     *
+     * However, `class` and `style` attributes are merged into an array so they can be concatenated in later processing.
+     *
+     * `HtmlAttributes::merge(['class' => 'a'], ['class' => 'b'], ['class' => 'c'])` becomes
+     * `['class' => ['a' => true, 'b' => true, 'c' => true]]`.
+     *
+     * style attributes are also merged into an array so they can be concatenated in later processing.
+     * style attributes are split into key, value pairs.
+     *
+     * `HtmlAttributes::merge(['style' => 'color: red'], ['style' => 'background-color: blue'])` becomes
+     * `['style' => ['color' => 'red', 'background-color' => 'blue']]`.
+     *
+     * style attributes which are arrays with false and null values are also processed
+     *
+     * `HtmlAttributes::merge(['style' => ['color: red' => true]], ['style' => ['display: block' => false]]) becomes
+     * `['style' => ['color' => 'red', 'display' => false]]`.
+     *
+     * attributes can be provided as an array of key, value where the value can be true, false or null.
+     *
+     * Example:
+     * `HtmlAttributes::merge(['class' => ['a' => true, 'b' => false], ['class' => ['c' => null']])` becomes
+     * `['class' => ['a' => true, 'b' => false, 'c' => null]]`.
+     *
+     * `aria` and `data` arrays are expanded into `aria-*` and `data-*` attributes before further processing.
+     *
+     * Example:
+     *
+     * `HtmlAttributes::merge([data' => ['count' => '1']])` becomes `['data-count' => '1']`.
+     * `HtmlAttributes::merge(['aria' => ['hidden' => true]])` becomes `['aria-hidden' => true]`.
+     *
+     * @see ./Tests/HtmlAttributesTest.php for usage examples
+     *
+     * @param ...$attributeGroup
+     * @return array
+     * @throws RuntimeError
+     */
+    public static function merge(...$attributeGroup): array
+    {
+        $result = [];
+
+        $attributeGroupCount = 0;
+
+        foreach ($attributeGroup as $attributes) {
+
+            $attributeGroupCount++;
+
+            // Skip empty attributes
+            // Return early if no attributes are provided
+            // This could be false or null when using the twig ternary operator
+            if(!$attributes) {
+                continue;
+            }
+
+            if (!is_iterable($attributes)) {
+                throw new RuntimeError(sprintf('"%s" only works with mappings or "Traversable", got "%s" for argument %d.', self::class, \gettype($attributes), $attributeGroupCount));
+            }
+
+            // Alternative to is_iterable check above, cast the attributes to an array
+            // This would produce weird results but would not throw an error
+//            $attributes = (array)$attributes;
+
+            // data and aria arrays are expanded into data-* and aria-* attributes
+            $expanded = [];
+            foreach ($attributes as $key => $value) {
+                if (in_array($key, ['data', 'aria'])) {
+                    $value = (array)$value;
+                    foreach ($value as $k => $v) {
+                        $k = $key . '-' . $k;
+                        $expanded[$k] = $v;
+                    }
+                    continue;
+                }
+                $expanded[$key] = $value;
+            }
+
+            // Reset the attributes array to the flattened version
+            $attributes = $expanded;
+
+            foreach ($attributes as $key => $value) {
+
+                // Treat class and data-controller attributes as arrays
+                if (in_array($key, [
+                    'class',
+                    'data-controller',
+                    'data-action',
+                    'data-targets',
+                ])) {
+                    if (!array_key_exists($key, $result)) {
+                        $result[$key] = [];
+                    }
+                    $value = (array)$value;
+                    foreach ($value as $k => $v) {
+                        if (is_int($k)) {
+                            $classes = explode(' ', $v);
+                            foreach ($classes as $class) {
+                                $result[$key][$class] = true;
+                            }
+                        } else {
+                            $classes = explode(' ', $k);
+                            foreach ($classes as $class) {
+                                $result[$key][$class] = $v;
+                            }
+                        }
+                    }
+                    continue;
+                }
+
+                if ($key === 'style') {
+                    if (!array_key_exists('style', $result)) {
+                        $result['style'] = [];
+                    }
+                    $value = (array)$value;
+                    foreach ($value as $k => $v) {
+                        if (is_int($k)) {
+                            $styles = array_filter(explode(';', $v));
+                            foreach ($styles as $style) {
+                                $style = explode(':', $style);
+                                $sKey = trim($style[0]);
+                                $sValue = trim($style[1]);
+                                $result['style'][$sKey] = $sValue;
+                            }
+                        } elseif (is_bool($v) || is_null($v)) {
+                            $styles = array_filter(explode(';', $k));
+                            foreach ($styles as $style) {
+                                $style = explode(':', $style);
+                                $sKey = trim($style[0]);
+                                $sValue = trim($style[1]);
+                                $result['style'][$sKey] = $v ? $sValue : $v;
+                            }
+                        } else {
+                            $sKey = trim($k);
+                            $sValue = trim($v);
+                            $result['style'][$sKey] = $sValue;
+                        }
+                    }
+                    continue;
+                }
+
+                $result[$key] = $value;
+            }
+        }
+
+        return $result;
+    }
+}
\ No newline at end of file
diff --git a/extra/html-extra/Tests/HtmlAttributesTest.php b/extra/html-extra/Tests/HtmlAttributesTest.php
new file mode 100644
index 0000000000..6dfe46d78a
--- /dev/null
+++ b/extra/html-extra/Tests/HtmlAttributesTest.php
@@ -0,0 +1,230 @@
+<?php
+
+namespace Twig\Extra\Html\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Twig\Error\RuntimeError;
+use Twig\Extra\Html\HtmlAttributes;
+
+class HtmlAttributesTest extends TestCase
+{
+    /**
+     * @dataProvider htmlAttrProvider
+     * @throws RuntimeError
+     */
+    public function testMerge(array $input, array $expected)
+    {
+        $result = HtmlAttributes::merge(...$input);
+        self::assertSame($expected, $result);
+    }
+
+    public function testNonIterableAttributeValuesThrowException()
+    {
+        $this->expectException(\Twig\Error\RuntimeError::class);
+        $result = HtmlAttributes::merge(['class' => 'a'], 'b');
+    }
+
+    /**
+     * Tests output of HtmlAttributes::merge() method can be used as an array of attributes.
+     * @return void
+     * @throws RuntimeError
+     */
+    public function testMultipleMerge()
+    {
+        $result1 = HtmlAttributes::merge(['a' => 'b', 'c' => 'd'],
+            true ? ['e' => 'f'] : null,
+            false ? ['g' => 'h'] : null,
+            ['i' => true],
+            ['j' => true],
+            ['j' => false],
+            ['k' => true],
+            ['k' => null]
+        );
+
+        $result2 = HtmlAttributes::merge(
+            ['class' => 'a b j'],
+            ['class' => ['c', 'd', 'e f']],
+            ['class' => ['g' => true, 'h' => false, 'i' => true]],
+            ['class' => ['h' => true]],
+            ['class' => ['i' => false]],
+            ['class' => ['j' => null]],
+        );
+
+        $result = HtmlAttributes::merge($result1, $result2);
+
+        self::assertSame([
+            'a' => 'b',
+            'c' => 'd',
+            'e' => 'f',
+            'i' => true,
+            'j' => false,
+            'k' => null,
+            'class' => [
+                'a' => true,
+                'b' => true,
+                'j' => null,
+                'c' => true,
+                'd' => true,
+                'e' => true,
+                'f' => true,
+                'g' => true,
+                'h' => true,
+                'i' => false,
+            ]
+        ], $result);
+    }
+
+
+    public function htmlAttrProvider(): \Generator
+    {
+        yield 'merging basic attributes' => [
+            [
+                ['a' => 'b', 'c' => 'd'],
+                true ? ['e' => 'f'] : null,
+                false ? ['g' => 'h'] : null,
+                ['i' => true],
+                ['j' => true],
+                ['j' => false],
+                ['k' => true],
+                ['k' => null],
+            ],
+            [
+                'a' => 'b',
+                'c' => 'd',
+                'e' => 'f',
+                'i' => true,
+                'j' => false,
+                'k' => null
+            ],
+        ];
+
+        /**
+         * class attributes are merged into an array so they can be concatenated in later processing.
+         */
+        yield 'merging class attributes' => [
+            [
+                ['class' => 'a b j'],
+                ['class' => ['c', 'd', 'e f']],
+                ['class' => ['g' => true, 'h' => false, 'i' => true]],
+                ['class' => ['h' => true]],
+                ['class' => ['i' => false]],
+                ['class' => ['j' => null]],
+            ],
+            ['class' => [
+                'a' => true,
+                'b' => true,
+                'j' => null,
+                'c' => true,
+                'd' => true,
+                'e' => true,
+                'f' => true,
+                'g' => true,
+                'h' => true,
+                'i' => false,
+            ]],
+        ];
+
+        /**
+         * style attributes are merged into an array so they can be concatenated in later processing.
+         * style strings are split into key, value pairs eg. 'color: red' becomes ['color' => 'red']
+         * style attributes which are arrays with false and null values are also processed
+         * false and null values override string values eg. ['display: block' => false] becomes ['display' => false]
+         */
+        yield 'merging style attributes' => [
+            [
+                ['style' => 'a: b;'],
+                ['style' => ['c' => 'd', 'e' => 'f']],
+                ['style' => ['g: h;']],
+                ['style' => [
+                    'i: j; k: l' => true,
+                    'm: n' => false,
+                    'o: p' => null
+                ]],
+            ],
+            ['style' => [
+                'a' => 'b',
+                'c' => 'd',
+                'e' => 'f',
+                'g' => 'h',
+                'i' => 'j',
+                'k' => 'l',
+                'm' => false,
+                'o' => null,
+            ]],
+        ];
+
+        /**
+         * `data` arrays are expanded into `data-*` attributes before further processing.
+         */
+        yield 'merging data-* attributes' => [
+            [
+                ['data-a' => 'a'],
+                ['data-b' => 'b'],
+                ['data-c' => true],
+                ['data-d' => false],
+                ['data-e' => null],
+                ['data-f' => ['a' => 'b']],
+                ['data' => ['g' => 'g', 'h' => true]],
+                ['data-h' => false],
+                ['data-h' => 'h'],
+            ],
+            [
+                'data-a' => 'a',
+                'data-b' => 'b',
+                'data-c' => true,
+                'data-d' => false,
+                'data-e' => null,
+                'data-f' => ['a' => 'b'],
+                'data-g' => 'g',
+                'data-h' => 'h',
+            ],
+        ];
+
+        /**
+         * `aria` arrays are expanded into `aria-*` attributes before further processing.
+         */
+        yield 'merging aria-* attributes' => [
+            [
+                ['aria-a' => 'a'],
+                ['aria-b' => 'b'],
+                ['aria-c' => true],
+                ['aria-d' => false],
+                ['aria-e' => null],
+                ['aria-f' => ['a' => 'b']],
+                ['aria' => ['g' => 'g', 'h' => true]],
+                ['aria-h' => false],
+                ['aria-h' => 'h'],
+            ],
+            [
+                'aria-a' => 'a',
+                'aria-b' => 'b',
+                'aria-c' => true,
+                'aria-d' => false,
+                'aria-e' => null,
+                'aria-f' => ['a' => 'b'],
+                'aria-g' => 'g',
+                'aria-h' => 'h',
+            ],
+        ];
+
+        yield 'merging data-controller attributes' => [
+            [
+                ['data' => ['controller' => 'c1 c2']],
+                ['data-controller' => 'c3'],
+                ['data-controller' => ['c4' => true]],
+                ['data-controller' => ['c5' => false]],
+            ],
+            [
+                'data-controller' => [
+                    'c1' => true,
+                    'c2' => true,
+                    'c3' => true,
+                    'c4' => true,
+                    'c5' => false
+                ],
+            ],
+        ];
+
+
+    }
+}