diff --git a/lib/oto/commands/util/slack.dart b/lib/oto/commands/util/slack.dart
index 00b71c4..51858d2 100644
--- a/lib/oto/commands/util/slack.dart
+++ b/lib/oto/commands/util/slack.dart
@@ -18,19 +18,15 @@ class Slack extends Command {
     if (data.property != null) {
       var value = data.property as DataSlack?;
       if (value != null) {
-        await sender.sendData(value);
-      }
-      else
-      {
+        await sender.sendData(value); 
+      } else {
         throw Exception('The property is null.');
       }
-    }
-    else if(data.message != null) 
-    {
+    } else if(data.message != null) {
       await sender.send(jsonEncode(data.message));
-    }
-    else
-    {
+    } else if(data.messageJson != null) {
+      await sender.send(data.messageJson!);
+    } else {
       throw Exception('property or message field should not be null');
     }
 
diff --git a/lib/oto/commands/util/string_util.dart b/lib/oto/commands/util/string_util.dart
index 2796f98..601a73a 100644
--- a/lib/oto/commands/util/string_util.dart
+++ b/lib/oto/commands/util/string_util.dart
@@ -53,11 +53,12 @@ class StringReplacePattern extends Command {
   Future execute(DataCommand command) async {
     var data = DataStringReplacePattern.fromJson(getParam(command));
     
+    var startAt = data.startAt ?? 0;
     var text = data.text;
     var value = data.value;
     var exitCode = 0;
 
-    var start = text.indexOf(data.startPattern, data.startAt);
+    var start = text.indexOf(data.startPattern, startAt);
     var end = text.indexOf(data.endPattern, start);
     text = text.replaceRange(start, end + data.endPattern.length, value);
 
@@ -72,9 +73,10 @@ class StringIndex extends Command {
   Future execute(DataCommand command) async {
     var data = DataStringIndex.fromJson(getParam(command));
     
+    var startAt = data.startAt ?? 0;
     var text = data.text;
     var exitCode = 0;
-    var index = text.indexOf(data.value);
+    var index = text.indexOf(data.value, startAt);
 
     await setProperty(data.setValue, index, showPrint: data.showPrint);
 
diff --git a/lib/oto/data/command_data.dart b/lib/oto/data/command_data.dart
index 93a77c6..51becae 100644
--- a/lib/oto/data/command_data.dart
+++ b/lib/oto/data/command_data.dart
@@ -497,8 +497,9 @@ class DataSlackSender extends DataParam {
   DataSlackSender();
 
   late String token;
-  late dynamic property;
-  late Map<String, dynamic>? message;
+  late dynamic property; //oto 내부 생성된 object의 경우
+  late Map<String, dynamic>? message; //yaml로 선언된 값
+  late String? messageJson; //json값으로 선언된 값
 
   factory DataSlackSender.fromJson(Map<String, dynamic> json) =>
       _$DataSlackSenderFromJson(json);
@@ -955,7 +956,7 @@ class DataStringReplace extends DataParam {
 class DataStringReplacePattern extends DataParam {
   DataStringReplacePattern();
 
-  int startAt = 0;
+  int? startAt = 0;
   late String startPattern; //시작 패턴
   late String endPattern; //종료 패턴
   late String text; //원본 텍스트
@@ -973,7 +974,7 @@ class DataStringReplacePattern extends DataParam {
 class DataStringIndex extends DataParam {
   DataStringIndex();
 
-  int startAt = 0;
+  int? startAt = 0;
   late String text;
   late String value;
   late String setValue;
diff --git a/lib/oto/data/command_data.g.dart b/lib/oto/data/command_data.g.dart
index 469e613..049995d 100644
--- a/lib/oto/data/command_data.g.dart
+++ b/lib/oto/data/command_data.g.dart
@@ -867,7 +867,8 @@ DataSlackSender _$DataSlackSenderFromJson(Map<String, dynamic> json) =>
       ..showPrint = json['showPrint'] as bool?
       ..token = json['token'] as String
       ..property = json['property']
-      ..message = json['message'] as Map<String, dynamic>?;
+      ..message = json['message'] as Map<String, dynamic>?
+      ..messageJson = json['messageJson'] as String?;
 
 Map<String, dynamic> _$DataSlackSenderToJson(DataSlackSender instance) =>
     <String, dynamic>{
@@ -879,6 +880,7 @@ Map<String, dynamic> _$DataSlackSenderToJson(DataSlackSender instance) =>
       'token': instance.token,
       'property': instance.property,
       'message': instance.message,
+      'messageJson': instance.messageJson,
     };
 
 DataSlackBuild _$DataSlackBuildFromJson(Map<String, dynamic> json) =>
@@ -893,6 +895,7 @@ DataSlackBuild _$DataSlackBuildFromJson(Map<String, dynamic> json) =>
       ..token = json['token'] as String
       ..property = json['property']
       ..message = json['message'] as Map<String, dynamic>?
+      ..messageJson = json['messageJson'] as String?
       ..appName = json['appName'] as String
       ..type = $enumDecode(_$SlackBuildTypeEnumMap, json['type'])
       ..color = json['color'] as String
@@ -910,6 +913,7 @@ Map<String, dynamic> _$DataSlackBuildToJson(DataSlackBuild instance) =>
       'token': instance.token,
       'property': instance.property,
       'message': instance.message,
+      'messageJson': instance.messageJson,
       'appName': instance.appName,
       'type': _$SlackBuildTypeEnumMap[instance.type]!,
       'color': instance.color,
@@ -1606,7 +1610,7 @@ DataStringReplacePattern _$DataStringReplacePatternFromJson(
       ..setResult = json['setResult'] as String?
       ..setExitCode = json['setExitCode'] as String?
       ..showPrint = json['showPrint'] as bool?
-      ..startAt = (json['startAt'] as num).toInt()
+      ..startAt = (json['startAt'] as num?)?.toInt()
       ..startPattern = json['startPattern'] as String
       ..endPattern = json['endPattern'] as String
       ..text = json['text'] as String
@@ -1638,7 +1642,7 @@ DataStringIndex _$DataStringIndexFromJson(Map<String, dynamic> json) =>
       ..setResult = json['setResult'] as String?
       ..setExitCode = json['setExitCode'] as String?
       ..showPrint = json['showPrint'] as bool?
-      ..startAt = (json['startAt'] as num).toInt()
+      ..startAt = (json['startAt'] as num?)?.toInt()
       ..text = json['text'] as String
       ..value = json['value'] as String
       ..setValue = json['setValue'] as String;