Validation not working on Laravel version 10

Here is my register method in my AuthController,

 public function register(Request $request)
 {
    $request->validate([
            'firstName' => 'required | string',
            'lastName' => 'required | string',
            'email'    => 'required | email | unique:users,email',
        ], [
            'email.unique' => 'User with this email already exists',
        ]);
 }

I'm using postman to send the API requests,

This is the API endpoint present in my routes.php,

Route::post('/register', [AuthController::class, 'register']);

However, when I send the POST request to this endpoint using postman some HTML content with a 200 response code returns back even though the fields are set to empty when sending. When I click the preview tab in postman it shows me Laravel home page.

if this is in routes.php then when you post through postman before this validation, csrf-token also need to be present else it will redirect back. which is not available in case of postman and you will see the home page as the redirected page.

Try adding header Accept: application/json to get the response in json format.

Also I suggest that the apis must defined in api.php in routes folder to remove session related validation on the api calls

so define your routes in api.php like

Route::post('/register', [AuthController::class, 'register']);

then call it through post as

http://localhost/project/api/register