diff --git a/Scripts/LLM/ChatGPT/ChatGPTService.cs b/Scripts/LLM/ChatGPT/ChatGPTService.cs
index 851761a..0613e4a 100644
--- a/Scripts/LLM/ChatGPT/ChatGPTService.cs
+++ b/Scripts/LLM/ChatGPT/ChatGPTService.cs
@@ -13,6 +13,8 @@ namespace ChatdollKit.LLM.ChatGPT
     public class ChatGPTService : LLMServiceBase
     {
         public string HistoryKey = "ChatGPTHistories";
+        public string CustomParameterKey = "ChatGPTParameters";
+        public string CustomHeaderKey = "ChatGPTHeaders";
 
         [Header("API configuration")]
         public string ApiKey;
@@ -21,6 +23,11 @@ public class ChatGPTService : LLMServiceBase
         public bool IsAzure;
         public int MaxTokens = 0;
         public float Temperature = 0.5f;
+        public float FrequencyPenalty = 0.0f;
+        public bool Logprobs = false;  // Not available on gpt-4v
+        public int TopLogprobs = 0;    // Set true to Logprobs to use TopLogprobs
+        public float PresencePenalty = 0.0f;
+        public List<string> Stop;
 
         [Header("Network configuration")]
         [SerializeField]
@@ -120,11 +127,18 @@ public override async UniTask<List<ILLMMessage>> MakePromptAsync(string userId,
 
         public override async UniTask<ILLMSession> GenerateContentAsync(List<ILLMMessage> messages, Dictionary<string, object> payloads, bool useFunctions = true, int retryCounter = 1, CancellationToken token = default)
         {
+            // Custom parameters and headers
+            var stateData = (Dictionary<string, object>)payloads["StateData"];
+            var customParameters = stateData.ContainsKey(CustomParameterKey) ? (Dictionary<string, string>)stateData[CustomParameterKey] : new Dictionary<string, string>();
+            var customHeaders = stateData.ContainsKey(CustomHeaderKey) ? (Dictionary<string, string>)stateData[CustomHeaderKey] : new Dictionary<string, string>();
+
+            // Start streaming session
             var chatGPTSession = new ChatGPTSession();
             chatGPTSession.Contexts = messages;
-            chatGPTSession.StreamingTask = StartStreamingAsync(chatGPTSession, useFunctions, token);
+            chatGPTSession.StreamingTask = StartStreamingAsync(chatGPTSession, customParameters, customHeaders, useFunctions, token);
             chatGPTSession.FunctionName = await WaitForFunctionName(chatGPTSession, token);
 
+            // Retry
             if (chatGPTSession.ResponseType == ResponseType.Timeout)
             {
                 if (retryCounter > 0)
@@ -143,7 +157,7 @@ public override async UniTask<ILLMSession> GenerateContentAsync(List<ILLMMessage
             return chatGPTSession;
         }
 
-        public virtual async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession, bool useFunctions = true, CancellationToken token = default)
+        public virtual async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession, Dictionary<string, string> customParameters, Dictionary<string, string> customHeaders, bool useFunctions = true, CancellationToken token = default)
         {
             // Make request data
             var data = new Dictionary<string, object>()
@@ -151,8 +165,11 @@ public virtual async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession,
                 { "model", Model },
                 { "temperature", Temperature },
                 { "messages", chatGPTSession.Contexts },
+                { "frequency_penalty", FrequencyPenalty },
+                { "presence_penalty", PresencePenalty },
                 { "stream", true },
             };
+
             if (MaxTokens > 0)
             {
                 data.Add("max_tokens", MaxTokens);
@@ -161,6 +178,19 @@ public virtual async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession,
             {
                 data.Add("functions", llmTools);
             }
+            if (Logprobs == true)
+            {
+                data.Add("logprobs", true);
+                data.Add("top_logprobs", TopLogprobs);
+            }
+            if (Stop != null && Stop.Count > 0)
+            {
+                data.Add("stop", Stop);
+            }
+            foreach (var p in customParameters)
+            {
+                data[p.Key] = p.Value;
+            }
 
             // Prepare API request
             using var streamRequest = new UnityWebRequest(
@@ -178,6 +208,11 @@ public virtual async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession,
                 streamRequest.SetRequestHeader("Authorization", "Bearer " + ApiKey);
             }
             streamRequest.SetRequestHeader("Content-Type", "application/json");
+            foreach (var h in customHeaders)
+            {
+                streamRequest.SetRequestHeader(h.Key, h.Value);
+            }
+
             if (DebugMode)
             {
                 Debug.Log($"Request to ChatGPT: {JsonConvert.SerializeObject(data)}");
diff --git a/Scripts/LLM/ChatGPT/ChatGPTServiceWebGL.cs b/Scripts/LLM/ChatGPT/ChatGPTServiceWebGL.cs
index a79fa1c..6810a65 100644
--- a/Scripts/LLM/ChatGPT/ChatGPTServiceWebGL.cs
+++ b/Scripts/LLM/ChatGPT/ChatGPTServiceWebGL.cs
@@ -30,7 +30,7 @@ public override bool IsEnabled
         protected bool isChatCompletionJSDone { get; set; } = false;
         protected Dictionary<string, ChatGPTSession> sessions { get; set; } = new Dictionary<string, ChatGPTSession>();
 
-        public override async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession, bool useFunctions = true, CancellationToken token = default)
+        public override async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession, Dictionary<string, string> customParameters, Dictionary<string, string> customHeaders, bool useFunctions = true, CancellationToken token = default)
         {
             // Add session for callback
             var sessionId = Guid.NewGuid().ToString();
@@ -42,6 +42,8 @@ public override async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession,
                 { "model", Model },
                 { "temperature", Temperature },
                 { "messages", chatGPTSession.Contexts },
+                { "frequency_penalty", FrequencyPenalty },
+                { "presence_penalty", PresencePenalty },
                 { "stream", true },
             };
             if (MaxTokens > 0)
@@ -52,6 +54,25 @@ public override async UniTask StartStreamingAsync(ChatGPTSession chatGPTSession,
             {
                 data.Add("functions", llmTools);
             }
+            if (Logprobs == true)
+            {
+                data.Add("logprobs", true);
+                data.Add("top_logprobs", TopLogprobs);
+            }
+            if (Stop != null && Stop.Count > 0)
+            {
+                data.Add("stop", Stop);
+            }
+            foreach (var p in customParameters)
+            {
+                data[p.Key] = p.Value;
+            }
+
+            // TODO: Support custom headers later...
+            if (customHeaders.Count >= 0)
+            {
+                Debug.LogWarning("Custom headers for ChatGPT on WebGL is not supported for now.");
+            }
 
             // Start API stream
             isChatCompletionJSDone = false;
diff --git a/Scripts/LLM/Claude/ClaudeService.cs b/Scripts/LLM/Claude/ClaudeService.cs
index ae35ebe..f9be764 100644
--- a/Scripts/LLM/Claude/ClaudeService.cs
+++ b/Scripts/LLM/Claude/ClaudeService.cs
@@ -13,6 +13,8 @@ namespace ChatdollKit.LLM.Claude
     public class ClaudeService : LLMServiceBase
     {
         public string HistoryKey = "ClaudeHistories";
+        public string CustomParameterKey = "ClaudeParameters";
+        public string CustomHeaderKey = "ClaudeHeaders";
 
         [Header("API configuration")]
         public string ApiKey;
@@ -81,11 +83,18 @@ public override async UniTask<List<ILLMMessage>> MakePromptAsync(string userId,
 
         public override async UniTask<ILLMSession> GenerateContentAsync(List<ILLMMessage> messages, Dictionary<string, object> payloads, bool useFunctions = true, int retryCounter = 1, CancellationToken token = default)
         {
+            // Custom parameters and headers
+            var stateData = (Dictionary<string, object>)payloads["StateData"];
+            var customParameters = stateData.ContainsKey(CustomParameterKey) ? (Dictionary<string, string>)stateData[CustomParameterKey] : new Dictionary<string, string>();
+            var customHeaders = stateData.ContainsKey(CustomHeaderKey) ? (Dictionary<string, string>)stateData[CustomHeaderKey] : new Dictionary<string, string>();
+
+            // Start streaming session
             var claudeSession = new ClaudeSession();
             claudeSession.Contexts = messages;
-            claudeSession.StreamingTask = StartStreamingAsync(claudeSession, useFunctions, token);
+            claudeSession.StreamingTask = StartStreamingAsync(claudeSession, customParameters, customHeaders, useFunctions, token);
             await WaitForResponseType(claudeSession, token);
 
+            // Retry
             if (claudeSession.ResponseType == ResponseType.Timeout)
             {
                 if (retryCounter > 0)
@@ -104,7 +113,7 @@ public override async UniTask<ILLMSession> GenerateContentAsync(List<ILLMMessage
             return claudeSession;
         }
 
-        public virtual async UniTask StartStreamingAsync(ClaudeSession claudeSession, bool useFunctions = true, CancellationToken token = default)
+        public virtual async UniTask StartStreamingAsync(ClaudeSession claudeSession, Dictionary<string, string> customParameters, Dictionary<string, string> customHeaders, bool useFunctions = true, CancellationToken token = default)
         {
             // Make request data
             var data = new Dictionary<string, object>()
@@ -121,6 +130,10 @@ public virtual async UniTask StartStreamingAsync(ClaudeSession claudeSession, bo
             {
                 data.Add("top_k", TopK);
             }
+            foreach (var p in customParameters)
+            {
+                data[p.Key] = p.Value;
+            }
 
             // Prepare API request
             using var streamRequest = new UnityWebRequest(
@@ -132,6 +145,11 @@ public virtual async UniTask StartStreamingAsync(ClaudeSession claudeSession, bo
             streamRequest.SetRequestHeader("anthropic-beta", "messages-2023-12-15");
             streamRequest.SetRequestHeader("Content-Type", "application/json");
             streamRequest.SetRequestHeader("x-api-key", ApiKey);
+            foreach (var h in customHeaders)
+            {
+                streamRequest.SetRequestHeader(h.Key, h.Value);
+            }
+
             if (DebugMode)
             {
                 Debug.Log($"Request to Claude: {JsonConvert.SerializeObject(data)}");
diff --git a/Scripts/LLM/Claude/ClaudeServiceWebGL.cs b/Scripts/LLM/Claude/ClaudeServiceWebGL.cs
index 9775659..5b27e97 100644
--- a/Scripts/LLM/Claude/ClaudeServiceWebGL.cs
+++ b/Scripts/LLM/Claude/ClaudeServiceWebGL.cs
@@ -30,7 +30,7 @@ public override bool IsEnabled
         protected bool isChatCompletionJSDone { get; set; } = false;
         protected Dictionary<string, ClaudeSession> sessions { get; set; } = new Dictionary<string, ClaudeSession>();
 
-        public override async UniTask StartStreamingAsync(ClaudeSession claudeSession, bool useFunctions = true, CancellationToken token = default)
+        public override async UniTask StartStreamingAsync(ClaudeSession claudeSession, Dictionary<string, string> customParameters, Dictionary<string, string> customHeaders, bool useFunctions = true, CancellationToken token = default)
         {
             // Add session for callback
             var sessionId = Guid.NewGuid().ToString();
@@ -51,6 +51,16 @@ public override async UniTask StartStreamingAsync(ClaudeSession claudeSession, b
             {
                 data.Add("top_k", TopK);
             }
+            foreach (var p in customParameters)
+            {
+                data[p.Key] = p.Value;
+            }
+
+            // TODO: Support custom headers later...
+            if (customHeaders.Count >= 0)
+            {
+                Debug.LogWarning("Custom headers for Claude on WebGL is not supported for now.");
+            }
 
             // Start API stream
             isChatCompletionJSDone = false;
diff --git a/Scripts/LLM/Gemini/GeminiService.cs b/Scripts/LLM/Gemini/GeminiService.cs
index 416d79a..b4e0ea0 100644
--- a/Scripts/LLM/Gemini/GeminiService.cs
+++ b/Scripts/LLM/Gemini/GeminiService.cs
@@ -13,6 +13,8 @@ namespace ChatdollKit.LLM.Gemini
     public class GeminiService : LLMServiceBase
     {
         public string HistoryKey = "GeminiHistories";
+        public string CustomParameterKey = "GeminiParameters";
+        public string CustomHeaderKey = "GeminiHeaders";
 
         [Header("API configuration")]
         public string ApiKey;
@@ -117,9 +119,15 @@ public override async UniTask<List<ILLMMessage>> MakePromptAsync(string userId,
 
         public override async UniTask<ILLMSession> GenerateContentAsync(List<ILLMMessage> messages, Dictionary<string, object> payloads, bool useFunctions = true, int retryCounter = 1, CancellationToken token = default)
         {
+            // Custom parameters and headers
+            var stateData = (Dictionary<string, object>)payloads["StateData"];
+            var customParameters = stateData.ContainsKey(CustomParameterKey) ? (Dictionary<string, string>)stateData[CustomParameterKey] : new Dictionary<string, string>();
+            var customHeaders = stateData.ContainsKey(CustomHeaderKey) ? (Dictionary<string, string>)stateData[CustomHeaderKey] : new Dictionary<string, string>();
+
+            // Start streaming session
             var geminiSession = new GeminiSession();
             geminiSession.Contexts = messages;
-            geminiSession.StreamingTask = StartStreamingAsync(geminiSession, useFunctions, token);
+            geminiSession.StreamingTask = StartStreamingAsync(geminiSession, customParameters, customHeaders, useFunctions, token);
             await WaitForResponseType(geminiSession, token);
 
             if (geminiSession.ResponseType == ResponseType.Timeout)
@@ -140,7 +148,7 @@ public override async UniTask<ILLMSession> GenerateContentAsync(List<ILLMMessage
             return geminiSession;
         }
 
-        public virtual async UniTask StartStreamingAsync(GeminiSession geminiSession, bool useFunctions = true, CancellationToken token = default)
+        public virtual async UniTask StartStreamingAsync(GeminiSession geminiSession, Dictionary<string, string> customParameters, Dictionary<string, string> customHeaders, bool useFunctions = true, CancellationToken token = default)
         {
             // GenerationConfig
             var generationConfig = new GeminiGenerationConfig()
@@ -158,6 +166,10 @@ public virtual async UniTask StartStreamingAsync(GeminiSession geminiSession, bo
                 { "contents", geminiSession.Contexts },
                 { "generationConfig", generationConfig }
             };
+            foreach (var p in customParameters)
+            {
+                data[p.Key] = p.Value;
+            }
 
             // Set tools. Multimodal model doesn't support function calling for now (2023.12.29)
             if (useFunctions && llmTools.Count > 0 && !Model.ToLower().Contains("vision"))
@@ -176,6 +188,11 @@ public virtual async UniTask StartStreamingAsync(GeminiSession geminiSession, bo
             );
             streamRequest.timeout = responseTimeoutSec;
             streamRequest.SetRequestHeader("Content-Type", "application/json");
+            foreach (var h in customHeaders)
+            {
+                streamRequest.SetRequestHeader(h.Key, h.Value);
+            }
+
             if (DebugMode)
             {
                 Debug.Log($"Request to Gemini: {JsonConvert.SerializeObject(data)}");
diff --git a/Scripts/LLM/Gemini/GeminiServiceWebGL.cs b/Scripts/LLM/Gemini/GeminiServiceWebGL.cs
index 3f0c8ba..c8c22b9 100644
--- a/Scripts/LLM/Gemini/GeminiServiceWebGL.cs
+++ b/Scripts/LLM/Gemini/GeminiServiceWebGL.cs
@@ -30,7 +30,7 @@ public override bool IsEnabled
         protected bool isChatCompletionJSDone { get; set; } = false;
         protected Dictionary<string, GeminiSession> sessions { get; set; } = new Dictionary<string, GeminiSession>();
 
-        public override async UniTask StartStreamingAsync(GeminiSession geminiSession, bool useFunctions = true, CancellationToken token = default)
+        public override async UniTask StartStreamingAsync(GeminiSession geminiSession, Dictionary<string, string> customParameters, Dictionary<string, string> customHeaders, bool useFunctions = true, CancellationToken token = default)
         {
             // Add session for callback
             var sessionId = Guid.NewGuid().ToString();
@@ -52,6 +52,16 @@ public override async UniTask StartStreamingAsync(GeminiSession geminiSession, b
                 { "contents", geminiSession.Contexts },
                 { "generationConfig", generationConfig }
             };
+            foreach (var p in customParameters)
+            {
+                data[p.Key] = p.Value;
+            }
+
+            // TODO: Support custom headers later...
+            if (customHeaders.Count >= 0)
+            {
+                Debug.LogWarning("Custom headers for Gemini on WebGL is not supported for now.");
+            }
 
             // Set tools. Multimodal model doesn't support function calling for now (2023.12.29)
             if (useFunctions && llmTools.Count > 0 && !Model.ToLower().Contains("vision"))