diff --git a/demo/validate_api.php b/demo/validate_api.php
index 3c46cc7..f06e123 100644
--- a/demo/validate_api.php
+++ b/demo/validate_api.php
@@ -105,7 +105,7 @@ function print_result($response)
         $response->debug();
     }
     if ($showJson) {
-        $json = $response->getJson();
+        $json = json_decode($response->getJsonString());
         if ($json !== null) {
             print("\n");
             print(json_encode($json, JSON_PRETTY_PRINT));
diff --git a/public/api.php b/public/api.php
index db47b58..a579518 100644
--- a/public/api.php
+++ b/public/api.php
@@ -130,8 +130,8 @@ function logApiSuccess(string $url, object $response, array $context = []): void
 }
 
 $file = null;
-if ($response && method_exists($response, 'getJson')) {
-    $json_file = json_encode($response->getJson());
+if ($response instanceof \ubfr\c5tools\interfaces\JsonDocument) {
+    $json_file = $response->getJsonString();
     if ($json_file) {
         $compressed = gzcompress($json_file, 3);
         if ($compressed) {