diff --git a/CHANGELOG.md b/CHANGELOG.md
index f99d188a..921abb0c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 5.5.0
++ DEPRECATED: removed dataAndroid and originalJsonAndroid from PurchasedItem. Use transaction receipt instead as it is the same object.
+
 ## 5.0.2
 + Replaced obfuscatedAccountIdAndroid with obfuscatedAccountId in request purchase method [#299](https://github.com/dooboolab/flutter_inapp_purchase/pull/299)
 
@@ -8,7 +11,7 @@
 + Support null safety [#275](https://github.com/dooboolab/flutter_inapp_purchase/pull/275)
 
 ## 4.0.2
-+ The dart side requires "introductoryPriceCyclesAndroid" to be a int [#268](https://github.com/dooboolab/flutter_inapp_purchase/pull/268)
++ The dart side requires "introductoryPriceCyclesAndroid" to be an int [#268](https://github.com/dooboolab/flutter_inapp_purchase/pull/268)
 
 ## 4.0.1
 + `platform` dep version `>=2.0.0 <4.0.0`
diff --git a/lib/flutter_inapp_purchase.dart b/lib/flutter_inapp_purchase.dart
index 80fe0acb..af9effe5 100644
--- a/lib/flutter_inapp_purchase.dart
+++ b/lib/flutter_inapp_purchase.dart
@@ -50,6 +50,11 @@ class FlutterInappPurchase {
     return instance;
   }
 
+  PlatformException get _platformException => PlatformException(
+        code: _platform.operatingSystem,
+        message: "platform not supported",
+      );
+
   @visibleForTesting
   FlutterInappPurchase.private(Platform platform, {http.Client? client})
       : _pf = platform,
@@ -59,8 +64,7 @@ class FlutterInappPurchase {
   ///
   /// eg, `Android 5.1.1`
   Future<String?> get platformVersion async {
-    final String? version = await _channel.invokeMethod('getPlatformVersion');
-    return version;
+    return _channel.invokeMethod<String>('getPlatformVersion');
   }
 
   /// Consumes all items on `Android`.
@@ -73,8 +77,8 @@ class FlutterInappPurchase {
     } else if (_platform.isIOS) {
       return 'no-ops in ios';
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// InitConnection prepare iap features for both `Android` and `iOS`.
@@ -84,52 +88,47 @@ class FlutterInappPurchase {
   Future<String?> get initConnection async {
     if (_platform.isAndroid) {
       await _setPurchaseListener();
-      final String? result = await _channel.invokeMethod('initConnection');
-      return result;
+      return _channel.invokeMethod<String>('initConnection');
     } else if (_platform.isIOS) {
       await _setPurchaseListener();
-      final String? result = await _channel.invokeMethod('canMakePayments');
-      return result;
+      return _channel.invokeMethod<String>('canMakePayments');
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Retrieves a list of products from the store on `Android` and `iOS`.
   ///
   /// `iOS` also returns subscriptions.
   Future<List<IAPItem>> getProducts(List<String> skus) async {
-    skus = skus.toList();
+    if (skus.isEmpty) return [];
     if (_platform.isAndroid) {
-      dynamic result = await _channel.invokeMethod(
+      final result = await _channel.invokeListMethod<Map>(
         'getItemsByType',
         <String, dynamic>{
           'type': EnumUtil.getValueString(_TypeInApp.inapp),
           'skus': skus,
         },
       );
-      return extractItems(result);
+      return extractItems(result ?? []);
     } else if (_platform.isIOS) {
-      dynamic result = await _channel.invokeMethod(
+      final result = await _channel.invokeListMethod(
         'getItems',
-        {
-          'skus': skus,
-        },
+        {'skus': skus},
       );
-
-      return extractItems(json.encode(result));
+      return extractItems(result ?? []);
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Retrieves subscriptions on `Android` and `iOS`.
   ///
   /// `iOS` also returns non-subscription products.
   Future<List<IAPItem>> getSubscriptions(List<String> skus) async {
-    skus = skus.toList();
+    if (skus.isEmpty) return [];
     if (_platform.isAndroid) {
-      dynamic result = await _channel.invokeMethod(
+      final result = await _channel.invokeListMethod(
         'getItemsByType',
         <String, dynamic>{
           'type': EnumUtil.getValueString(_TypeInApp.subs),
@@ -137,82 +136,73 @@ class FlutterInappPurchase {
         },
       );
 
-      return extractItems(result);
+      return extractItems(result ?? []);
     } else if (_platform.isIOS) {
-      dynamic result = await _channel.invokeMethod(
+      final result = await _channel.invokeListMethod(
         'getItems',
-        {
-          'skus': skus,
-        },
+        {'skus': skus},
       );
 
-      return extractItems(json.encode(result));
+      return extractItems(result ?? []);
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Retrieves the user's purchase history on `Android` and `iOS` regardless of consumption status.
   ///
   /// Purchase history includes all types of products.
   /// Identical to [getAvailablePurchases] on `iOS`.
-  Future<List<PurchasedItem>?> getPurchaseHistory() async {
+  Future<List<PurchasedItem>> getPurchaseHistory() async {
     if (_platform.isAndroid) {
-      Future<dynamic> getInappPurchaseHistory = _channel.invokeMethod(
+      final getInappPurchaseHistory = _channel.invokeListMethod(
         'getPurchaseHistoryByType',
-        <String, dynamic>{
-          'type': EnumUtil.getValueString(_TypeInApp.inapp),
-        },
+        <String, dynamic>{'type': EnumUtil.getValueString(_TypeInApp.inapp)},
       );
 
-      Future<dynamic> getSubsPurchaseHistory = _channel.invokeMethod(
+      final getSubsPurchaseHistory = _channel.invokeListMethod(
         'getPurchaseHistoryByType',
-        <String, dynamic>{
-          'type': EnumUtil.getValueString(_TypeInApp.subs),
-        },
+        <String, dynamic>{'type': EnumUtil.getValueString(_TypeInApp.subs)},
       );
 
-      List<dynamic> results =
+      final results =
           await Future.wait([getInappPurchaseHistory, getSubsPurchaseHistory]);
 
-      return results.reduce((result1, result2) =>
-          extractPurchased(result1)! + extractPurchased(result2)!);
+      return extractPurchased((results[0] ?? []) + (results[1] ?? []));
     } else if (_platform.isIOS) {
-      dynamic result = await _channel.invokeMethod('getAvailableItems');
+      final result = await _channel.invokeListMethod('getAvailableItems');
 
-      return extractPurchased(json.encode(result));
+      return extractPurchased(result ?? []);
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Get all non-consumed purchases made on `Android` and `iOS`.
   ///
   /// This is identical to [getPurchaseHistory] on `iOS`
-  Future<List<PurchasedItem>?> getAvailablePurchases() async {
+  Future<List<PurchasedItem>> getAvailablePurchases() async {
     if (_platform.isAndroid) {
-      dynamic result1 = await _channel.invokeMethod(
+      final getInAppAvailable = _channel.invokeListMethod(
         'getAvailableItemsByType',
-        <String, dynamic>{
-          'type': EnumUtil.getValueString(_TypeInApp.inapp),
-        },
+        <String, dynamic>{'type': EnumUtil.getValueString(_TypeInApp.inapp)},
       );
 
-      dynamic result2 = await _channel.invokeMethod(
+      final getSubsAvailable = _channel.invokeListMethod(
         'getAvailableItemsByType',
-        <String, dynamic>{
-          'type': EnumUtil.getValueString(_TypeInApp.subs),
-        },
+        <String, dynamic>{'type': EnumUtil.getValueString(_TypeInApp.subs)},
       );
 
-      return extractPurchased(result1)! + extractPurchased(result2)!;
+      final results = await Future.wait([getInAppAvailable, getSubsAvailable]);
+
+      return extractPurchased((results[0] ?? []) + (results[1] ?? []));
     } else if (_platform.isIOS) {
-      dynamic result = await _channel.invokeMethod('getAvailableItems');
+      final result = await _channel.invokeListMethod('getAvailableItems');
 
-      return extractPurchased(json.encode(result));
+      return extractPurchased(result ?? []);
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Request a purchase on `Android` or `iOS`.
@@ -227,7 +217,7 @@ class FlutterInappPurchase {
     String? obfuscatedProfileIdAndroid,
   }) async {
     if (_platform.isAndroid) {
-      return await _channel.invokeMethod('buyItemByType', <String, dynamic>{
+      return _channel.invokeMethod('buyItemByType', <String, dynamic>{
         'type': EnumUtil.getValueString(_TypeInApp.inapp),
         'sku': sku,
         'oldSku': null,
@@ -237,13 +227,13 @@ class FlutterInappPurchase {
         'purchaseToken': purchaseTokenAndroid,
       });
     } else if (_platform.isIOS) {
-      return await _channel.invokeMethod('buyProduct', <String, dynamic>{
+      return _channel.invokeMethod('buyProduct', <String, dynamic>{
         'sku': sku,
         'forUser': obfuscatedAccountId,
       });
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Request a subscription on `Android` or `iOS`.
@@ -262,7 +252,7 @@ class FlutterInappPurchase {
     String? purchaseTokenAndroid,
   }) async {
     if (_platform.isAndroid) {
-      return await _channel.invokeMethod('buyItemByType', <String, dynamic>{
+      return _channel.invokeMethod('buyItemByType', <String, dynamic>{
         'type': EnumUtil.getValueString(_TypeInApp.subs),
         'sku': sku,
         'oldSku': oldSkuAndroid,
@@ -272,12 +262,12 @@ class FlutterInappPurchase {
         'purchaseToken': purchaseTokenAndroid,
       });
     } else if (_platform.isIOS) {
-      return await _channel.invokeMethod('buyProduct', <String, dynamic>{
+      return _channel.invokeMethod('buyProduct', <String, dynamic>{
         'sku': sku,
       });
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Add Store Payment (iOS only)
@@ -286,8 +276,7 @@ class FlutterInappPurchase {
   /// @returns {Future<String>}
   Future<String?> getPromotedProductIOS() async {
     if (_platform.isIOS) {
-      String? result = await _channel.invokeMethod('getPromotedProduct');
-      return result;
+      return _channel.invokeMethod<String>('getPromotedProduct');
     }
     return null;
   }
@@ -300,8 +289,8 @@ class FlutterInappPurchase {
     if (_platform.isIOS) {
       return await _channel.invokeMethod('requestPromotedProduct');
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Buy product with offer
@@ -313,15 +302,17 @@ class FlutterInappPurchase {
     Map<String, dynamic> withOffer,
   ) async {
     if (_platform.isIOS) {
-      return await _channel
-          .invokeMethod('requestProductWithOfferIOS', <String, dynamic>{
-        'sku': sku,
-        'forUser': forUser,
-        'withOffer': withOffer,
-      });
+      return _channel.invokeMethod(
+        'requestProductWithOfferIOS',
+        <String, dynamic>{
+          'sku': sku,
+          'forUser': forUser,
+          'withOffer': withOffer,
+        },
+      );
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Buy product with quantity
@@ -332,14 +323,13 @@ class FlutterInappPurchase {
     int quantity,
   ) async {
     if (_platform.isIOS) {
-      return await _channel
-          .invokeMethod('requestPurchaseWithQuantity', <String, dynamic>{
-        'sku': sku,
-        'quantity': quantity,
-      });
+      return _channel.invokeMethod(
+        'requestPurchaseWithQuantity',
+        <String, dynamic>{'sku': sku, 'quantity': quantity},
+      );
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Get the pending purchases in IOS.
@@ -347,11 +337,9 @@ class FlutterInappPurchase {
   /// @returns {Future<List<PurchasedItem>>}
   Future<List<PurchasedItem>?> getPendingTransactionsIOS() async {
     if (_platform.isIOS) {
-      dynamic result = await _channel.invokeMethod(
-        'getPendingTransactions',
-      );
+      final result = await _channel.invokeListMethod('getPendingTransactions');
 
-      return extractPurchased(json.encode(result));
+      return extractPurchased(result ?? []);
     }
     return [];
   }
@@ -361,17 +349,15 @@ class FlutterInappPurchase {
   /// No effect on `iOS`, whose iap purchases are consumed at the time of purchase.
   Future<String?> acknowledgePurchaseAndroid(String token) async {
     if (_platform.isAndroid) {
-      String? result =
-          await _channel.invokeMethod('acknowledgePurchase', <String, dynamic>{
-        'token': token,
-      });
-
-      return result;
+      return _channel.invokeMethod<String>(
+        'acknowledgePurchase',
+        <String, dynamic>{'token': token},
+      );
     } else if (_platform.isIOS) {
       return 'no-ops in ios';
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Consumes a purchase on `Android`.
@@ -388,33 +374,27 @@ class FlutterInappPurchase {
   ///        break;
   Future<String?> consumePurchaseAndroid(String token) async {
     if (_platform.isAndroid) {
-      String? result =
-          await _channel.invokeMethod('consumeProduct', <String, dynamic>{
+      return _channel.invokeMethod<String>('consumeProduct', <String, dynamic>{
         'token': token,
       });
-      return result;
     } else if (_platform.isIOS) {
       return 'no-ops in ios';
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// End Play Store connection on `Android` and remove iap observer in `iOS`.
   ///
   /// Absolutely necessary to call this when done with the payment.
   Future<String?> get endConnection async {
-    if (_platform.isAndroid) {
-      final String? result = await _channel.invokeMethod('endConnection');
-      _removePurchaseListener();
-      return result;
-    } else if (_platform.isIOS) {
-      final String? result = await _channel.invokeMethod('endConnection');
+    if (_platform.isAndroid || _platform.isIOS) {
+      final result = await _channel.invokeMethod<String>('endConnection');
       _removePurchaseListener();
       return result;
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Finish a transaction on `iOS`.
@@ -426,44 +406,43 @@ class FlutterInappPurchase {
     if (_platform.isAndroid) {
       return 'no ops in android';
     } else if (_platform.isIOS) {
-      String? result =
-          await _channel.invokeMethod('finishTransaction', <String, dynamic>{
-        'transactionIdentifier': transactionId,
-      });
-      return result;
+      return _channel.invokeMethod<String>(
+        'finishTransaction',
+        <String, dynamic>{'transactionIdentifier': transactionId},
+      );
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Finish a transaction on both `android` and `iOS`.
   ///
   /// Call this after finalizing server-side validation of the reciept.
-  Future<String?> finishTransaction(PurchasedItem purchasedItem,
+  Future<PurchaseResult> finishTransaction(PurchasedItem purchasedItem,
       {bool isConsumable = false}) async {
     if (_platform.isAndroid) {
       if (isConsumable) {
-        String? result =
-            await _channel.invokeMethod('consumeProduct', <String, dynamic>{
-          'token': purchasedItem.purchaseToken,
-        });
-        return result;
+        final result = await _channel.invokeMapMethod(
+          'consumeProduct',
+          <String, dynamic>{'token': purchasedItem.purchaseToken},
+        );
+        return PurchaseResult.fromJSON(Map<String, dynamic>.from(result ?? {}));
       } else {
-        String? result = await _channel
-            .invokeMethod('acknowledgePurchase', <String, dynamic>{
-          'token': purchasedItem.purchaseToken,
-        });
-        return result;
+        final result = await _channel.invokeMapMethod(
+          'acknowledgePurchase',
+          <String, dynamic>{'token': purchasedItem.purchaseToken},
+        );
+        return PurchaseResult.fromJSON(Map<String, dynamic>.from(result ?? {}));
       }
     } else if (_platform.isIOS) {
-      String? result =
-          await _channel.invokeMethod('finishTransaction', <String, dynamic>{
-        'transactionIdentifier': purchasedItem.transactionId,
-      });
-      return result;
+      final result = await _channel.invokeMapMethod(
+        'finishTransaction',
+        <String, dynamic>{'transactionIdentifier': purchasedItem.transactionId},
+      );
+      return PurchaseResult.fromJSON(Map<String, dynamic>.from(result ?? {}));
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Clear all remaining transaction on `iOS`.
@@ -473,11 +452,10 @@ class FlutterInappPurchase {
     if (_platform.isAndroid) {
       return 'no-ops in android.';
     } else if (_platform.isIOS) {
-      String? result = await _channel.invokeMethod('clearTransaction');
-      return result;
+      return _channel.invokeMethod<String>('clearTransaction');
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Retrieves a list of products that have been attempted to purchase through the App Store `iOS` only.
@@ -486,13 +464,13 @@ class FlutterInappPurchase {
     if (_platform.isAndroid) {
       return <IAPItem>[];
     } else if (_platform.isIOS) {
-      dynamic result =
-          await _channel.invokeMethod('getAppStoreInitiatedProducts');
+      final result =
+          await _channel.invokeListMethod('getAppStoreInitiatedProducts');
 
-      return extractItems(json.encode(result));
+      return extractItems(result ?? []);
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Check if a subscription is active on `Android` and `iOS`.
@@ -506,10 +484,9 @@ class FlutterInappPurchase {
     Duration grace: const Duration(days: 3),
   }) async {
     if (_platform.isIOS) {
-      var history =
-          await (getPurchaseHistory() as FutureOr<List<PurchasedItem>>);
+      final history = await getPurchaseHistory();
 
-      for (var purchase in history) {
+      for (final purchase in history) {
         Duration difference =
             DateTime.now().difference(purchase.transactionDate!);
         if (difference.inMinutes <= (duration + grace).inMinutes &&
@@ -518,17 +495,16 @@ class FlutterInappPurchase {
 
       return false;
     } else if (_platform.isAndroid) {
-      var purchases =
-          await (getAvailablePurchases() as FutureOr<List<PurchasedItem>>);
+      var purchases = await getAvailablePurchases();
 
-      for (var purchase in purchases) {
+      for (final purchase in purchases) {
         if (purchase.productId == sku) return true;
       }
 
       return false;
     }
-    throw PlatformException(
-        code: _platform.operatingSystem, message: "platform not supported");
+
+    throw _platformException;
   }
 
   /// Validate receipt in ios
@@ -613,15 +589,15 @@ class FlutterInappPurchase {
     _channel.setMethodCallHandler((MethodCall call) {
       switch (call.method) {
         case "purchase-updated":
-          Map<String, dynamic> result = jsonDecode(call.arguments);
+          final result = Map<String, dynamic>.from(call.arguments ?? {});
           _purchaseController!.add(new PurchasedItem.fromJSON(result));
           break;
         case "purchase-error":
-          Map<String, dynamic> result = jsonDecode(call.arguments);
+          final result = Map<String, dynamic>.from(call.arguments ?? {});
           _purchaseErrorController!.add(new PurchaseResult.fromJSON(result));
           break;
         case "connection-updated":
-          Map<String, dynamic> result = jsonDecode(call.arguments);
+          final result = Map<String, dynamic>.from(call.arguments ?? {});
           _connectionController!.add(new ConnectionResult.fromJSON(result));
           break;
         case "iap-promoted-product":
diff --git a/lib/modules.dart b/lib/modules.dart
index 51a490bf..d111bc49 100644
--- a/lib/modules.dart
+++ b/lib/modules.dart
@@ -39,7 +39,7 @@ class IAPItem {
 
   final String? iconUrl;
   final String? originalJson;
-  final String originalPrice;
+  final double originalPrice;
 
   /// Create [IAPItem] from a Map that was previously JSON formatted
   IAPItem.fromJSON(Map<String, dynamic> json)
@@ -72,7 +72,7 @@ class IAPItem {
         signatureAndroid = json['signatureAndroid'] as String?,
         iconUrl = json['iconUrl'] as String?,
         originalJson = json['originalJson'] as String?,
-        originalPrice = json['originalPrice'].toString(),
+        originalPrice = json['originalPrice'],
         discountsIOS = _extractDiscountIOS(json['discounts']);
 
   /// wow, i find if i want to save a IAPItem, there is not "toJson" to cast it into String...
@@ -215,12 +215,14 @@ class PurchasedItem {
   final String? orderId;
 
   // Android only
-  final String? dataAndroid;
   final String? signatureAndroid;
   final bool? autoRenewingAndroid;
   final bool? isAcknowledgedAndroid;
   final PurchaseState? purchaseStateAndroid;
-  final String? originalJsonAndroid;
+  @deprecated
+  String? get originalJsonAndroid => transactionReceipt;
+  @deprecated
+  String? get dataAndroid => transactionReceipt;
 
   // iOS only
   final DateTime? originalTransactionDateIOS;
@@ -235,13 +237,11 @@ class PurchasedItem {
         transactionReceipt = json['transactionReceipt'] as String?,
         purchaseToken = json['purchaseToken'] as String?,
         orderId = json['orderId'] as String?,
-        dataAndroid = json['dataAndroid'] as String?,
         signatureAndroid = json['signatureAndroid'] as String?,
         isAcknowledgedAndroid = json['isAcknowledgedAndroid'] as bool?,
         autoRenewingAndroid = json['autoRenewingAndroid'] as bool?,
         purchaseStateAndroid =
             _decodePurchaseStateAndroid(json['purchaseStateAndroid'] as int?),
-        originalJsonAndroid = json['originalJsonAndroid'] as String?,
         originalTransactionDateIOS =
             _extractDate(json['originalTransactionDateIOS']),
         originalTransactionIdentifierIOS =
@@ -260,12 +260,10 @@ class PurchasedItem {
         'orderId: $orderId, '
 
         /// android specific
-        'dataAndroid: $dataAndroid, '
         'signatureAndroid: $signatureAndroid, '
         'isAcknowledgedAndroid: $isAcknowledgedAndroid, '
         'autoRenewingAndroid: $autoRenewingAndroid, '
         'purchaseStateAndroid: $purchaseStateAndroid, '
-        'originalJsonAndroid: $originalJsonAndroid, '
 
         /// ios specific
         'originalTransactionDateIOS: ${originalTransactionDateIOS?.toIso8601String()}, '
@@ -275,10 +273,9 @@ class PurchasedItem {
 
   /// Coerce miliseconds since epoch in double, int, or String into DateTime format
   static DateTime? _extractDate(dynamic timestamp) {
-    if (timestamp == null) return null;
+    if (timestamp == null || timestamp is! int) return null;
 
-    int _toInt() => double.parse(timestamp.toString()).toInt();
-    return DateTime.fromMillisecondsSinceEpoch(_toInt());
+    return DateTime.fromMillisecondsSinceEpoch(timestamp);
   }
 }
 
diff --git a/lib/utils.dart b/lib/utils.dart
index 96cff361..10223d8e 100644
--- a/lib/utils.dart
+++ b/lib/utils.dart
@@ -1,48 +1,29 @@
 import 'modules.dart';
-import 'dart:convert';
 
-List<IAPItem> extractItems(dynamic result) {
-  List list = json.decode(result.toString());
-  List<IAPItem> products = list
-      .map<IAPItem>(
-        (dynamic product) => IAPItem.fromJSON(product as Map<String, dynamic>),
-      )
+List<IAPItem> extractItems(List<dynamic> result) {
+  List<IAPItem> products = result
+      .map<IAPItem>((map) => IAPItem.fromJSON(Map<String, dynamic>.from(map)))
       .toList();
 
   return products;
 }
 
-List<PurchasedItem>? extractPurchased(dynamic result) {
-  List<PurchasedItem>? decoded = json
-      .decode(result.toString())
+List<PurchasedItem> extractPurchased(List<dynamic> result) {
+  final purhcased = result
       .map<PurchasedItem>(
-        (dynamic product) =>
-            PurchasedItem.fromJSON(product as Map<String, dynamic>),
-      )
-      .toList();
-
-  return decoded;
-}
-
-
-List<PurchaseResult>? extractResult(dynamic result) {
-  List<PurchaseResult>? decoded = json
-      .decode(result.toString())
-      .map<PurchaseResult>(
-        (dynamic product) =>
-            PurchaseResult.fromJSON(product as Map<String, dynamic>),
+        (product) => PurchasedItem.fromJSON(Map<String, dynamic>.from(product)),
       )
       .toList();
 
-  return decoded;
+  return purhcased;
 }
 
-
 class EnumUtil {
   /// return enum value
   ///
   /// example: enum Type {Hoge},
   /// String value = EnumUtil.getValueString(Type.Hoge);
   /// assert(value == "Hoge");
-  static String getValueString(dynamic enumType) => enumType.toString().split('.')[1];
+  static String getValueString(dynamic enumType) =>
+      enumType.toString().split('.')[1];
 }
diff --git a/test/flutter_inapp_purchase_test.dart b/test/flutter_inapp_purchase_test.dart
index 2a8aa0f6..2c7eda32 100644
--- a/test/flutter_inapp_purchase_test.dart
+++ b/test/flutter_inapp_purchase_test.dart
@@ -1,4 +1,3 @@
-import 'dart:async';
 import 'dart:convert';
 
 import 'package:flutter/services.dart';
@@ -161,13 +160,14 @@ void main() {
         final List<MethodCall> log = <MethodCall>[];
         List<String> skus = []..add("testsku");
 
-        final dynamic result = """[
+        final result = <Map>[
           {
             "productId": "com.cooni.point1000",
             "price": "120",
             "currency": "JPY",
             "localizedPrice": "¥120",
             "title": "1,000",
+            "originalPrice": 1.235862359273509,
             "description": "1000 points 1000P",
             "introductoryPrice": "1001",
             "introductoryPricePaymentModeIOS": "1002",
@@ -180,7 +180,7 @@ void main() {
             "introductoryPricePeriodAndroid": "5",
             "freeTrialPeriodAndroid": "6"
           }
-        ]""";
+        ];
 
         setUp(() {
           FlutterInappPurchase(FlutterInappPurchase.private(
@@ -213,9 +213,11 @@ void main() {
         test('returns correct result', () async {
           List<IAPItem> products =
               await FlutterInappPurchase.instance.getProducts(skus);
-          List<IAPItem> expected = (json.decode(result) as List)
+          List<IAPItem> expected = (result)
               .map<IAPItem>(
-                (product) => IAPItem.fromJSON(product as Map<String, dynamic>),
+                (product) => IAPItem.fromJSON(
+                  Map<String, dynamic>.from(product),
+                ),
               )
               .toList();
           for (var i = 0; i < products.length; ++i) {
@@ -260,6 +262,7 @@ void main() {
             "currency": "JPY",
             "localizedPrice": "¥120",
             "title": "1,000",
+            "originalPrice": 1.235862359273509,
             "description": "1000 points 1000P",
             "introductoryPrice": "1001",
             "introductoryPricePaymentModeIOS": "1002",
@@ -306,7 +309,9 @@ void main() {
               await FlutterInappPurchase.instance.getProducts(skus);
           List<IAPItem>? expected = result
               .map<IAPItem>(
-                (product) => IAPItem.fromJSON(product as Map<String, dynamic>),
+                (product) => IAPItem.fromJSON(
+                  Map<String, dynamic>.from(product),
+                ),
               )
               .toList();
           for (var i = 0; i < products.length; ++i) {
@@ -346,13 +351,14 @@ void main() {
         final List<MethodCall> log = <MethodCall>[];
         List<String> skus = []..add("testsku");
 
-        final dynamic result = """[
+        final result = <Map>[
           {
             "productId": "com.cooni.point1000",
             "price": "120",
             "currency": "JPY",
             "localizedPrice": "¥120",
             "title": "1,000",
+            "originalPrice": 1.235862359273509,
             "description": "1000 points 1000P",
             "introductoryPrice": "1001",
             "introductoryPricePaymentModeIOS": "1002",
@@ -365,7 +371,7 @@ void main() {
             "introductoryPricePeriodAndroid": "5",
             "freeTrialPeriodAndroid": "6"
           }
-        ]""";
+        ];
 
         setUp(() {
           FlutterInappPurchase(FlutterInappPurchase.private(
@@ -397,9 +403,10 @@ void main() {
         test('returns correct result', () async {
           List<IAPItem> products =
               await FlutterInappPurchase.instance.getSubscriptions(skus);
-          List<IAPItem> expected = (json.decode(result) as List)
+          List<IAPItem> expected = result
               .map<IAPItem>(
-                (product) => IAPItem.fromJSON(product as Map<String, dynamic>),
+                (product) =>
+                    IAPItem.fromJSON(Map<String, dynamic>.from(product)),
               )
               .toList();
           for (var i = 0; i < products.length; ++i) {
@@ -444,6 +451,7 @@ void main() {
             "currency": "JPY",
             "localizedPrice": "¥120",
             "title": "1,000",
+            "originalPrice": 1.235862359273509,
             "description": "1000 points 1000P",
             "introductoryPrice": "1001",
             "introductoryPricePaymentModeIOS": "1002",
@@ -490,7 +498,9 @@ void main() {
               await FlutterInappPurchase.instance.getSubscriptions(skus);
           List<IAPItem>? expected = result
               .map<IAPItem>(
-                (product) => IAPItem.fromJSON(product as Map<String, dynamic>),
+                (product) => IAPItem.fromJSON(
+                  Map<String, dynamic>.from(product),
+                ),
               )
               .toList();
           for (var i = 0; i < products.length; ++i) {
@@ -529,30 +539,36 @@ void main() {
       group('for Android', () {
         final List<MethodCall> log = <MethodCall>[];
 
-        final String resultInapp = """[{
-            "transactionDate":"1552824902000",
-            "transactionId":"testTransactionId",
-            "productId":"com.cooni.point1000",
-            "transactionReceipt":"testTransactionReciept",
-            "purchaseToken":"testPurchaseToken",
-            "autoRenewingAndroid":true,
-            "dataAndroid":"testDataAndroid",
-            "signatureAndroid":"testSignatureAndroid",
-            "originalTransactionDateIOS":"1552831136000",
-            "originalTransactionIdentifierIOS":"testOriginalTransactionIdentifierIOS"
-          }]""";
-        final String resultSubs = """[{
-            "transactionDate":"1552824902000",
-            "transactionId":"testSubsTransactionId",
-            "productId":"com.cooni.point1000.subs",
-            "transactionReceipt":"testSubsTransactionReciept",
-            "purchaseToken":"testSubsPurchaseToken",
-            "autoRenewingAndroid":true,
-            "dataAndroid":"testSubsDataAndroid",
-            "signatureAndroid":"testSubsSignatureAndroid",
-            "originalTransactionDateIOS":"1552831136000",
-            "originalTransactionIdentifierIOS":"testSubsOriginalTransactionIdentifierIOS"
-          }]""";
+        final resultInApp = <Map>[
+          {
+            "transactionDate": 1552824902000,
+            "transactionId": "testTransactionId",
+            "productId": "com.cooni.point1000",
+            "transactionReceipt": "testTransactionReciept",
+            "purchaseToken": "testPurchaseToken",
+            "autoRenewingAndroid": true,
+            "dataAndroid": "testDataAndroid",
+            "signatureAndroid": "testSignatureAndroid",
+            "originalTransactionDateIOS": 1552831136000,
+            "originalTransactionIdentifierIOS":
+                "testOriginalTransactionIdentifierIOS"
+          }
+        ];
+        final resultSubs = <Map>[
+          {
+            "transactionDate": 1552824902000,
+            "transactionId": "testSubsTransactionId",
+            "productId": "com.cooni.point1000.subs",
+            "transactionReceipt": "testSubsTransactionReciept",
+            "purchaseToken": "testSubsPurchaseToken",
+            "autoRenewingAndroid": true,
+            "dataAndroid": "testSubsDataAndroid",
+            "signatureAndroid": "testSubsSignatureAndroid",
+            "originalTransactionDateIOS": 1552831136000,
+            "originalTransactionIdentifierIOS":
+                "testSubsOriginalTransactionIdentifierIOS"
+          }
+        ];
 
         setUp(() {
           FlutterInappPurchase(FlutterInappPurchase.private(
@@ -563,7 +579,7 @@ void main() {
             log.add(methodCall);
             var m = methodCall.arguments as Map<dynamic, dynamic>;
             if (m['type'] == 'inapp') {
-              return resultInapp;
+              return resultInApp;
             } else if (m['type'] == 'subs') {
               return resultSubs;
             }
@@ -580,26 +596,21 @@ void main() {
           expect(log, <Matcher>[
             isMethodCall(
               'getPurchaseHistoryByType',
-              arguments: <String, dynamic>{
-                'type': 'inapp',
-              },
+              arguments: <String, dynamic>{'type': 'inapp'},
             ),
             isMethodCall(
               'getPurchaseHistoryByType',
-              arguments: <String, dynamic>{
-                'type': 'subs',
-              },
+              arguments: <String, dynamic>{'type': 'subs'},
             ),
           ]);
         });
 
         test('returns correct result', () async {
-          List<PurchasedItem>? actualList = await (FlutterInappPurchase.instance
-                  .getPurchaseHistory() as FutureOr<List<PurchasedItem>?>) ??
-              [];
-          List<PurchasedItem> expectList = ((json.decode(resultInapp) as List) +
-                  (json.decode(resultSubs) as List))
-              .map((item) => PurchasedItem.fromJSON(item))
+          List<PurchasedItem>? actualList =
+              await FlutterInappPurchase.instance.getPurchaseHistory();
+          List<PurchasedItem> expectList = (resultInApp + resultSubs)
+              .map((item) =>
+                  PurchasedItem.fromJSON(Map<String, dynamic>.from(item)))
               .toList();
 
           for (var i = 0; i < actualList.length; ++i) {
@@ -612,7 +623,6 @@ void main() {
             expect(actual.transactionReceipt, expected.transactionReceipt);
             expect(actual.purchaseToken, expected.purchaseToken);
             expect(actual.autoRenewingAndroid, expected.autoRenewingAndroid);
-            expect(actual.dataAndroid, expected.dataAndroid);
             expect(actual.signatureAndroid, expected.signatureAndroid);
             expect(actual.originalTransactionDateIOS,
                 expected.originalTransactionDateIOS);
@@ -680,9 +690,8 @@ void main() {
         });
 
         test('returns correct result', () async {
-          List<PurchasedItem>? actualList = await (FlutterInappPurchase.instance
-                  .getPurchaseHistory() as FutureOr<List<PurchasedItem>?>) ??
-              [];
+          List<PurchasedItem>? actualList =
+              await FlutterInappPurchase.instance.getPurchaseHistory();
           List<PurchasedItem>? expectList = result
               .map<PurchasedItem>((item) => PurchasedItem.fromJSON(item))
               .toList();
@@ -697,7 +706,6 @@ void main() {
             expect(actual.transactionReceipt, expected.transactionReceipt);
             expect(actual.purchaseToken, expected.purchaseToken);
             expect(actual.autoRenewingAndroid, expected.autoRenewingAndroid);
-            expect(actual.dataAndroid, expected.dataAndroid);
             expect(actual.signatureAndroid, expected.signatureAndroid);
             expect(actual.originalTransactionDateIOS,
                 expected.originalTransactionDateIOS);
@@ -711,31 +719,36 @@ void main() {
     group('getAvailablePurchases', () {
       group('for Android', () {
         final List<MethodCall> log = <MethodCall>[];
-
-        final String resultInapp = """[{
-            "transactionDate":"1552824902000",
-            "transactionId":"testTransactionId",
-            "productId":"com.cooni.point1000",
-            "transactionReceipt":"testTransactionReciept",
-            "purchaseToken":"testPurchaseToken",
-            "autoRenewingAndroid":true,
-            "dataAndroid":"testDataAndroid",
-            "signatureAndroid":"testSignatureAndroid",
-            "originalTransactionDateIOS":"1552831136000",
-            "originalTransactionIdentifierIOS":"testOriginalTransactionIdentifierIOS"
-          }]""";
-        final String resultSubs = """[{
-            "transactionDate":"1552824902000",
-            "transactionId":"testSubsTransactionId",
-            "productId":"com.cooni.point1000.subs",
-            "transactionReceipt":"testSubsTransactionReciept",
-            "purchaseToken":"testSubsPurchaseToken",
-            "autoRenewingAndroid":true,
-            "dataAndroid":"testSubsDataAndroid",
-            "signatureAndroid":"testSubsSignatureAndroid",
-            "originalTransactionDateIOS":"1552831136000",
-            "originalTransactionIdentifierIOS":"testSubsOriginalTransactionIdentifierIOS"
-          }]""";
+        final resultInApp = <Map>[
+          {
+            "transactionDate": 1552824902000,
+            "transactionId": "testTransactionId",
+            "productId": "com.cooni.point1000",
+            "transactionReceipt": "testTransactionReciept",
+            "purchaseToken": "testPurchaseToken",
+            "autoRenewingAndroid": true,
+            "dataAndroid": "testDataAndroid",
+            "signatureAndroid": "testSignatureAndroid",
+            "originalTransactionDateIOS": 1552831136000,
+            "originalTransactionIdentifierIOS":
+                "testOriginalTransactionIdentifierIOS"
+          }
+        ];
+        final resultSubs = <Map>[
+          {
+            "transactionDate": 1552824902000,
+            "transactionId": "testSubsTransactionId",
+            "productId": "com.cooni.point1000.subs",
+            "transactionReceipt": "testSubsTransactionReciept",
+            "purchaseToken": "testSubsPurchaseToken",
+            "autoRenewingAndroid": true,
+            "dataAndroid": "testSubsDataAndroid",
+            "signatureAndroid": "testSubsSignatureAndroid",
+            "originalTransactionDateIOS": 1552831136000,
+            "originalTransactionIdentifierIOS":
+                "testSubsOriginalTransactionIdentifierIOS"
+          }
+        ];
 
         setUp(() {
           FlutterInappPurchase(FlutterInappPurchase.private(
@@ -746,7 +759,7 @@ void main() {
             log.add(methodCall);
             var m = methodCall.arguments as Map<dynamic, dynamic>;
             if (m['type'] == 'inapp') {
-              return resultInapp;
+              return resultInApp;
             } else if (m['type'] == 'subs') {
               return resultSubs;
             }
@@ -777,12 +790,11 @@ void main() {
         });
 
         test('returns correct result', () async {
-          List<PurchasedItem>? actualList = await (FlutterInappPurchase.instance
-                  .getAvailablePurchases() as FutureOr<List<PurchasedItem>?>) ??
-              [];
-          List<PurchasedItem> expectList = ((json.decode(resultInapp) as List) +
-                  (json.decode(resultSubs) as List))
-              .map((item) => PurchasedItem.fromJSON(item))
+          List<PurchasedItem> actualList =
+              await FlutterInappPurchase.instance.getAvailablePurchases();
+          List<PurchasedItem> expectList = (resultInApp + resultSubs)
+              .map((item) =>
+                  PurchasedItem.fromJSON(Map<String, dynamic>.from(item)))
               .toList();
 
           for (var i = 0; i < actualList.length; ++i) {
@@ -795,7 +807,6 @@ void main() {
             expect(actual.transactionReceipt, expected.transactionReceipt);
             expect(actual.purchaseToken, expected.purchaseToken);
             expect(actual.autoRenewingAndroid, expected.autoRenewingAndroid);
-            expect(actual.dataAndroid, expected.dataAndroid);
             expect(actual.signatureAndroid, expected.signatureAndroid);
             expect(actual.originalTransactionDateIOS,
                 expected.originalTransactionDateIOS);
@@ -863,9 +874,8 @@ void main() {
         });
 
         test('returns correct result', () async {
-          List<PurchasedItem>? actualList = await (FlutterInappPurchase.instance
-                  .getAvailablePurchases() as FutureOr<List<PurchasedItem>?>) ??
-              [];
+          List<PurchasedItem>? actualList =
+              await FlutterInappPurchase.instance.getAvailablePurchases();
           List<PurchasedItem>? expectList = result
               .map<PurchasedItem>((item) =>
                   PurchasedItem.fromJSON(item as Map<String, dynamic>))
@@ -881,7 +891,6 @@ void main() {
             expect(actual.transactionReceipt, expected.transactionReceipt);
             expect(actual.purchaseToken, expected.purchaseToken);
             expect(actual.autoRenewingAndroid, expected.autoRenewingAndroid);
-            expect(actual.dataAndroid, expected.dataAndroid);
             expect(actual.signatureAndroid, expected.signatureAndroid);
             expect(actual.originalTransactionDateIOS,
                 expected.originalTransactionDateIOS);
@@ -1315,6 +1324,7 @@ void main() {
             "title": "1,000",
             "description": "1000 points 1000P",
             "introductoryPrice": "1001",
+            "originalPrice": 1.235862359273509,
             "introductoryPricePaymentModeIOS": "1002",
             "introductoryPriceNumberOfPeriodsIOS": "1003",
             "introductoryPriceSubscriptionPeriodIOS": "1004",
@@ -1353,7 +1363,9 @@ void main() {
               .getAppStoreInitiatedProducts();
           List<IAPItem>? expected = result
               .map<IAPItem>(
-                (product) => IAPItem.fromJSON(product as Map<String, dynamic>),
+                (product) => IAPItem.fromJSON(
+                  Map<String, dynamic>.from(product),
+                ),
               )
               .toList();
           for (var i = 0; i < products.length; ++i) {