diff --git a/src/Definition/Loader/OpenApiDefinitionLoader.php b/src/Definition/Loader/OpenApiDefinitionLoader.php
index 5a5f40d..fdc9843 100644
--- a/src/Definition/Loader/OpenApiDefinitionLoader.php
+++ b/src/Definition/Loader/OpenApiDefinitionLoader.php
@@ -133,6 +133,7 @@ private function getOperations(array $paths, array $securitySchemes, array $filt
                         ->setTags($this->getTags($operation->tags))
                         ->setSecurities($this->getSecurities($securitySchemes, $requirements))
                         ->setExamples($this->getExamples($operation, $parameters))
+                        ->setExtensions($operation->getExtensions())
                 );
             }
         }
diff --git a/src/Definition/Operation.php b/src/Definition/Operation.php
index b5f406b..94a503c 100644
--- a/src/Definition/Operation.php
+++ b/src/Definition/Operation.php
@@ -43,6 +43,11 @@ final class Operation implements Filterable
 
     private OperationExamples $examples;
 
+    /**
+     * @var array<string, mixed>
+     */
+    private array $extensions;
+
     public function __construct(
         private readonly string $id,
         private readonly string $path,
@@ -200,6 +205,14 @@ public function setResponses(Responses $responses): self
         return $this;
     }
 
+    /**
+     * @return array<string, mixed> $extensions
+     */
+    public function getExtensions(): array
+    {
+        return $this->extensions;
+    }
+
     public function getResponse(int $status): ?Response
     {
         return $this->responses->get($status);
@@ -277,6 +290,16 @@ public function setExamples(OperationExamples $examples): self
         return $this;
     }
 
+    /**
+     * @param array<string, mixed> $extensions
+     */
+    public function setExtensions(array $extensions): self
+    {
+        $this->extensions = $extensions;
+
+        return $this;
+    }
+
     /**
      * @param array<int|string, string|int> $params
      *
diff --git a/src/Preparator/Config/Error400BadFormatsPreparatorConfig.php b/src/Preparator/Config/Error400BadFormatsPreparatorConfig.php
new file mode 100644
index 0000000..18e17d0
--- /dev/null
+++ b/src/Preparator/Config/Error400BadFormatsPreparatorConfig.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace APITester\Preparator\Config;
+
+final class Error400BadFormatsPreparatorConfig extends Error400PreparatorConfig
+{
+}
diff --git a/src/Preparator/Config/Error400BadTypesPreparatorConfig.php b/src/Preparator/Config/Error400BadTypesPreparatorConfig.php
new file mode 100644
index 0000000..0342fc6
--- /dev/null
+++ b/src/Preparator/Config/Error400BadTypesPreparatorConfig.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace APITester\Preparator\Config;
+
+final class Error400BadTypesPreparatorConfig extends Error400PreparatorConfig
+{
+}
diff --git a/src/Preparator/Config/Error400MissingRequiredFieldsPreparatorConfig.php b/src/Preparator/Config/Error400MissingRequiredFieldsPreparatorConfig.php
new file mode 100644
index 0000000..f2f2b15
--- /dev/null
+++ b/src/Preparator/Config/Error400MissingRequiredFieldsPreparatorConfig.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace APITester\Preparator\Config;
+
+final class Error400MissingRequiredFieldsPreparatorConfig extends Error400PreparatorConfig
+{
+}
diff --git a/src/Preparator/Config/Error400PreparatorConfig.php b/src/Preparator/Config/Error400PreparatorConfig.php
new file mode 100644
index 0000000..09b81ca
--- /dev/null
+++ b/src/Preparator/Config/Error400PreparatorConfig.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace APITester\Preparator\Config;
+
+abstract class Error400PreparatorConfig extends PreparatorConfig
+{
+    public bool $excludeOpenApiEndpoints = false;
+}
diff --git a/src/Preparator/Error400Preparator.php b/src/Preparator/Error400Preparator.php
index 125c043..1dac5be 100644
--- a/src/Preparator/Error400Preparator.php
+++ b/src/Preparator/Error400Preparator.php
@@ -12,8 +12,12 @@
 use APITester\Definition\Example\ResponseExample;
 use APITester\Definition\Operation;
 use APITester\Definition\Parameter;
+use APITester\Preparator\Config\Error400PreparatorConfig;
 use APITester\Test\TestCase;
 
+/**
+ * @property Error400PreparatorConfig $config
+ */
 abstract class Error400Preparator extends TestCasesPreparator
 {
     /**
@@ -23,7 +27,7 @@ protected function prepare(Operations $operations): iterable
     {
         /** @var iterable<array-key, TestCase> */
         return $operations
-            ->map(fn (Operation $op) => $this->prepareTestCases($op))
+            ->map(fn (Operation $operation) => $this->prepareTestCases($operation))
             ->flatten()
         ;
     }
@@ -118,6 +122,10 @@ protected function getStatusCode(): string
      */
     private function prepareTestCases(Operation $operation): array
     {
+        if ($this->config->excludeOpenApiEndpoints
+            && isset($operation->getExtensions()['x-usecase'])) {
+            return [];
+        }
         $requiredParams = $operation->getParameters(true);
 
         return array_merge(
diff --git a/tests/Preparator/Error400MissingRequiredFieldsPreparatorTest.php b/tests/Preparator/Error400MissingRequiredFieldsPreparatorTest.php
index 524573e..b762e1f 100644
--- a/tests/Preparator/Error400MissingRequiredFieldsPreparatorTest.php
+++ b/tests/Preparator/Error400MissingRequiredFieldsPreparatorTest.php
@@ -21,11 +21,13 @@ final class Error400MissingRequiredFieldsPreparatorTest extends \PHPUnit\Framewo
     /**
      * @dataProvider getData
      *
+     * @param array<string, array<mixed>> $config
      * @param TestCase[] $expected
      */
-    public function test(Api $api, array $expected): void
+    public function test(Api $api, array $expected, array $config = []): void
     {
         $preparator = new Error400MissingRequiredFieldsPreparator();
+        $preparator->configure($config);
         Assert::objectsEqual(
             $expected,
             $preparator->doPrepare($api->getOperations()),
@@ -163,5 +165,48 @@ public function getData(): iterable
                 ),
             ],
         ];
+
+        yield 'openapi endpoint is ignored' => [
+            Api::create()
+                ->addOperation(
+                    Operation::create(
+                        'test',
+                        '/test',
+                        'POST'
+                    )
+                        ->addRequestBody(
+                            (new Body(
+                                new Schema([
+                                    'type' => 'object',
+                                    'properties' => [
+                                        'foo' => [
+                                            'type' => 'string',
+                                        ],
+                                        'bar' => [
+                                            'type' => 'string',
+                                        ],
+                                    ],
+                                    'required' => ['foo'],
+                                ]),
+                                'application/json'
+                            ))
+                        )
+                        ->addExample(
+                            OperationExample::create('foo')
+                                ->setBodyContent([
+                                    'foo' => 'foo_body1',
+                                    'bar' => 'bar_body1',
+                                ])
+                                ->setQueryParameter('foo_query', 'foo1')
+                        )->setExtensions([
+                            'x-usecase' => 'UseCaseName',
+                        ])
+                ),
+            [
+            ],
+            [
+                'excludeOpenApiEndpoints' => true,
+            ],
+        ];
     }
 }