diff --git a/nah/src/chat.rs b/nah/src/chat.rs
index ca48537..f277d38 100644
--- a/nah/src/chat.rs
+++ b/nah/src/chat.rs
@@ -17,7 +17,7 @@ use crate::AppContext;
 use crate::ModelConfig;
 use futures_util::pin_mut;
 use futures_util::stream::StreamExt;
-use nah_chat::{ChatClient, ChatMessage, ToolCallRequest};
+use nah_chat::{ChatClient, ChatCompletionParamsBuilder, ChatMessage, ToolCallRequest};
 use serde_json::{json, Value};
 use std::fs::{File, OpenOptions};
 use tokio::runtime::{Builder, Runtime};
@@ -197,14 +197,13 @@ impl ChatContext {
    * Generate assistant message.
    */
   pub fn generate(&mut self) -> Result<&ChatMessage, NahError> {
-    let mut params = HashMap::from([
-      ("max_token".to_owned(), json!(4096)),
-      ("tools".to_owned(), json!(self.tools.clone())),
-      ("n".to_owned(), json!(1)),
-      ("temperature".to_owned(), json!(0.7)),
-      ("top_p".to_owned(), json!(0.9)),
-      ("frequency_penalty".to_owned(), json!(0.5)),
-    ]);
+    let mut params_builder = ChatCompletionParamsBuilder::new();
+    params_builder
+      .max_token(4096)
+      .temperature(0.7)
+      .top_p(0.9)
+      .frequency_penalty(0.5)
+      .insert("tools", json!(self.tools.clone()));
 
     self
       .model_config
@@ -213,7 +212,7 @@ impl ChatContext {
       .and_then(|v| v.as_object())
       .and_then(|extra_params| {
         extra_params.iter().for_each(|(key, value)| {
-          params.insert(key.to_owned(), value.to_owned());
+          params_builder.insert(key, value.to_owned());
         });
         Some(())
       });
@@ -221,7 +220,7 @@ impl ChatContext {
     let message: Result<ChatMessage, NahError> = self.tokio_runtime.block_on(async {
       let stream = match self
         .chat_client
-        .chat_completion_stream(&self.model_config.model, &self.messages, &params)
+        .chat_completion_stream(&self.model_config.model, &self.messages, &params_builder)
         .await
       {
         Ok(s) => s,
diff --git a/nah_chat/src/lib.rs b/nah_chat/src/lib.rs
index 987b07e..f314fd6 100644
--- a/nah_chat/src/lib.rs
+++ b/nah_chat/src/lib.rs
@@ -61,7 +61,7 @@ use async_stream::stream;
 use bytes::Bytes;
 use futures_core::stream::Stream;
 use serde::{Deserialize, Serialize};
-use serde_json::{Value, json};
+use serde_json::{Number, Value, json};
 
 /**
  * Error kinds that may occur in `nah_chat`.
@@ -282,6 +282,93 @@ pub struct FunctionCallRequestChunkDelta {
   pub arguments: Option<String>,
 }
 
+/**
+ * A builder for creating parameters for chat completion requests.
+ */
+#[derive(Debug, Clone)]
+pub struct ChatCompletionParamsBuilder {
+  data: std::collections::HashMap<String, Value>,
+}
+
+impl ChatCompletionParamsBuilder {
+  /**
+   * Initialize a [ChatCompletionParamsBuilder] object.
+   */
+  pub fn new() -> Self {
+    ChatCompletionParamsBuilder {
+      data: std::collections::HashMap::new(),
+    }
+  }
+
+  /**
+   * Consume the data builder to get a hash map of the parameters for chat completion requests.
+   */
+  pub fn build(self) -> std::collections::HashMap<String, Value> {
+    self.data
+  }
+
+  /**
+   * Set max token parameter.
+   */
+  pub fn max_token(&mut self, n: usize) -> &mut Self {
+    self.data.insert(
+      "max_token".to_owned(),
+      Value::Number(Number::from_u128(n as u128).unwrap()),
+    );
+    self
+  }
+
+  /**
+   * Set temperature parameter.
+   */
+  pub fn temperature(&mut self, t: f64) -> &mut Self {
+    self.data.insert(
+      "temperature".to_owned(),
+      Value::Number(Number::from_f64(t).unwrap()),
+    );
+    self
+  }
+
+  /**
+   * Set top_p parameter.
+   */
+  pub fn top_p(&mut self, p: f64) -> &mut Self {
+    self.data.insert(
+      "top_p".to_owned(),
+      Value::Number(Number::from_f64(p).unwrap()),
+    );
+    self
+  }
+
+  /**
+   * Set frequency_penalty parameter.
+   */
+  pub fn frequency_penalty(&mut self, p: f64) -> &mut Self {
+    self.data.insert(
+      "frequency_penalty".to_owned(),
+      Value::Number(Number::from_f64(p).unwrap()),
+    );
+    self
+  }
+
+  /**
+   * Set a parameter with key of `name` and value of `value`.
+   */
+  pub fn insert(&mut self, name: &str, value: Value) -> &mut Self {
+    self.data.insert(name.to_owned(), value);
+    self
+  }
+}
+
+impl<'a> std::iter::IntoIterator for &'a ChatCompletionParamsBuilder {
+  type Item = (&'a String, &'a Value);
+  type IntoIter = std::collections::hash_map::Iter<'a, String, Value>;
+
+  fn into_iter(self) -> Self::IntoIter {
+    (&self.data).into_iter()
+  }
+}
+
 /**
  * The object to hold information about the model server and `reqwest` HTTP client.
  */