diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index d0ae48d..41e9ce7 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -32,7 +32,7 @@ jobs:
         uses: ramsey/composer-install@v2
 
       - name: Run tests with coverage results
-        run: vendor/bin/phpunit --coverage-clover ./tests/output/clover.xml
+        run: vendor/bin/phpunit --coverage-clover ./tests/_output/clover.xml
 
       - name: Upload coverage results to Coveralls
         env:
@@ -41,7 +41,7 @@ jobs:
           COVERALLS_FLAG_NAME: ${{ matrix.php }}
         run: |
           composer require php-coveralls/php-coveralls -n
-          vendor/bin/php-coveralls --coverage_clover=./tests/output/clover.xml -v --json_path=./tests/output/coveralls-upload.json
+          vendor/bin/php-coveralls --coverage_clover=./tests/_output/clover.xml -v --json_path=./tests/_output/coveralls-upload.json
   finish:
     name: Close parallel build
     needs: tests
diff --git a/.gitignore b/.gitignore
index dae6bed..86acf06 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,5 +2,5 @@
 vendor
 docker/.env
 .phpunit.result.cache
-/tests/output
-!/tests/output/.gitkeep
\ No newline at end of file
+/tests/_output
+!/tests/_output/.gitkeep
\ No newline at end of file
diff --git a/README.md b/README.md
index 0e68913..1c7f5f1 100644
--- a/README.md
+++ b/README.md
@@ -254,6 +254,36 @@ $color = $nestedDto->getColor(); // ColorEnum::Red
 $colorValue = $colorEnum->value; // 'red'
 ```
 
+#### Return DTO as array
+
+```php
+<?php
+
+declare(strict_types=1);
+
+use Dto\Dto;
+
+/**
+ * @method int getActualNumber()
+ * @method string getProviderName()
+ */
+class SnakeCaseDto extends Dto
+{
+    protected int $actualNumber;
+    protected string $providerName;
+}
+
+$data = [
+    'actualNumber' => 5,
+    'providerName' => 'Main Provider',
+];
+
+$dto = new SnakeCaseDto($data);
+
+$array = $dto->toArray(); // ['actualNumber' => 5, 'providerName' => 'Main Provider']
+$arrayWithSnakeCaseKeys = $dto->toArray(rawKeys: false); // ['actual_number' => 5, 'provider_name' => 'Main Provider']
+```
+
 ## For developers
 
 ### Requirements
@@ -340,4 +370,5 @@ The [php-dto](https://github.com/PetrenkoAnton/php-dto/) library is open-sourced
 
 ## Related projects
 
+- [PetrenkoAnton/key-normalizer](https://github.com/PetrenkoAnton/key-normalizer)
 - [PetrenkoAnton/php-collection](https://github.com/PetrenkoAnton/php-collection)
\ No newline at end of file
diff --git a/VERSION b/VERSION
index 8428158..867e524 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.1.2
\ No newline at end of file
+1.2.0
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 159df90..257befd 100644
--- a/composer.json
+++ b/composer.json
@@ -15,7 +15,8 @@
   ],
   "require": {
     "php": "^8.1",
-    "petrenkoanton/php-collection": "^1.0"
+    "petrenkoanton/php-collection": "^1.0",
+    "petrenkoanton/key-normalizer": "^2.0"
   },
   "require-dev": {
     "phpunit/phpunit": "^9.0",
diff --git a/composer.lock b/composer.lock
index 1522c29..a058bf8 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,8 +4,63 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "5abe8febbc82f02ad890accd90b78452",
+    "content-hash": "d70aa36a4d41dae6fc219b00760e843e",
     "packages": [
+        {
+            "name": "petrenkoanton/key-normalizer",
+            "version": "v2.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/PetrenkoAnton/key-normalizer.git",
+                "reference": "ed0442d85c04501689d4a113b0775574b6684374"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/PetrenkoAnton/key-normalizer/zipball/ed0442d85c04501689d4a113b0775574b6684374",
+                "reference": "ed0442d85c04501689d4a113b0775574b6684374",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.4|^8.0"
+            },
+            "require-dev": {
+                "php-coveralls/php-coveralls": "^2.7",
+                "phpunit/phpunit": "^9.0",
+                "psalm/plugin-phpunit": "^0.18.4",
+                "ramsey/coding-standard": "^2.1",
+                "squizlabs/php_codesniffer": "^3.8",
+                "vimeo/psalm": "^5.16"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "KeyNormalizer\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Anton Petrenko",
+                    "email": "antptrnk@gmail.com",
+                    "homepage": "https://github.com/petrenkoanton",
+                    "role": "Developer"
+                }
+            ],
+            "description": "Converts snake_case to camelCase and vice versa",
+            "keywords": [
+                "camel case",
+                "helper",
+                "snake case"
+            ],
+            "support": {
+                "issues": "https://github.com/PetrenkoAnton/key-normalizer/issues",
+                "source": "https://github.com/PetrenkoAnton/key-normalizer/tree/v2.0.0"
+            },
+            "time": "2024-02-20T14:29:47+00:00"
+        },
         {
             "name": "petrenkoanton/php-collection",
             "version": "v1.1.2",
diff --git a/docker/.env.example b/docker/.env.example
index 5cb6c59..794b3d9 100644
--- a/docker/.env.example
+++ b/docker/.env.example
@@ -1 +1,6 @@
-CONTAINER_NAME=php-dto
\ No newline at end of file
+CONTAINER_NAME=php-dto
+XDEBUG_SESSION=PHPSTORM
+XDEBUG_IDE_KEY=PHPSTORM
+XDEBUG_SERVER_NAME=localhost
+XDEBUG_CLIENT_HOST=host.docker.internal
+XDEBUG_START_WITH_REQUEST=trigger # yes | no | trigger
\ No newline at end of file
diff --git a/docker/docker-compose-php81.yml b/docker/docker-compose-php81.yml
index 01b54f0..aa396c0 100644
--- a/docker/docker-compose-php81.yml
+++ b/docker/docker-compose-php81.yml
@@ -6,13 +6,15 @@ services:
     restart: unless-stopped
     working_dir: /var/www/
     environment:
-      - XDEBUG_SESSION=PHPSTORM
-      - PHP_IDE_CONFIG=serverName=localhost
+      XDEBUG_SESSION: ${XDEBUG_SESSION}
+      PHP_IDE_CONFIG: serverName=${XDEBUG_SERVER_NAME}
+      XDEBUG_CONFIG: "ide_key=${XDEBUG_IDE_KEY} client_host=${XDEBUG_CLIENT_HOST} start_with_request=${XDEBUG_START_WITH_REQUEST}"
     volumes:
       - ./../:/var/www
       - ./ini/xdebug.ini:/usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini
       - ./ini/php-opcache.ini:/usr/local/etc/php/conf.d/opcache.ini
       - ./ini/error_reporting.ini:/usr/local/etc/php/conf.d/error_reporting.ini
+      - ./../tests/_output:/opt/phpstorm-coverage/
     networks:
       - default
 
diff --git a/docker/docker-compose-php82.yml b/docker/docker-compose-php82.yml
index 831de33..1f580f3 100644
--- a/docker/docker-compose-php82.yml
+++ b/docker/docker-compose-php82.yml
@@ -6,13 +6,15 @@ services:
     restart: unless-stopped
     working_dir: /var/www/
     environment:
-      - XDEBUG_SESSION=PHPSTORM
-      - PHP_IDE_CONFIG=serverName=localhost
+      XDEBUG_SESSION: ${XDEBUG_SESSION}
+      PHP_IDE_CONFIG: serverName=${XDEBUG_SERVER_NAME}
+      XDEBUG_CONFIG: "ide_key=${XDEBUG_IDE_KEY} client_host=${XDEBUG_CLIENT_HOST} start_with_request=${XDEBUG_START_WITH_REQUEST}"
     volumes:
       - ./../:/var/www
       - ./ini/xdebug.ini:/usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini
       - ./ini/opcache.ini:/usr/local/etc/php/conf.d/docker-php-ext-opcache.ini
       - ./ini/error_reporting.ini:/usr/local/etc/php/conf.d/error_reporting.ini
+      - ./../tests/_output:/opt/phpstorm-coverage/
     networks:
       - default
 
diff --git a/docker/docker-compose-php83.yml b/docker/docker-compose-php83.yml
index 2d35744..3a138b1 100644
--- a/docker/docker-compose-php83.yml
+++ b/docker/docker-compose-php83.yml
@@ -6,13 +6,15 @@ services:
     restart: unless-stopped
     working_dir: /var/www/
     environment:
-      - XDEBUG_SESSION=PHPSTORM
-      - PHP_IDE_CONFIG=serverName=localhost
+      XDEBUG_SESSION: ${XDEBUG_SESSION}
+      PHP_IDE_CONFIG: serverName=${XDEBUG_SERVER_NAME}
+      XDEBUG_CONFIG: "ide_key=${XDEBUG_IDE_KEY} client_host=${XDEBUG_CLIENT_HOST} start_with_request=${XDEBUG_START_WITH_REQUEST}"
     volumes:
       - ./../:/var/www
       - ./ini/xdebug.ini:/usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini
       - ./ini/opcache.ini:/usr/local/etc/php/conf.d/docker-php-ext-opcache.ini
       - ./ini/error_reporting.ini:/usr/local/etc/php/conf.d/error_reporting.ini
+      - ./../tests/_output:/opt/phpstorm-coverage/
     networks:
       - default
 
diff --git a/psalm.xml b/psalm.xml
index 1a3425c..df94f78 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -20,7 +20,7 @@
         <directory name="./tests" useStrictTypes="true"/>
         <ignoreFiles>
             <directory name="./vendor"/>
-            <directory name="./tests/output"/>
+            <directory name="./tests/_output"/>
         </ignoreFiles>
     </projectFiles>
     <plugins>
diff --git a/src/Dto.php b/src/Dto.php
index 9f48a52..a9c33fa 100644
--- a/src/Dto.php
+++ b/src/Dto.php
@@ -22,6 +22,7 @@
 use Dto\Exception\Internal\EnumBackingValueException;
 use Error;
 use InvalidArgumentException;
+use KeyNormalizer\KeyNormalizer;
 use ReflectionClass;
 use ReflectionException;
 use ReflectionNamedType;
@@ -112,7 +113,7 @@ public function __call(string $name, array $arguments): mixed
         return $this->{$property};
     }
 
-    public function toArray(): array
+    public function toArray(KeyCase $keyCase = KeyCase::CAMEL_CASE): array
     {
         $properties = (new ReflectionClass($this))->getProperties(ReflectionProperty::IS_PROTECTED);
 
@@ -123,8 +124,13 @@ public function toArray(): array
             $property->setAccessible(true);
             $value = $property->getValue($this);
 
-            $data[$property->getName()] = is_a($value, Arrayable::class)
-                ? $value->toArray()
+            $key = match ($keyCase) {
+                KeyCase::SNAKE_CASE => KeyNormalizer::toSnakeCase($property->getName()),
+                KeyCase::CAMEL_CASE => $property->getName(),
+            };
+
+            $data[$key] = is_a($value, Arrayable::class)
+                ? is_a($value, self::class) ? $value->toArray($keyCase) : $value->toArray()
                 : $value;
         }
 
diff --git a/src/KeyCase.php b/src/KeyCase.php
new file mode 100644
index 0000000..222440c
--- /dev/null
+++ b/src/KeyCase.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dto;
+
+enum KeyCase
+{
+    case CAMEL_CASE;
+    case SNAKE_CASE;
+}
diff --git a/tests/DtoTest.php b/tests/DtoTest.php
index 482e3da..f6d6120 100644
--- a/tests/DtoTest.php
+++ b/tests/DtoTest.php
@@ -8,10 +8,12 @@
 use Dto\Exception\DtoException;
 use Dto\Exception\DtoException\HandleDtoException\GetValueException;
 use Dto\Exception\DtoException\SetupDtoException\InputDataException;
+use Dto\KeyCase;
 use PHPUnit\Framework\TestCase;
 use Tests\Fixtures\InfoArrayable;
 use Tests\Fixtures\PersonDto;
 use Tests\Fixtures\ProductDto;
+use Tests\Fixtures\SnakeCaseNestedDto;
 
 use function is_a;
 use function sprintf;
@@ -304,4 +306,54 @@ public function dpInvalidMethod(): array
             ],
         ];
     }
+
+    /**
+     * @group +
+     * @dataProvider dpTestToArray
+     */
+    public function testToArray(KeyCase $keyCase, array $expected): void
+    {
+        $data = [
+            'snakeCase' => [
+                'actualNumber' => 5,
+                'listInfo' => ['First random string', 'Second random string'],
+                'infoArrayable' => new InfoArrayable(),
+            ],
+            'actualNumber' => 10,
+            'providerName' => 'Main provider',
+        ];
+
+        $dto = new SnakeCaseNestedDto($data);
+        $this->assertEquals($expected, $dto->toArray($keyCase));
+    }
+
+    public static function dpTestToArray(): array
+    {
+        return [
+            [
+                KeyCase::CAMEL_CASE,
+                [
+                    'snakeCase' => [
+                        'actualNumber' => 5,
+                        'listInfo' => ['First random string', 'Second random string'],
+                        'infoArrayable' => ['camelCaseKey' => 'value'],
+                    ],
+                    'actualNumber' => 10,
+                    'providerName' => 'Main provider',
+                ],
+            ],
+            [
+                KeyCase::SNAKE_CASE,
+                [
+                    'snake_case' => [
+                        'actual_number' => 5,
+                        'list_info' => ['First random string', 'Second random string'],
+                        'info_arrayable' => ['camelCaseKey' => 'value'],
+                    ],
+                    'actual_number' => 10,
+                    'provider_name' => 'Main provider',
+                ],
+            ],
+        ];
+    }
 }
diff --git a/tests/Fixtures/InfoArrayable.php b/tests/Fixtures/InfoArrayable.php
index e597808..c69b305 100644
--- a/tests/Fixtures/InfoArrayable.php
+++ b/tests/Fixtures/InfoArrayable.php
@@ -10,6 +10,6 @@ class InfoArrayable implements Arrayable
 {
     public function toArray(): array
     {
-        return ['key' => 'value'];
+        return ['camelCaseKey' => 'value'];
     }
 }
diff --git a/tests/Fixtures/SnakeCaseDto.php b/tests/Fixtures/SnakeCaseDto.php
new file mode 100644
index 0000000..eb45160
--- /dev/null
+++ b/tests/Fixtures/SnakeCaseDto.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Fixtures;
+
+use Dto\Dto;
+
+/**
+ * @method int getActualNumber()
+ * @method array getListInfo()
+ * @method array getInfoArrayable()
+ * @psalm-suppress PossiblyUnusedProperty
+ * @psalm-suppress PropertyNotSetInConstructor
+ */
+class SnakeCaseDto extends Dto
+{
+    protected int $actualNumber;
+    protected array $listInfo;
+    protected array $infoArrayable;
+}
diff --git a/tests/Fixtures/SnakeCaseNestedDto.php b/tests/Fixtures/SnakeCaseNestedDto.php
new file mode 100644
index 0000000..a581fba
--- /dev/null
+++ b/tests/Fixtures/SnakeCaseNestedDto.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Fixtures;
+
+use Dto\Dto;
+
+/**
+ * @method ProductDto getProduct()
+ * @method int getActualNumber()
+ * @method string getProviderName()
+ * @psalm-suppress PossiblyUnusedProperty
+ * @psalm-suppress PropertyNotSetInConstructor
+ */
+class SnakeCaseNestedDto extends Dto
+{
+    protected SnakeCaseDto $snakeCase;
+    protected int $actualNumber;
+    protected string $providerName;
+}
diff --git a/tests/output/.gitkeep b/tests/_output/.gitkeep
similarity index 100%
rename from tests/output/.gitkeep
rename to tests/_output/.gitkeep