diff --git a/OpenUtau.Core/DiffSinger/DiffSingerScript.cs b/OpenUtau.Core/DiffSinger/DiffSingerScript.cs
index 9cd1fa67b..3824b26e2 100644
--- a/OpenUtau.Core/DiffSinger/DiffSingerScript.cs
+++ b/OpenUtau.Core/DiffSinger/DiffSingerScript.cs
@@ -4,7 +4,6 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using Newtonsoft.Json;
 using OpenUtau.Core.Render;
 using OpenUtau.Core.Ustx;
 
@@ -199,7 +198,7 @@ static public void SavePart(UProject project, UVoicePart part, string filePath,
                 .Select(x => new DiffSingerScript(x, options).toRaw())
                 .ToArray();
             File.WriteAllText(filePath,
-                JsonConvert.SerializeObject(ScriptArray, Formatting.Indented),
+                Json.Serialize(ScriptArray),
                 new UTF8Encoding(false));
         }
     }
diff --git a/OpenUtau.Core/DiffSinger/DiffSingerUtils.cs b/OpenUtau.Core/DiffSinger/DiffSingerUtils.cs
index c9f05309c..48a7084dc 100644
--- a/OpenUtau.Core/DiffSinger/DiffSingerUtils.cs
+++ b/OpenUtau.Core/DiffSinger/DiffSingerUtils.cs
@@ -4,7 +4,6 @@
 using System.Linq;
 using System.Text;
 using Microsoft.ML.OnnxRuntime.Tensors;
-using Newtonsoft.Json;
 using OpenUtau.Core.Render;
 
 namespace OpenUtau.Core.DiffSinger {
@@ -319,7 +318,7 @@ public static Dictionary<string, int> LoadPhonemes(string filePath){
 
         static Dictionary<string, int> LoadPhonemesFromJson(string filePath){
             var json = File.ReadAllText(filePath, Encoding.UTF8);
-            return JsonConvert.DeserializeObject<Dictionary<string, int>>(json);
+            return Json.Deserialize<Dictionary<string, int>>(json);
         }
 
         static Dictionary<string, int> LoadPhonemesFromTxt(string filePath){
@@ -333,7 +332,7 @@ static Dictionary<string, int> LoadPhonemesFromTxt(string filePath){
 
         public static Dictionary<string, int> LoadLanguageIds(string filePath){
             var json = File.ReadAllText(filePath, Encoding.UTF8);
-            return JsonConvert.DeserializeObject<Dictionary<string, int>>(json);
+            return Json.Deserialize<Dictionary<string, int>>(json);
         }
 
         public static string PhonemeLanguage(string phoneme){
diff --git a/OpenUtau.Core/Enunu/EnunuClient.cs b/OpenUtau.Core/Enunu/EnunuClient.cs
index e939e0e3a..0cb145dbf 100644
--- a/OpenUtau.Core/Enunu/EnunuClient.cs
+++ b/OpenUtau.Core/Enunu/EnunuClient.cs
@@ -1,7 +1,6 @@
 using System;
 using NetMQ;
 using NetMQ.Sockets;
-using Newtonsoft.Json;
 using Serilog;
 
 namespace OpenUtau.Core.Enunu {
@@ -12,7 +11,7 @@ internal T SendRequest<T>(string[] args) {
         internal T SendRequest<T>(string[] args, string port,int second = 300 ) {
             using (var client = new RequestSocket()) {
                 client.Connect($"tcp://localhost:{port}");
-                string request = JsonConvert.SerializeObject(args);
+                string request = Json.Serialize(args);
                 Log.Information($"EnunuProcess sending {request}");
                 client.SendFrame(request);
                 client.TryReceiveFrameString(TimeSpan.FromSeconds(second), out string? message);
@@ -20,7 +19,7 @@ internal T SendRequest<T>(string[] args, string port,int second = 300 ) {
                 if (string.IsNullOrEmpty(message)) {
                     return (T)Activator.CreateInstance(typeof(T))!;
                 }
-                return JsonConvert.DeserializeObject<T>(message ?? string.Empty)!;
+                return Json.Deserialize<T>(message ?? string.Empty)!;
             }
         }
     }
diff --git a/OpenUtau.Core/Format/Commonnote.cs b/OpenUtau.Core/Format/Commonnote.cs
index 3411562c8..2a2ead933 100644
--- a/OpenUtau.Core/Format/Commonnote.cs
+++ b/OpenUtau.Core/Format/Commonnote.cs
@@ -1,13 +1,8 @@
-using Melanchall.DryWetMidi.Core;
-using Melanchall.DryWetMidi.Interaction;
-using Newtonsoft.Json;
-using OpenUtau.Core.Ustx;
+using OpenUtau.Core.Ustx;
 using OpenUtau.Core.Util;
 using System;
 using System.Collections.Generic;
-using System.ComponentModel.Design;
 using System.Linq;
-using System.Reflection.Emit;
 using TextCopy;
 using Serilog;
 
@@ -62,11 +57,11 @@ public static string Dumps(List<UNote> uNotes, UProject project) {
                 },
                 notes = uNotes.Select(DumpNote).ToList(),
             };
-            return JsonConvert.SerializeObject(data);
+            return Json.Serialize(data);
         }
 
         public static List<UNote> Loads(string text, UProject project) {
-            var data = JsonConvert.DeserializeObject<CommonnoteData>(text);
+            var data = Json.Deserialize<CommonnoteData>(text);
             if (data.identifier != "commonnote") {
                 Log.Error($"Clipboard is missing commonnote header");
                 return null;
diff --git a/OpenUtau.Core/Format/Ufdata.cs b/OpenUtau.Core/Format/Ufdata.cs
index e31c23c3b..6593863f0 100644
--- a/OpenUtau.Core/Format/Ufdata.cs
+++ b/OpenUtau.Core/Format/Ufdata.cs
@@ -1,8 +1,6 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using Newtonsoft.Json;
-
 using OpenUtau.Core.Ustx;
 
 //reference: https://github.com/sdercolin/utaformatix-data/blob/main/lib/csharp/UtaFormatix.Data
@@ -118,7 +116,7 @@ public static UProject Load(string file){
             Ustx.AddDefaultExpressions(project);
             project.FilePath = file;
 
-            var ufProject = JsonConvert.DeserializeObject<UfFile>(File.ReadAllText(file,Encoding.UTF8)).project;
+            var ufProject = Json.Deserialize<UfFile>(File.ReadAllText(file,Encoding.UTF8)).project;
             
             //parse tempo
             project.tempos=ufProject.tempos
diff --git a/OpenUtau.Core/OpenUtau.Core.csproj b/OpenUtau.Core/OpenUtau.Core.csproj
index de3d0761f..517530d20 100644
--- a/OpenUtau.Core/OpenUtau.Core.csproj
+++ b/OpenUtau.Core/OpenUtau.Core.csproj
@@ -18,7 +18,6 @@
     <PackageReference Include="NAudio.Core" Version="2.2.1" />
     <PackageReference Include="NAudio.Vorbis" Version="1.5.0" />
     <PackageReference Include="NeoLua" Version="1.3.19" />
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="NLayer.NAudioSupport" Version="1.4.0" />
     <PackageReference Include="NumSharp" Version="0.30.0" />
     <PackageReference Include="NWaves" Version="0.9.6" />
diff --git a/OpenUtau.Core/PackageManager.cs b/OpenUtau.Core/PackageManager.cs
index c49074be3..6765fec7d 100644
--- a/OpenUtau.Core/PackageManager.cs
+++ b/OpenUtau.Core/PackageManager.cs
@@ -5,9 +5,9 @@
 using System.Net.Http;
 using System.Security.Cryptography;
 using System.Text;
+using System.Text.Json;
+using System.Text.Json.Nodes;
 using System.Threading.Tasks;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
 using Serilog;
 using SharpCompress.Archives;
 using OpenUtau.Core.Util;
@@ -63,10 +63,10 @@ public async Task<List<RegistrySoftware>> FetchRegistryAsync() {
 
             List<RegistrySoftware> list = new List<RegistrySoftware>();
             try {
-                var token = JToken.Parse(body);
-                var items = token["items"];
-                if (items != null && items.Type == JTokenType.Array) {
-                    list = items.ToObject<List<RegistrySoftware>>() ?? new List<RegistrySoftware>();
+                var token = JsonObject.Parse(body);
+                var items = token?["items"];
+                if (items?.GetValueKind() == JsonValueKind.Array) {
+                    list = Json.Deserialize<List<RegistrySoftware>>(items) ?? new List<RegistrySoftware>();
                 }
             } catch (Exception e) {
                 Log.Warning(e, "Failed to parse registry JSON");
diff --git a/OpenUtau.Core/Util/Json.cs b/OpenUtau.Core/Util/Json.cs
new file mode 100644
index 000000000..cbf7d4b39
--- /dev/null
+++ b/OpenUtau.Core/Util/Json.cs
@@ -0,0 +1,32 @@
+using System.IO;
+using System.Text.Encodings.Web;
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+namespace OpenUtau.Core {
+    public class Json {
+
+        public static readonly JsonSerializerOptions DefaultJsonOptions = new() {
+            Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
+            IncludeFields = true,
+            WriteIndented = true
+        };
+
+        public static string Serialize(object? graph, JsonSerializerOptions? options = null) {
+            return JsonSerializer.Serialize(graph, options ?? DefaultJsonOptions);
+        }
+
+        public static T? Deserialize<T>(string input, JsonSerializerOptions? options = null) {
+            return JsonSerializer.Deserialize<T>(input, options ?? DefaultJsonOptions);
+        }
+
+        public static T? Deserialize<T>(Stream input, JsonSerializerOptions? options = null) {
+            return JsonSerializer.Deserialize<T>(input, options ?? DefaultJsonOptions);
+        }
+
+        public static T? Deserialize<T>(JsonNode? input, JsonSerializerOptions? options = null) {
+            return input.Deserialize<T>(options ?? DefaultJsonOptions);
+        }
+
+    }
+}
\ No newline at end of file
diff --git a/OpenUtau.Core/Util/NotePresets.cs b/OpenUtau.Core/Util/NotePresets.cs
index ddf3c73b8..6125c12f0 100644
--- a/OpenUtau.Core/Util/NotePresets.cs
+++ b/OpenUtau.Core/Util/NotePresets.cs
@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
-using Newtonsoft.Json;
 using OpenUtau.Core.Ustx;
 using Serilog;
 
@@ -17,7 +16,7 @@ static NotePresets() {
         public static void Save() {
             try {
                 File.WriteAllText(PathManager.Inst.NotePresetsFilePath,
-                    JsonConvert.SerializeObject(Default, Formatting.Indented),
+                    Json.Serialize(Default),
                     Encoding.UTF8);
             } catch (Exception e) {
                 Log.Error(e, "Failed to save note presets.");
@@ -27,7 +26,7 @@ public static void Save() {
         private static void Load() {
             try {
                 if (File.Exists(PathManager.Inst.NotePresetsFilePath)) {
-                    Default = JsonConvert.DeserializeObject<SerializableNotePresets>(
+                    Default = Json.Deserialize<SerializableNotePresets>(
                         File.ReadAllText(PathManager.Inst.NotePresetsFilePath, Encoding.UTF8));
                 } else {
                     Reset();
diff --git a/OpenUtau.Core/Util/Preferences.cs b/OpenUtau.Core/Util/Preferences.cs
index 132412639..d5f20b326 100644
--- a/OpenUtau.Core/Util/Preferences.cs
+++ b/OpenUtau.Core/Util/Preferences.cs
@@ -4,14 +4,14 @@
 using System.Globalization;
 using System.IO;
 using System.Text;
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 using OpenUtau.Core.Render;
 using Serilog;
 
 namespace OpenUtau.Core.Util {
 
     public static class Preferences {
-        public static SerializablePreferences Default;
+        public static SerializablePreferences Default { get; private set; }
 
         static Preferences() {
             Load();
@@ -20,7 +20,7 @@ static Preferences() {
         public static void Save() {
             try {
                 File.WriteAllText(PathManager.Inst.PrefsFilePath,
-                    JsonConvert.SerializeObject(Default, Formatting.Indented),
+                    Json.Serialize(Default),
                     Encoding.UTF8);
             } catch (Exception e) {
                 Log.Error(e, "Failed to save prefs.");
@@ -34,7 +34,7 @@ public static void Reset() {
                 string exePath = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName);
                 string shippedPrefsPath = Path.Combine(exePath, "prefs-default.json");
                 if (File.Exists(shippedPrefsPath)) {
-                    var shippedPrefs = JsonConvert.DeserializeObject<SerializablePreferences>(
+                    var shippedPrefs = Json.Deserialize<SerializablePreferences>(
                         File.ReadAllText(shippedPrefsPath, Encoding.UTF8));
                     if (shippedPrefs != null) {
                         Default = shippedPrefs;
@@ -102,7 +102,7 @@ private static void AddRecentFile(string filePath) {
         private static void Load() {
             try {
                 if (File.Exists(PathManager.Inst.PrefsFilePath)) {
-                    Default = JsonConvert.DeserializeObject<SerializablePreferences>(
+                    Default = Json.Deserialize<SerializablePreferences>(
                         File.ReadAllText(PathManager.Inst.PrefsFilePath, Encoding.UTF8));
                     if(Default == null) {
                         Reset();
@@ -217,43 +217,44 @@ public class SerializablePreferences {
             public bool LockUnselectedNotesVibrato = true;
             public bool LockUnselectedNotesExpressions = true;
             public bool VoicebankPublishUseIgnore = true;
-            public string VoicebankPublishIgnores = @"#Adobe Audition
-*.pkf
+            public string VoicebankPublishIgnores = """
+                #Adobe Audition
+                *.pkf
 
-#UTAU Engines
-*.ctspec
-*.d4c
-*.dio
-*.frc
-*.frt
-#*.frq
-*.harvest
-*.lessaudio
-*.llsm
-*.mrq
-*.pitchtier
-*.pkf
-*.platinum
-*.pmk
-*.sc.npz
-*.star
-*.uspec
-*.vs4ufrq
+                #UTAU Engines
+                *.ctspec
+                *.d4c
+                *.dio
+                *.frc
+                *.frt
+                #*.frq
+                *.harvest
+                *.lessaudio
+                *.llsm
+                *.mrq
+                *.pitchtier
+                *.pkf
+                *.platinum
+                *.pmk
+                *.sc.npz
+                *.star
+                *.uspec
+                *.vs4ufrq
 
-#UTAU related tools
-\$read
-*.setParam-Scache
-*.lbp
-*.lbp.caches/*
+                #UTAU related tools
+                \$read
+                *.setParam-Scache
+                *.lbp
+                *.lbp.caches/*
 
-#OpenUtau
-errors.txt
-";
+                #OpenUtau
+                errors.txt
+                """;
             public string RecoveryPath = string.Empty;
             public bool DetachPianoRoll = false;
 
             // Legacy
-            [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
+            [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
             public int? Theme;
         }
     }
diff --git a/OpenUtau.Core/Vogen/VogenSingerLoader.cs b/OpenUtau.Core/Vogen/VogenSingerLoader.cs
index 252325603..9c6f2b73c 100644
--- a/OpenUtau.Core/Vogen/VogenSingerLoader.cs
+++ b/OpenUtau.Core/Vogen/VogenSingerLoader.cs
@@ -2,8 +2,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Text;
-using Newtonsoft.Json;
 using OpenUtau.Core.Ustx;
 using OpenUtau.Core.Util;
 using Serilog;
@@ -76,9 +74,7 @@ public USinger LoadSinger(string filePath) {
                     throw new ArgumentException("missing meta.json");
                 }
                 using (var stream = metaEntry.OpenEntryStream()) {
-                    using var reader = new StreamReader(stream, Encoding.UTF8);
-                    JsonSerializer serializer = new JsonSerializer();
-                    meta = (VogenMeta)serializer.Deserialize(reader, typeof(VogenMeta));
+                    meta = Json.Deserialize<VogenMeta>(stream);
                 }
                 model = Zip.ExtractBytes(archive, "model.onnx");
                 if (model == null) {
diff --git a/OpenUtau.Core/Voicevox/VoicevoxConfig.cs b/OpenUtau.Core/Voicevox/VoicevoxConfig.cs
index 7791b2820..285826ca8 100644
--- a/OpenUtau.Core/Voicevox/VoicevoxConfig.cs
+++ b/OpenUtau.Core/Voicevox/VoicevoxConfig.cs
@@ -3,7 +3,7 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using Newtonsoft.Json.Linq;
+using System.Text.Json.Nodes;
 using OpenUtau.Classic;
 using OpenUtau.Core.Ustx;
 using OpenUtau.Core.Util;
@@ -34,13 +34,13 @@ public class VoicevoxConfig {
         public static VoicevoxConfig Load(USinger singer) {
             try {
                 var response = VoicevoxClient.Inst.SendRequest(new VoicevoxURL() { method = "GET", path = "/engine_manifest" });
-                var jObj = JObject.Parse(response.Item1);
-                if (jObj.ContainsKey("detail")) {
+                var jObj = JsonObject.Parse(response.Item1);
+                if (jObj?.AsObject().ContainsKey("detail") == true) {
                     var errorMessage = $"Response was incorrect. : {jObj}";
                     Log.Error(errorMessage);
                     throw new VoicevoxException(errorMessage);
                 }
-                var manifest = jObj.ToObject<Engine_manifest>();
+                var manifest = Json.Deserialize<Engine_manifest>(jObj);
                 manifest.SaveLicenses(singer.Location);
             } catch (Exception e) {
                 var errorMessage = $"Could not load Licenses.:{e}";
@@ -50,13 +50,13 @@ public static VoicevoxConfig Load(USinger singer) {
             try {
 
                 var response = VoicevoxClient.Inst.SendRequest(new VoicevoxURL() { method = "GET", path = "/singers" });
-                var jObj = JObject.Parse(response.Item1);
-                if (jObj.ContainsKey("detail")) {
+                var jObj = JsonObject.Parse(response.Item1);
+                if (jObj?.AsObject().ContainsKey("detail") == true) {
                     var errorMessage = $"Response was incorrect. : {jObj}";
                     Log.Error(errorMessage);
                     throw new VoicevoxException(errorMessage);
                 }
-                var configs = jObj["json"].ToObject<List<RawVoicevoxConfig>>();
+                var configs = Json.Deserialize<List<RawVoicevoxConfig>>(jObj?["json"]);
                 var parentDirectory = Directory.GetParent(singer.Location).ToString();
                 List<VoicevoxConfig> vvList = new List<VoicevoxConfig>();
                 foreach (RawVoicevoxConfig rowVoicevoxConfig in configs) {
@@ -95,11 +95,11 @@ public void LoadInfo(VoicevoxConfig voicevoxConfig, string location) {
             if (voicevoxConfig.style_infos == null) {
                 var queryurl = new VoicevoxURL() { method = "GET", path = "/singer_info", query = new Dictionary<string, string> { { "speaker_uuid", voicevoxConfig.speaker_uuid } } };
                 var response = VoicevoxClient.Inst.SendRequest(queryurl);
-                var jObj = JObject.Parse(response.Item1);
-                if (jObj.ContainsKey("detail")) {
+                var jObj = JsonObject.Parse(response.Item1);
+                if (jObj?.AsObject().ContainsKey("detail") == true) {
                     Log.Error($"Response was incorrect. : {jObj}");
                 } else {
-                    var rawSinger_Info = jObj.ToObject<RawSinger_info>();
+                    var rawSinger_Info = Json.Deserialize<RawSinger_info>(jObj);
                     if (rawSinger_Info != null) {
                         rawSinger_Info.SetInfo(voicevoxConfig, location);
                     }
diff --git a/OpenUtau.Core/Voicevox/VoicevoxRenderer.cs b/OpenUtau.Core/Voicevox/VoicevoxRenderer.cs
index 3f78878f7..3ea86560e 100644
--- a/OpenUtau.Core/Voicevox/VoicevoxRenderer.cs
+++ b/OpenUtau.Core/Voicevox/VoicevoxRenderer.cs
@@ -2,11 +2,10 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Text.Json.Nodes;
 using System.Threading;
 using System.Threading.Tasks;
 using NAudio.Wave;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
 using OpenUtau.Core.Format;
 using OpenUtau.Core.Render;
 using OpenUtau.Core.Ustx;
@@ -117,14 +116,14 @@ public Task<RenderResult> Render(RenderPhrase phrase, Progress progress, int tra
                                         speaker = style.id;
                                     }
                                 });
-                                var queryurl = new VoicevoxURL() { method = "POST", path = "/frame_synthesis", query = new Dictionary<string, string> { { "speaker", speaker.ToString() } }, body = JsonConvert.SerializeObject(vsParams), accept = "audio/wav" };
+                                var queryurl = new VoicevoxURL() { method = "POST", path = "/frame_synthesis", query = new Dictionary<string, string> { { "speaker", speaker.ToString() } }, body = Json.Serialize(vsParams), accept = "audio/wav" };
                                 var response = VoicevoxClient.Inst.SendRequest(queryurl);
                                 byte[] bytes = null;
                                 if (!response.Item2.Equals(null)) {
                                     bytes = response.Item2;
                                 } else if (!string.IsNullOrEmpty(response.Item1)) {
-                                    var jObj = JObject.Parse(response.Item1);
-                                    if (jObj.ContainsKey("detail")) {
+                                    var jObj = JsonObject.Parse(response.Item1);
+                                    if (jObj?.AsObject().ContainsKey("detail") == true) {
                                         Log.Error($"Voice synthesis failed with the VOICEVOX engine. : {jObj}");
                                     }
                                 }
diff --git a/OpenUtau.Core/Voicevox/VoicevoxUtils.cs b/OpenUtau.Core/Voicevox/VoicevoxUtils.cs
index bcd57443e..16bbf63bb 100644
--- a/OpenUtau.Core/Voicevox/VoicevoxUtils.cs
+++ b/OpenUtau.Core/Voicevox/VoicevoxUtils.cs
@@ -2,8 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
+using System.Text.Json.Nodes;
 using OpenUtau.Core.Render;
 using Serilog;
 
@@ -181,15 +180,13 @@ public static class VoicevoxUtils {
         public static Phoneme_list phoneme_List = new Phoneme_list();
 
         public static VoicevoxSynthParams VoicevoxVoiceBase(VoicevoxQueryMain qNotes, string id) {
-            var queryurl = new VoicevoxURL() { method = "POST", path = "/sing_frame_audio_query", query = new Dictionary<string, string> { { "speaker", id } }, body = JsonConvert.SerializeObject(qNotes) };
+            var queryurl = new VoicevoxURL() { method = "POST", path = "/sing_frame_audio_query", query = new Dictionary<string, string> { { "speaker", id } }, body = Json.Serialize(qNotes) };
             var response = VoicevoxClient.Inst.SendRequest(queryurl);
-            VoicevoxSynthParams vvNotes;
-            var jObj = JObject.Parse(response.Item1);
-            if (jObj.ContainsKey("detail")) {
-                Log.Error($"Response was incorrect. : {jObj}");
+            var jObj = JsonObject.Parse(response.Item1);
+            if (jObj?.AsObject().ContainsKey("detail") == true) {
+                Log.Error($"Response was incorrect. : {jObj["detail"]}");
             } else {
-                vvNotes = jObj.ToObject<VoicevoxSynthParams>();
-                return vvNotes;
+                return Json.Deserialize<VoicevoxSynthParams>(jObj);
             }
             return new VoicevoxSynthParams();
         }
@@ -254,28 +251,28 @@ public static VoicevoxQueryMain NoteGroupsToVQuery(VoicevoxNote[] vNotes, TimeAx
 
         public static List<double> QueryToF0(VoicevoxQueryMain vqMain, VoicevoxSynthParams vsParams, string id) {
             VoicevoxQueryParams vqParams = new VoicevoxQueryParams() { score = vqMain, frame_audio_query = vsParams }; 
-            var queryurl = new VoicevoxURL() { method = "POST", path = "/sing_frame_f0", query = new Dictionary<string, string> { { "speaker", id } }, body = JsonConvert.SerializeObject(vqParams) };
+            var queryurl = new VoicevoxURL() { method = "POST", path = "/sing_frame_f0", query = new Dictionary<string, string> { { "speaker", id } }, body = Json.Serialize(vqParams) };
             var response = VoicevoxClient.Inst.SendRequest(queryurl);
             List<double> f0s = new List<double>();
-            var jObj = JObject.Parse(response.Item1);
-            if (jObj.ContainsKey("detail")) {
-                Log.Error($"Response was incorrect. : {jObj}");
+            var jObj = JsonObject.Parse(response.Item1);
+            if (jObj?.AsObject().ContainsKey("detail") == true) {
+                Log.Error($"Response was incorrect. : {jObj["detail"]}");
             } else {
-                f0s = jObj["json"].ToObject<List<double>>();
+                f0s = Json.Deserialize<List<double>>(jObj?["json"]);
             }
             return f0s;
         }
 
         public static List<double> QueryToVolume(VoicevoxQueryMain vqMain, VoicevoxSynthParams vsParams, string id) {
             VoicevoxQueryParams vqParams = new VoicevoxQueryParams() { score = vqMain, frame_audio_query = vsParams };
-            var queryurl = new VoicevoxURL() { method = "POST", path = "/sing_frame_volume", query = new Dictionary<string, string> { { "speaker", id } }, body = JsonConvert.SerializeObject(vqParams) };
+            var queryurl = new VoicevoxURL() { method = "POST", path = "/sing_frame_volume", query = new Dictionary<string, string> { { "speaker", id } }, body = Json.Serialize(vqParams) };
             var response = VoicevoxClient.Inst.SendRequest(queryurl);
             List<double> volumes = new List<double>();
-            var jObj = JObject.Parse(response.Item1);
-            if (jObj.ContainsKey("detail")) {
-                Log.Error($"Response was incorrect. : {jObj}");
+            var jObj = JsonObject.Parse(response.Item1);
+            if (jObj?.AsObject().ContainsKey("detail") == true) {
+                Log.Error($"Response was incorrect. : {jObj["detail"]}");
             } else {
-                volumes = jObj["json"].ToObject<List<double>>();
+                volumes = Json.Deserialize<List<double>>(jObj?["json"]);
             }
             return volumes;
         }
diff --git a/OpenUtau.Plugin.Builtin/EnunuOnnx/Scaler.cs b/OpenUtau.Plugin.Builtin/EnunuOnnx/Scaler.cs
index 6201fcfe5..a9dcbc5e4 100644
--- a/OpenUtau.Plugin.Builtin/EnunuOnnx/Scaler.cs
+++ b/OpenUtau.Plugin.Builtin/EnunuOnnx/Scaler.cs
@@ -2,7 +2,7 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using Newtonsoft.Json;
+using OpenUtau.Core;
 
 namespace OpenUtau.Plugin.Builtin.EnunuOnnx {
     public class ScalerLine {
@@ -24,7 +24,7 @@ public static Scaler load(string path,Encoding encoding = null) {
             if (encoding == null) {
                 encoding = Encoding.UTF8;
             }
-            return JsonConvert.DeserializeObject<Scaler>(
+            return Json.Deserialize<Scaler>(
                 File.ReadAllText(path, encoding));
         }
 
diff --git a/OpenUtau.Test/OpenUtau.Test.csproj b/OpenUtau.Test/OpenUtau.Test.csproj
index d57c9d991..b0a83cafd 100644
--- a/OpenUtau.Test/OpenUtau.Test.csproj
+++ b/OpenUtau.Test/OpenUtau.Test.csproj
@@ -13,7 +13,6 @@
   <ItemGroup>
     <PackageReference Include="Avalonia.Headless.XUnit" Version="11.2.4" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.2" />
     <PackageReference Include="System.Text.Json" Version="9.0.2" />
     <PackageReference Include="xunit" Version="2.9.2" />
diff --git a/OpenUtau/Integrations/VLabelerClient.cs b/OpenUtau/Integrations/VLabelerClient.cs
index 2a4525ff4..b105412f2 100644
--- a/OpenUtau/Integrations/VLabelerClient.cs
+++ b/OpenUtau/Integrations/VLabelerClient.cs
@@ -8,7 +8,6 @@
 using K4os.Hash.xxHash;
 using NetMQ;
 using NetMQ.Sockets;
-using Newtonsoft.Json;
 using OpenUtau.Core;
 using Serilog;
 
@@ -86,7 +85,7 @@ private static string HashHex(string s) {
         private bool Heartbeat() {
             using (var client = new RequestSocket()) {
                 client.Connect("tcp://localhost:32342");
-                string reqStr = JsonConvert.SerializeObject(new HeartbeatRequest());
+                string reqStr = Json.Serialize(new HeartbeatRequest());
                 client.SendFrame(reqStr);
                 if (client.TryReceiveFrameString(TimeSpan.FromMilliseconds(1000), out string? respStr)) {
                     return true;
@@ -116,7 +115,7 @@ private void OpenOrCreate(Core.Ustx.USinger singer, Core.Ustx.UOto? oto) {
             }
             using (var client = new RequestSocket()) {
                 client.Connect("tcp://localhost:32342");
-                string reqStr = JsonConvert.SerializeObject(request);
+                string reqStr = Json.Serialize(request);
                 client.SendFrame(reqStr);
                 if (!client.TryReceiveFrameString(TimeSpan.FromMilliseconds(1000), out string? respStr)) {
                     Log.Warning($"Failed to OpenOrCreate with vLabeler");
diff --git a/OpenUtau/ViewModels/UpdaterViewModel.cs b/OpenUtau/ViewModels/UpdaterViewModel.cs
index ff24dedd2..3549a6037 100644
--- a/OpenUtau/ViewModels/UpdaterViewModel.cs
+++ b/OpenUtau/ViewModels/UpdaterViewModel.cs
@@ -10,7 +10,6 @@
 using NetSparkleUpdater.Enums;
 using NetSparkleUpdater.Interfaces;
 using NetSparkleUpdater.SignatureVerifiers;
-using Newtonsoft.Json;
 using OpenUtau.Core;
 using OpenUtau.Core.Util;
 using ReactiveUI.Fody.Helpers;
@@ -87,7 +86,7 @@ public UpdaterViewModel() {
             using var resposne = await client.GetAsync("https://api.github.com/repos/stakira/OpenUtau/releases");
             resposne.EnsureSuccessStatusCode();
             string respBody = await resposne.Content.ReadAsStringAsync();
-            List<GithubRelease>? releases = JsonConvert.DeserializeObject<List<GithubRelease>>(respBody);
+            var releases = Json.Deserialize<List<GithubRelease>>(respBody);
             if (releases == null) {
                 return null;
             }