diff --git a/src/Squidex.Domain.Apps.Core.Model/Apps/Json/JsonLanguagesConfig.cs b/src/Squidex.Domain.Apps.Core.Model/Apps/Json/JsonLanguagesConfig.cs
new file mode 100644
index 000000000..8ec216f76
--- /dev/null
+++ b/src/Squidex.Domain.Apps.Core.Model/Apps/Json/JsonLanguagesConfig.cs
@@ -0,0 +1,63 @@
+// ==========================================================================
+//  JsonLanguagesConfig.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+using System.Collections.Generic;
+using Newtonsoft.Json;
+using Squidex.Infrastructure;
+
+namespace Squidex.Domain.Apps.Core.Apps.Json
+{
+    public sealed class JsonLanguagesConfig
+    {
+        [JsonProperty]
+        public Dictionary<string, JsonLanguageConfig> Languages { get; set; }
+
+        [JsonProperty]
+        public Language Master { get; set; }
+
+        public JsonLanguagesConfig()
+        {
+        }
+
+        public JsonLanguagesConfig(LanguagesConfig value)
+        {
+            Languages = new Dictionary<string, JsonLanguageConfig>(value.Count);
+
+            foreach (LanguageConfig config in value)
+            {
+                Languages.Add(config.Language, new JsonLanguageConfig(config));
+            }
+
+            Master = value.Master?.Language;
+        }
+
+        public LanguagesConfig ToConfig()
+        {
+            var languagesConfig = new LanguageConfig[Languages?.Count ?? 0];
+
+            if (Languages != null)
+            {
+                var i = 0;
+
+                foreach (var config in Languages)
+                {
+                    languagesConfig[i++] = config.Value.ToConfig(config.Key);
+                }
+            }
+
+            var result = LanguagesConfig.Build(languagesConfig);
+
+            if (Master != null)
+            {
+                result = result.MakeMaster(Master);
+            }
+
+            return result;
+        }
+    }
+}
diff --git a/src/Squidex.Domain.Apps.Core.Model/Apps/Json/LanguagesConfigConverter.cs b/src/Squidex.Domain.Apps.Core.Model/Apps/Json/LanguagesConfigConverter.cs
index 1ae94f71c..d720dfca8 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Apps/Json/LanguagesConfigConverter.cs
+++ b/src/Squidex.Domain.Apps.Core.Model/Apps/Json/LanguagesConfigConverter.cs
@@ -7,7 +7,6 @@
 // ==========================================================================
 
 using System;
-using System.Collections.Generic;
 using Newtonsoft.Json;
 using Squidex.Infrastructure.Json;
 
@@ -17,30 +16,16 @@ namespace Squidex.Domain.Apps.Core.Apps.Json
     {
         protected override void WriteValue(JsonWriter writer, LanguagesConfig value, JsonSerializer serializer)
         {
-            var json = new Dictionary<string, JsonLanguageConfig>(value.Count);
-
-            foreach (LanguageConfig config in value)
-            {
-                json.Add(config.Language, new JsonLanguageConfig(config));
-            }
+            var json = new JsonLanguagesConfig(value);
 
             serializer.Serialize(writer, json);
         }
 
         protected override LanguagesConfig ReadValue(JsonReader reader, Type objectType, JsonSerializer serializer)
         {
-            var json = serializer.Deserialize<Dictionary<string, JsonLanguageConfig>>(reader);
-
-            var languagesConfig = new LanguageConfig[json.Count];
-
-            var i = 0;
-
-            foreach (var config in json)
-            {
-                languagesConfig[i++] = config.Value.ToConfig(config.Key);
-            }
+            var json = serializer.Deserialize<JsonLanguagesConfig>(reader);
 
-            return LanguagesConfig.Build(languagesConfig);
+            return json.ToConfig();
         }
     }
 }
diff --git a/tests/Squidex.Domain.Apps.Core.Tests/Model/Apps/LanguagesConfigJsonTests.cs b/tests/Squidex.Domain.Apps.Core.Tests/Model/Apps/LanguagesConfigJsonTests.cs
index cd5ae5eb9..51012e4dd 100644
--- a/tests/Squidex.Domain.Apps.Core.Tests/Model/Apps/LanguagesConfigJsonTests.cs
+++ b/tests/Squidex.Domain.Apps.Core.Tests/Model/Apps/LanguagesConfigJsonTests.cs
@@ -6,6 +6,7 @@
 //  All rights reserved.
 // ==========================================================================
 
+using System.Linq;
 using FluentAssertions;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
@@ -25,11 +26,14 @@ namespace Squidex.Domain.Apps.Core.Model.Apps
             var sut = LanguagesConfig.Build(
                 new LanguageConfig(Language.EN),
                 new LanguageConfig(Language.DE, true, Language.EN),
-                new LanguageConfig(Language.IT, false, Language.DE));
+                new LanguageConfig(Language.IT, false, Language.DE))
+                .MakeMaster(Language.IT);
 
             var serialized = JToken.FromObject(sut, serializer).ToObject<LanguagesConfig>(serializer);
 
             serialized.ShouldBeEquivalentTo(sut);
+
+            Assert.Same(serialized.FirstOrDefault(x => x.Key == "it"), serialized.Master);
         }
     }
 }