options('/{routes:.*}', function (Request $request, Response $response) { // CORS Pre-Flight OPTIONS Request Handler return $response; }); $app->get('/', function (Request $request, Response $response) { $response->getBody()->write('Hello world!'); return $response; }); $app->group('/users', function (Group $group) { $group->get('', ListUsersAction::class); $group->get('/{id}', ViewUserAction::class); }); };