diff --git a/src/Responses/Chat/CreateResponse.php b/src/Responses/Chat/CreateResponse.php
index 57c1b654..88cb5c4a 100644
--- a/src/Responses/Chat/CreateResponse.php
+++ b/src/Responses/Chat/CreateResponse.php
@@ -12,7 +12,7 @@
 use OpenAI\Testing\Responses\Concerns\Fakeable;
 
 /**
- * @implements ResponseContract<array{id: string, object: string, created: int, model: string, system_fingerprint?: string, choices: array<int, array{index: int, message: array{role: string, content: string|null, function_call?: array{name: string, arguments: string}, tool_calls?: array<int, array{id: string, type: string, function: array{name: string, arguments: string}}>}, logprobs: ?array{content: ?array<int, array{token: string, logprob: float, bytes: ?array<int, int>}>}, finish_reason: string|null}>, usage: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int}}>
+ * @implements ResponseContract<array{id?: string, object: string, created: int, model: string, system_fingerprint?: string, choices: array<int, array{index: int, message: array{role: string, content: string|null, function_call?: array{name: string, arguments: string}, tool_calls?: array<int, array{id: string, type: string, function: array{name: string, arguments: string}}>}, logprobs: ?array{content: ?array<int, array{token: string, logprob: float, bytes: ?array<int, int>}>}, finish_reason: string|null}>, usage?: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int}}>
  */
 final class CreateResponse implements ResponseContract, ResponseHasMetaInformationContract
 {
@@ -28,20 +28,20 @@ final class CreateResponse implements ResponseContract, ResponseHasMetaInformati
      * @param  array<int, CreateResponseChoice>  $choices
      */
     private function __construct(
-        public readonly string $id,
+        public readonly ?string $id,
         public readonly string $object,
         public readonly int $created,
         public readonly string $model,
         public readonly ?string $systemFingerprint,
         public readonly array $choices,
-        public readonly CreateResponseUsage $usage,
+        public readonly ?CreateResponseUsage $usage,
         private readonly MetaInformation $meta,
     ) {}
 
     /**
      * Acts as static factory, and returns a new Response instance.
      *
-     * @param  array{id: string, object: string, created: int, model: string, system_fingerprint?: string, choices: array<int, array{index: int, message: array{role: string, content: ?string, function_call: ?array{name: string, arguments: string}, tool_calls: ?array<int, array{id: string, type: string, function: array{name: string, arguments: string}}>}, logprobs: ?array{content: ?array<int, array{token: string, logprob: float, bytes: ?array<int, int>}>}, finish_reason: string|null}>, usage: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int, prompt_tokens_details?:array{cached_tokens:int}, completion_tokens_details?:array{audio_tokens?:int, reasoning_tokens:int, accepted_prediction_tokens:int, rejected_prediction_tokens:int}}}  $attributes
+     * @param  array{id?: string, object: string, created: int, model: string, system_fingerprint?: string, choices: array<int, array{index: int, message: array{role: string, content: ?string, function_call: ?array{name: string, arguments: string}, tool_calls: ?array<int, array{id: string, type: string, function: array{name: string, arguments: string}}>}, logprobs: ?array{content: ?array<int, array{token: string, logprob: float, bytes: ?array<int, int>}>}, finish_reason: string|null}>, usage?: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int, prompt_tokens_details?:array{cached_tokens:int}, completion_tokens_details?:array{audio_tokens?:int, reasoning_tokens:int, accepted_prediction_tokens:int, rejected_prediction_tokens:int}}}  $attributes
      */
     public static function from(array $attributes, MetaInformation $meta): self
     {
@@ -50,13 +50,13 @@ public static function from(array $attributes, MetaInformation $meta): self
         ), $attributes['choices']);
 
         return new self(
-            $attributes['id'],
+            $attributes['id'] ?? null,
             $attributes['object'],
             $attributes['created'],
             $attributes['model'],
             $attributes['system_fingerprint'] ?? null,
             $choices,
-            CreateResponseUsage::from($attributes['usage']),
+            isset($attributes['usage']) ? CreateResponseUsage::from($attributes['usage']) : null,
             $meta,
         );
     }
@@ -76,7 +76,7 @@ public function toArray(): array
                 static fn (CreateResponseChoice $result): array => $result->toArray(),
                 $this->choices,
             ),
-            'usage' => $this->usage->toArray(),
+            'usage' => $this->usage?->toArray(),
         ], fn (mixed $value): bool => ! is_null($value));
     }
 }
diff --git a/src/Responses/Chat/CreateStreamedResponse.php b/src/Responses/Chat/CreateStreamedResponse.php
index adce31d7..6eb06ec6 100644
--- a/src/Responses/Chat/CreateStreamedResponse.php
+++ b/src/Responses/Chat/CreateStreamedResponse.php
@@ -9,7 +9,7 @@
 use OpenAI\Testing\Responses\Concerns\FakeableForStreamedResponse;
 
 /**
- * @implements ResponseContract<array{id: string, object: string, created: int, model: string, choices: array<int, array{index: int, delta: array{role?: string, content?: string}|array{role?: string, content: null, function_call: array{name?: string, arguments?: string}}, finish_reason: string|null}>, usage?: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int}}>
+ * @implements ResponseContract<array{id?: string, object: string, created: int, model: string, choices: array<int, array{index: int, delta: array{role?: string, content?: string}|array{role?: string, content: null, function_call: array{name?: string, arguments?: string}}, finish_reason: string|null}>, usage?: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int}}>
  */
 final class CreateStreamedResponse implements ResponseContract
 {
@@ -24,7 +24,7 @@ final class CreateStreamedResponse implements ResponseContract
      * @param  array<int, CreateStreamedResponseChoice>  $choices
      */
     private function __construct(
-        public readonly string $id,
+        public readonly ?string $id,
         public readonly string $object,
         public readonly int $created,
         public readonly string $model,
@@ -35,7 +35,7 @@ private function __construct(
     /**
      * Acts as static factory, and returns a new Response instance.
      *
-     * @param  array{id: string, object: string, created: int, model: string, choices: array<int, array{index: int, delta: array{role?: string, content?: string}, finish_reason: string|null}>, usage?: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int}}  $attributes
+     * @param  array{id?: string, object: string, created: int, model: string, choices: array<int, array{index: int, delta: array{role?: string, content?: string}, finish_reason: string|null}>, usage?: array{prompt_tokens: int, completion_tokens: int|null, total_tokens: int}}  $attributes
      */
     public static function from(array $attributes): self
     {
@@ -44,7 +44,7 @@ public static function from(array $attributes): self
         ), $attributes['choices']);
 
         return new self(
-            $attributes['id'],
+            $attributes['id'] ?? null,
             $attributes['object'],
             $attributes['created'],
             $attributes['model'],
@@ -58,7 +58,7 @@ public static function from(array $attributes): self
      */
     public function toArray(): array
     {
-        $data = [
+        return array_filter([
             'id' => $this->id,
             'object' => $this->object,
             'created' => $this->created,
@@ -67,12 +67,7 @@ public function toArray(): array
                 static fn (CreateStreamedResponseChoice $result): array => $result->toArray(),
                 $this->choices,
             ),
-        ];
-
-        if ($this->usage instanceof \OpenAI\Responses\Chat\CreateResponseUsage) {
-            $data['usage'] = $this->usage->toArray();
-        }
-
-        return $data;
+            'usage' => $this->usage?->toArray(),
+        ], fn (mixed $value): bool => ! is_null($value));
     }
 }
diff --git a/src/Responses/Embeddings/CreateResponse.php b/src/Responses/Embeddings/CreateResponse.php
index 7c734f12..0bd29104 100644
--- a/src/Responses/Embeddings/CreateResponse.php
+++ b/src/Responses/Embeddings/CreateResponse.php
@@ -12,12 +12,12 @@
 use OpenAI\Testing\Responses\Concerns\Fakeable;
 
 /**
- * @implements ResponseContract<array{object: string, data: array<int, array{object: string, embedding: array<int, float>, index: int}>, usage: array{prompt_tokens: int, total_tokens: int}}>
+ * @implements ResponseContract<array{object: string, data: array<int, array{object: string, embedding: array<int, float>, index?: int}>, usage?: array{prompt_tokens: int, total_tokens: int}}>
  */
 final class CreateResponse implements ResponseContract, ResponseHasMetaInformationContract
 {
     /**
-     * @use ArrayAccessible<array{object: string, data: array<int, array{object: string, embedding: array<int, float>, index: int}>, usage: array{prompt_tokens: int, total_tokens: int}}>
+     * @use ArrayAccessible<array{object: string, data: array<int, array{object: string, embedding: array<int, float>, index?: int}>, usage?: array{prompt_tokens: int, total_tokens: int}}>
      */
     use ArrayAccessible;
 
@@ -30,14 +30,14 @@ final class CreateResponse implements ResponseContract, ResponseHasMetaInformati
     private function __construct(
         public readonly string $object,
         public readonly array $embeddings,
-        public readonly CreateResponseUsage $usage,
+        public readonly ?CreateResponseUsage $usage,
         private readonly MetaInformation $meta,
     ) {}
 
     /**
      * Acts as static factory, and returns a new Response instance.
      *
-     * @param  array{object: string, data: array<int, array{object: string, embedding: array<int, float>, index: int}>, usage: array{prompt_tokens: int, total_tokens: int}}  $attributes
+     * @param  array{object: string, data: array<int, array{object: string, embedding: array<int, float>, index?: int}>, usage?: array{prompt_tokens: int, total_tokens: int}}  $attributes
      */
     public static function from(array $attributes, MetaInformation $meta): self
     {
@@ -48,7 +48,7 @@ public static function from(array $attributes, MetaInformation $meta): self
         return new self(
             $attributes['object'],
             $embeddings,
-            CreateResponseUsage::from($attributes['usage']),
+            isset($attributes['usage']) ? CreateResponseUsage::from($attributes['usage']) : null,
             $meta,
         );
     }
@@ -58,13 +58,13 @@ public static function from(array $attributes, MetaInformation $meta): self
      */
     public function toArray(): array
     {
-        return [
+        return array_filter([
             'object' => $this->object,
             'data' => array_map(
                 static fn (CreateResponseEmbedding $result): array => $result->toArray(),
                 $this->embeddings,
             ),
-            'usage' => $this->usage->toArray(),
-        ];
+            'usage' => $this->usage?->toArray(),
+        ], fn (mixed $value): bool => ! is_null($value));
     }
 }
diff --git a/src/Responses/Embeddings/CreateResponseEmbedding.php b/src/Responses/Embeddings/CreateResponseEmbedding.php
index 2c6c4635..c62b1c65 100644
--- a/src/Responses/Embeddings/CreateResponseEmbedding.php
+++ b/src/Responses/Embeddings/CreateResponseEmbedding.php
@@ -11,31 +11,31 @@ final class CreateResponseEmbedding
      */
     private function __construct(
         public readonly string $object,
-        public readonly int $index,
+        public readonly ?int $index,
         public readonly array $embedding,
     ) {}
 
     /**
-     * @param  array{object: string, index: int, embedding: array<int, float>}  $attributes
+     * @param  array{object: string, index?: int, embedding: array<int, float>}  $attributes
      */
     public static function from(array $attributes): self
     {
         return new self(
             $attributes['object'],
-            $attributes['index'],
+            $attributes['index'] ?? null,
             $attributes['embedding'],
         );
     }
 
     /**
-     * @return array{object: string, index: int, embedding: array<int, float>}
+     * @return array{object: string, index?: int, embedding: array<int, float>}
      */
     public function toArray(): array
     {
-        return [
+        return array_filter([
             'object' => $this->object,
             'index' => $this->index,
             'embedding' => $this->embedding,
-        ];
+        ], fn (mixed $value): bool => ! is_null($value));
     }
 }
diff --git a/tests/Fixtures/Chat.php b/tests/Fixtures/Chat.php
index a15795df..f19b14e6 100644
--- a/tests/Fixtures/Chat.php
+++ b/tests/Fixtures/Chat.php
@@ -37,6 +37,64 @@ function chatCompletion(): array
     ];
 }
 
+/**
+ * @return array<string, mixed>
+ */
+function chatCompletionWithoutId(): array
+{
+    return [
+        'object' => 'chat.completion',
+        'created' => 1677652288,
+        'model' => 'gpt-3.5-turbo',
+        'choices' => [
+            [
+                'index' => 0,
+                'message' => [
+                    'role' => 'assistant',
+                    'content' => "\n\nHello there, how may I assist you today?",
+                ],
+                'finish_reason' => 'stop',
+            ],
+        ],
+        'usage' => [
+            'prompt_tokens' => 9,
+            'completion_tokens' => 12,
+            'total_tokens' => 21,
+            'prompt_tokens_details' => [
+                'cached_tokens' => 5,
+            ],
+            'completion_tokens_details' => [
+                'reasoning_tokens' => 0,
+                'accepted_prediction_tokens' => 0,
+                'rejected_prediction_tokens' => 0,
+            ],
+        ],
+    ];
+}
+
+/**
+ * @return array<string, mixed>
+ */
+function chatCompletionWithoutUsage(): array
+{
+    return [
+        'id' => 'chatcmpl-123',
+        'object' => 'chat.completion',
+        'created' => 1677652288,
+        'model' => 'gpt-3.5-turbo',
+        'choices' => [
+            [
+                'index' => 0,
+                'message' => [
+                    'role' => 'assistant',
+                    'content' => "\n\nHello there, how may I assist you today?",
+                ],
+                'finish_reason' => 'stop',
+            ],
+        ],
+    ];
+}
+
 /**
  * @return array<string, mixed>
  */
@@ -242,6 +300,24 @@ function chatCompletionStreamFirstChunk(): array
     ];
 }
 
+function chatCompletionStreamFirstChunkWithoutId(): array
+{
+    return [
+        'object' => 'chat.completion.chunk',
+        'created' => 1679432086,
+        'model' => 'gpt-4-0314',
+        'choices' => [
+            [
+                'index' => 0,
+                'delta' => [
+                    'role' => 'assistant',
+                ],
+                'finish_reason' => null,
+            ],
+        ],
+    ];
+}
+
 function chatCompletionStreamContentChunk(): array
 {
     return [
diff --git a/tests/Fixtures/Embedding.php b/tests/Fixtures/Embedding.php
index 659f6a69..dbddee7e 100644
--- a/tests/Fixtures/Embedding.php
+++ b/tests/Fixtures/Embedding.php
@@ -16,6 +16,21 @@ function embedding(): array
     ];
 }
 
+/**
+ * @return array<string, mixed>
+ */
+function embeddingWithoutIndex(): array
+{
+    return [
+        'object' => 'embedding',
+        'embedding' => [
+            -0.008906792,
+            -0.013743395,
+            0.009874112,
+        ],
+    ];
+}
+
 /**
  * @return array<string, mixed>
  */
@@ -33,3 +48,17 @@ function embeddingList(): array
         ],
     ];
 }
+
+/**
+ * @return array<string, mixed>
+ */
+function embeddingListWithoutUsage(): array
+{
+    return [
+        'object' => 'list',
+        'data' => [
+            embedding(),
+            embedding(),
+        ],
+    ];
+}
diff --git a/tests/Responses/Chat/CreateResponse.php b/tests/Responses/Chat/CreateResponse.php
index 565d72c0..caafedf5 100644
--- a/tests/Responses/Chat/CreateResponse.php
+++ b/tests/Responses/Chat/CreateResponse.php
@@ -21,6 +21,38 @@
         ->meta()->toBeInstanceOf(MetaInformation::class);
 });
 
+test('from without id', function () {
+    $completion = CreateResponse::from(chatCompletionWithoutId(), meta());
+
+    expect($completion)
+        ->toBeInstanceOf(CreateResponse::class)
+        ->id->toBeNull()
+        ->object->toBe('chat.completion')
+        ->created->toBe(1677652288)
+        ->model->toBe('gpt-3.5-turbo')
+        ->systemFingerprint->toBeNull()
+        ->choices->toBeArray()->toHaveCount(1)
+        ->choices->each->toBeInstanceOf(CreateResponseChoice::class)
+        ->usage->toBeInstanceOf(CreateResponseUsage::class)
+        ->meta()->toBeInstanceOf(MetaInformation::class);
+});
+
+test('from without usage', function () {
+    $completion = CreateResponse::from(chatCompletionWithoutUsage(), meta());
+
+    expect($completion)
+        ->toBeInstanceOf(CreateResponse::class)
+        ->id->toBe('chatcmpl-123')
+        ->object->toBe('chat.completion')
+        ->created->toBe(1677652288)
+        ->model->toBe('gpt-3.5-turbo')
+        ->systemFingerprint->toBeNull()
+        ->choices->toBeArray()->toHaveCount(1)
+        ->choices->each->toBeInstanceOf(CreateResponseChoice::class)
+        ->usage->toBeNull()
+        ->meta()->toBeInstanceOf(MetaInformation::class);
+});
+
 test('from with system fingerprint', function () {
     $completion = CreateResponse::from(chatCompletionWithSystemFingerprint(), meta());
 
diff --git a/tests/Responses/Chat/CreateStreamedResponse.php b/tests/Responses/Chat/CreateStreamedResponse.php
index 4995400b..80a09e54 100644
--- a/tests/Responses/Chat/CreateStreamedResponse.php
+++ b/tests/Responses/Chat/CreateStreamedResponse.php
@@ -17,6 +17,19 @@
         ->choices->each->toBeInstanceOf(CreateStreamedResponseChoice::class);
 });
 
+test('from without id', function () {
+    $completion = CreateStreamedResponse::from(chatCompletionStreamFirstChunkWithoutId());
+
+    expect($completion)
+        ->toBeInstanceOf(CreateStreamedResponse::class)
+        ->id->toBeNull()
+        ->object->toBe('chat.completion.chunk')
+        ->created->toBe(1679432086)
+        ->model->toBe('gpt-4-0314')
+        ->choices->toBeArray()->toHaveCount(1)
+        ->choices->each->toBeInstanceOf(CreateStreamedResponseChoice::class);
+});
+
 test('from usage chunk', function () {
     $completion = CreateStreamedResponse::from(chatCompletionStreamUsageChunk());
 
diff --git a/tests/Responses/Embeddings/CreateResponse.php b/tests/Responses/Embeddings/CreateResponse.php
index 8c6b120a..0266bd1b 100644
--- a/tests/Responses/Embeddings/CreateResponse.php
+++ b/tests/Responses/Embeddings/CreateResponse.php
@@ -2,6 +2,7 @@
 
 use OpenAI\Responses\Embeddings\CreateResponse;
 use OpenAI\Responses\Embeddings\CreateResponseEmbedding;
+use OpenAI\Responses\Embeddings\CreateResponseUsage;
 use OpenAI\Responses\Meta\MetaInformation;
 
 test('from', function () {
@@ -12,6 +13,19 @@
         ->object->toBe('list')
         ->embeddings->toBeArray()->toHaveCount(2)
         ->embeddings->each->toBeInstanceOf(CreateResponseEmbedding::class)
+        ->usage->toBeInstanceOf(CreateResponseUsage::class)
+        ->meta()->toBeInstanceOf(MetaInformation::class);
+});
+
+test('from without usage', function () {
+    $response = CreateResponse::from(embeddingListWithoutUsage(), meta());
+
+    expect($response)
+        ->toBeInstanceOf(CreateResponse::class)
+        ->object->toBe('list')
+        ->embeddings->toBeArray()->toHaveCount(2)
+        ->embeddings->each->toBeInstanceOf(CreateResponseEmbedding::class)
+        ->usage->toBeNull()
         ->meta()->toBeInstanceOf(MetaInformation::class);
 });
 
diff --git a/tests/Responses/Embeddings/CreateResponseEmbedding.php b/tests/Responses/Embeddings/CreateResponseEmbedding.php
index 220658aa..a5fed133 100644
--- a/tests/Responses/Embeddings/CreateResponseEmbedding.php
+++ b/tests/Responses/Embeddings/CreateResponseEmbedding.php
@@ -15,6 +15,19 @@
         ]);
 });
 
+test('from without index', function () {
+    $result = CreateResponseEmbedding::from(embeddingWithoutIndex());
+
+    expect($result)
+        ->object->toBe('embedding')
+        ->index->toBeNull()
+        ->embedding->toBeArray()->toBe([
+            -0.008906792,
+            -0.013743395,
+            0.009874112,
+        ]);
+});
+
 test('to array', function () {
     $result = CreateResponseEmbedding::from(embedding());