diff --git a/Cargo.toml b/Cargo.toml
index 9ae5a37..38979df 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "openai-api-rs"
-version = "5.2.4"
+version = "6.0.0"
 edition = "2021"
 authors = ["Dongri Jin <dongrium@gmail.com>"]
 license = "MIT"
diff --git a/README.md b/README.md
index f2f2d27..03dfb95 100644
--- a/README.md
+++ b/README.md
@@ -7,21 +7,32 @@ Check out the [docs.rs](https://docs.rs/openai-api-rs/).
 Cargo.toml
 ```toml
 [dependencies]
-openai-api-rs = "5.2.4"
+openai-api-rs = "6.0.0"
 ```
 
 ## Usage
 The library needs to be configured with your account's secret key, which is available on the [website](https://platform.openai.com/account/api-keys). We recommend setting it as an environment variable. Here's an example of initializing the library with the API key loaded from an environment variable and creating a completion:
 
-### Set OPENAI_API_KEY to environment variable
+### Set OPENAI_API_KEY or OPENROUTER_API_KEY to environment variable
 ```bash
 $ export OPENAI_API_KEY=sk-xxxxxxx
+or
+$ export OPENROUTER_API_KEY=sk-xxxxxxx
 ```
 
-### Create client
+### Create OpenAI client
 ```rust
 let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
+```
+
+### Create OpenRouter client
+```rust
+let api_key = env::var("OPENROUTER_API_KEY").unwrap().to_string();
+let mut client = OpenAIClient::builder()
+    .with_endpoint("https://openrouter.ai/api/v1")
+    .with_api_key(api_key)
+    .build()?;
 ```
 
 ### Create request
@@ -42,6 +53,10 @@ let req = ChatCompletionRequest::new(
 ```rust
 let result = client.chat_completion(req)?;
 println!("Content: {:?}", result.choices[0].message.content);
+
+for (key, value) in client.headers.unwrap().iter() {
+    println!("{}: {:?}", key, value);
+}
 ```
 
 ### Set OPENAI_API_BASE to environment variable (optional)
@@ -59,7 +74,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = ChatCompletionRequest::new(
         GPT4_O.to_string(),
@@ -74,11 +89,52 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let result = client.chat_completion(req).await?;
     println!("Content: {:?}", result.choices[0].message.content);
-    println!("Response Headers: {:?}", result.headers);
+
+    for (key, value) in client.headers.unwrap().iter() {
+        println!("{}: {:?}", key, value);
+    }
 
     Ok(())
 }
 ```
+
+## Example for OpenRouter
+```rust
+use openai_api_rs::v1::api::OpenAIClient;
+use openai_api_rs::v1::chat_completion::{self, ChatCompletionRequest};
+use openai_api_rs::v1::common::GPT4_O_MINI;
+use std::env;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let api_key = env::var("OPENROUTER_API_KEY").unwrap().to_string();
+    let mut client = OpenAIClient::builder()
+        .with_endpoint("https://openrouter.ai/api/v1")
+        .with_api_key(api_key)
+        .build()?;
+
+    let req = ChatCompletionRequest::new(
+        GPT4_O_MINI.to_string(),
+        vec![chat_completion::ChatCompletionMessage {
+            role: chat_completion::MessageRole::user,
+            content: chat_completion::Content::Text(String::from("What is bitcoin?")),
+            name: None,
+            tool_calls: None,
+            tool_call_id: None,
+        }],
+    );
+
+    let result = client.chat_completion(req).await?;
+    println!("Content: {:?}", result.choices[0].message.content);
+    
+    for (key, value) in client.headers.unwrap().iter() {
+        println!("{}: {:?}", key, value);
+    }
+
+    Ok(())
+}
+```
+
 More Examples: [examples](https://github.com/dongri/openai-api-rs/tree/main/examples)
 
 Check out the [full API documentation](https://platform.openai.com/docs/api-reference/completions) for examples of all the available functions.
diff --git a/examples/assistant.rs b/examples/assistant.rs
index 2e212b8..b7573e6 100644
--- a/examples/assistant.rs
+++ b/examples/assistant.rs
@@ -10,7 +10,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let mut tools = HashMap::new();
     tools.insert("type".to_string(), "code_interpreter".to_string());
diff --git a/examples/audio_speech.rs b/examples/audio_speech.rs
index 9e3af08..7df168f 100644
--- a/examples/audio_speech.rs
+++ b/examples/audio_speech.rs
@@ -5,7 +5,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = AudioSpeechRequest::new(
         TTS_1.to_string(),
diff --git a/examples/audio_transcriptions.rs b/examples/audio_transcriptions.rs
index 49f5b88..2c341de 100644
--- a/examples/audio_transcriptions.rs
+++ b/examples/audio_transcriptions.rs
@@ -1,16 +1,18 @@
 use openai_api_rs::v1::api::OpenAIClient;
 use openai_api_rs::v1::audio::{AudioTranscriptionRequest, WHISPER_1};
 use std::env;
+use std::fs::File;
+use std::io::Read;
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
-    let req = AudioTranscriptionRequest::new(
-        "examples/data/problem.mp3".to_string(),
-        WHISPER_1.to_string(),
-    );
+    let file_path = "examples/data/problem.mp3";
+
+    // Test with file
+    let req = AudioTranscriptionRequest::new(file_path.to_string(), WHISPER_1.to_string());
 
     let req_json = req.clone().response_format("json".to_string());
 
@@ -22,7 +24,19 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let result = client.audio_transcription_raw(req_raw).await?;
     println!("{:?}", result);
 
+    // Test with bytes
+    let mut file = File::open(file_path)?;
+    let mut buffer = Vec::new();
+    file.read_to_end(&mut buffer)?;
+
+    let req = AudioTranscriptionRequest::new_bytes(buffer, WHISPER_1.to_string());
+
+    let req_json = req.clone().response_format("json".to_string());
+
+    let result = client.audio_transcription(req_json).await?;
+    println!("{:?}", result);
+
     Ok(())
 }
 
-// OPENAI_API_KEY=xxxx cargo run --package openai-api-rs --example audio_translations
+// OPENAI_API_KEY=xxxx cargo run --package openai-api-rs --example audio_transcriptions
diff --git a/examples/audio_translations.rs b/examples/audio_translations.rs
index 13b57e0..d352b65 100644
--- a/examples/audio_translations.rs
+++ b/examples/audio_translations.rs
@@ -5,7 +5,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = AudioTranslationRequest::new(
         "examples/data/problem_cn.mp3".to_string(),
diff --git a/examples/batch.rs b/examples/batch.rs
index f14617e..aca5784 100644
--- a/examples/batch.rs
+++ b/examples/batch.rs
@@ -10,7 +10,7 @@ use std::str;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = FileUploadRequest::new(
         "examples/data/batch_request.json".to_string(),
diff --git a/examples/chat_completion.rs b/examples/chat_completion.rs
index 7a5791c..64f564e 100644
--- a/examples/chat_completion.rs
+++ b/examples/chat_completion.rs
@@ -6,7 +6,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = ChatCompletionRequest::new(
         GPT4_O_MINI.to_string(),
@@ -21,7 +21,11 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let result = client.chat_completion(req).await?;
     println!("Content: {:?}", result.choices[0].message.content);
-    println!("Response Headers: {:?}", result.headers);
+
+    // print response headers
+    for (key, value) in client.headers.unwrap().iter() {
+        println!("{}: {:?}", key, value);
+    }
 
     Ok(())
 }
diff --git a/examples/completion.rs b/examples/completion.rs
index 138c1fe..95cbc23 100644
--- a/examples/completion.rs
+++ b/examples/completion.rs
@@ -5,7 +5,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = CompletionRequest::new(
         completion::GPT3_TEXT_DAVINCI_003.to_string(),
diff --git a/examples/embedding.rs b/examples/embedding.rs
index 8615bdb..23ca6db 100644
--- a/examples/embedding.rs
+++ b/examples/embedding.rs
@@ -6,7 +6,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let mut req = EmbeddingRequest::new(
         TEXT_EMBEDDING_3_SMALL.to_string(),
diff --git a/examples/function_call.rs b/examples/function_call.rs
index 1858465..06bd922 100644
--- a/examples/function_call.rs
+++ b/examples/function_call.rs
@@ -18,7 +18,7 @@ fn get_coin_price(coin: &str) -> f64 {
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let mut properties = HashMap::new();
     properties.insert(
diff --git a/examples/function_call_role.rs b/examples/function_call_role.rs
index 1afc91a..46148f4 100644
--- a/examples/function_call_role.rs
+++ b/examples/function_call_role.rs
@@ -18,7 +18,7 @@ fn get_coin_price(coin: &str) -> f64 {
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let mut properties = HashMap::new();
     properties.insert(
diff --git a/examples/openrouter.rs b/examples/openrouter.rs
new file mode 100644
index 0000000..dd04e0a
--- /dev/null
+++ b/examples/openrouter.rs
@@ -0,0 +1,32 @@
+use openai_api_rs::v1::api::OpenAIClient;
+use openai_api_rs::v1::chat_completion::{self, ChatCompletionRequest};
+use openai_api_rs::v1::common::GPT4_O_MINI;
+use std::env;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let api_key = env::var("OPENROUTER_API_KEY").unwrap().to_string();
+    let mut client = OpenAIClient::builder()
+        .with_endpoint("https://openrouter.ai/api/v1")
+        .with_api_key(api_key)
+        .build()?;
+
+    let req = ChatCompletionRequest::new(
+        GPT4_O_MINI.to_string(),
+        vec![chat_completion::ChatCompletionMessage {
+            role: chat_completion::MessageRole::user,
+            content: chat_completion::Content::Text(String::from("What is bitcoin?")),
+            name: None,
+            tool_calls: None,
+            tool_call_id: None,
+        }],
+    );
+
+    let result = client.chat_completion(req).await?;
+    println!("Content: {:?}", result.choices[0].message.content);
+    println!("Response Headers: {:?}", client.headers);
+
+    Ok(())
+}
+
+// OPENROUTER_API_KEY=xxxx cargo run --package openai-api-rs --example openrouter
diff --git a/examples/vision.rs b/examples/vision.rs
index 6a92c43..7bad362 100644
--- a/examples/vision.rs
+++ b/examples/vision.rs
@@ -6,7 +6,7 @@ use std::env;
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let api_key = env::var("OPENAI_API_KEY").unwrap().to_string();
-    let client = OpenAIClient::builder().with_api_key(api_key).build()?;
+    let mut client = OpenAIClient::builder().with_api_key(api_key).build()?;
 
     let req = ChatCompletionRequest::new(
         GPT4_O.to_string(),
diff --git a/src/realtime/types.rs b/src/realtime/types.rs
index 0cc70d9..a9df8bd 100644
--- a/src/realtime/types.rs
+++ b/src/realtime/types.rs
@@ -30,17 +30,22 @@ pub struct Session {
 #[serde(rename_all = "lowercase")]
 pub enum RealtimeVoice {
     Alloy,
-    Shimmer,
+    Ash,
+    Ballad,
+    Coral,
     Echo,
+    Sage,
+    Shimmer,
+    Verse,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub enum AudioFormat {
     #[serde(rename = "pcm16")]
     PCM16,
-    #[serde(rename = "g711-ulaw")]
+    #[serde(rename = "g711_ulaw")]
     G711ULAW,
-    #[serde(rename = "g711-alaw")]
+    #[serde(rename = "g711_alaw")]
     G711ALAW,
 }
 
diff --git a/src/v1/api.rs b/src/v1/api.rs
index f669cca..c53f989 100644
--- a/src/v1/api.rs
+++ b/src/v1/api.rs
@@ -68,7 +68,7 @@ pub struct OpenAIClient {
     organization: Option<String>,
     proxy: Option<String>,
     timeout: Option<u64>,
-    headers: Option<HeaderMap>,
+    pub headers: Option<HeaderMap>,
 }
 
 impl OpenAIClientBuilder {
@@ -136,6 +136,9 @@ impl OpenAIClient {
         let url = format!("{}/{}", self.api_endpoint, path);
         let client = Client::builder();
 
+        #[cfg(feature = "rustls")]
+        let client = client.use_rustls_tls();
+
         let client = if let Some(timeout) = self.timeout {
             client.timeout(std::time::Duration::from_secs(timeout))
         } else {
@@ -172,7 +175,7 @@ impl OpenAIClient {
     }
 
     async fn post<T: serde::de::DeserializeOwned>(
-        &self,
+        &mut self,
         path: &str,
         body: &impl serde::ser::Serialize,
     ) -> Result<T, APIError> {
@@ -182,7 +185,7 @@ impl OpenAIClient {
         self.handle_response(response).await
     }
 
-    async fn get<T: serde::de::DeserializeOwned>(&self, path: &str) -> Result<T, APIError> {
+    async fn get<T: serde::de::DeserializeOwned>(&mut self, path: &str) -> Result<T, APIError> {
         let request = self.build_request(Method::GET, path).await;
         let response = request.send().await?;
         self.handle_response(response).await
@@ -194,14 +197,14 @@ impl OpenAIClient {
         Ok(response.bytes().await?)
     }
 
-    async fn delete<T: serde::de::DeserializeOwned>(&self, path: &str) -> Result<T, APIError> {
+    async fn delete<T: serde::de::DeserializeOwned>(&mut self, path: &str) -> Result<T, APIError> {
         let request = self.build_request(Method::DELETE, path).await;
         let response = request.send().await?;
         self.handle_response(response).await
     }
 
     async fn post_form<T: serde::de::DeserializeOwned>(
-        &self,
+        &mut self,
         path: &str,
         form: Form,
     ) -> Result<T, APIError> {
@@ -219,14 +222,18 @@ impl OpenAIClient {
     }
 
     async fn handle_response<T: serde::de::DeserializeOwned>(
-        &self,
+        &mut self,
         response: Response,
     ) -> Result<T, APIError> {
         let status = response.status();
+        let headers = response.headers().clone();
         if status.is_success() {
             let text = response.text().await.unwrap_or_else(|_| "".to_string());
             match serde_json::from_str::<T>(&text) {
-                Ok(parsed) => Ok(parsed),
+                Ok(parsed) => {
+                    self.headers = Some(headers);
+                    Ok(parsed)
+                }
                 Err(e) => Err(APIError::CustomError {
                     message: format!("Failed to parse JSON: {} / response {}", e, text),
                 }),
@@ -242,42 +249,51 @@ impl OpenAIClient {
         }
     }
 
-    pub async fn completion(&self, req: CompletionRequest) -> Result<CompletionResponse, APIError> {
+    pub async fn completion(
+        &mut self,
+        req: CompletionRequest,
+    ) -> Result<CompletionResponse, APIError> {
         self.post("completions", &req).await
     }
 
-    pub async fn edit(&self, req: EditRequest) -> Result<EditResponse, APIError> {
+    pub async fn edit(&mut self, req: EditRequest) -> Result<EditResponse, APIError> {
         self.post("edits", &req).await
     }
 
     pub async fn image_generation(
-        &self,
+        &mut self,
         req: ImageGenerationRequest,
     ) -> Result<ImageGenerationResponse, APIError> {
         self.post("images/generations", &req).await
     }
 
-    pub async fn image_edit(&self, req: ImageEditRequest) -> Result<ImageEditResponse, APIError> {
+    pub async fn image_edit(
+        &mut self,
+        req: ImageEditRequest,
+    ) -> Result<ImageEditResponse, APIError> {
         self.post("images/edits", &req).await
     }
 
     pub async fn image_variation(
-        &self,
+        &mut self,
         req: ImageVariationRequest,
     ) -> Result<ImageVariationResponse, APIError> {
         self.post("images/variations", &req).await
     }
 
-    pub async fn embedding(&self, req: EmbeddingRequest) -> Result<EmbeddingResponse, APIError> {
+    pub async fn embedding(
+        &mut self,
+        req: EmbeddingRequest,
+    ) -> Result<EmbeddingResponse, APIError> {
         self.post("embeddings", &req).await
     }
 
-    pub async fn file_list(&self) -> Result<FileListResponse, APIError> {
+    pub async fn file_list(&mut self) -> Result<FileListResponse, APIError> {
         self.get("files").await
     }
 
     pub async fn upload_file(
-        &self,
+        &mut self,
         req: FileUploadRequest,
     ) -> Result<FileUploadResponse, APIError> {
         let form = Self::create_form(&req, "file")?;
@@ -285,13 +301,16 @@ impl OpenAIClient {
     }
 
     pub async fn delete_file(
-        &self,
+        &mut self,
         req: FileDeleteRequest,
     ) -> Result<FileDeleteResponse, APIError> {
         self.delete(&format!("files/{}", req.file_id)).await
     }
 
-    pub async fn retrieve_file(&self, file_id: String) -> Result<FileRetrieveResponse, APIError> {
+    pub async fn retrieve_file(
+        &mut self,
+        file_id: String,
+    ) -> Result<FileRetrieveResponse, APIError> {
         self.get(&format!("files/{}", file_id)).await
     }
 
@@ -300,17 +319,17 @@ impl OpenAIClient {
     }
 
     pub async fn chat_completion(
-        &self,
+        &mut self,
         req: ChatCompletionRequest,
     ) -> Result<ChatCompletionResponse, APIError> {
         self.post("chat/completions", &req).await
     }
 
     pub async fn audio_transcription(
-        &self,
+        &mut self,
         req: AudioTranscriptionRequest,
     ) -> Result<AudioTranscriptionResponse, APIError> {
-        // https://platform.openai.com/docs/api-reference/audio/createTranslation#audio-createtranslation-response_format
+        // https://platform.openai.com/docs/api-reference/audio/createTranscription#audio-createtranscription-response_format
         if let Some(response_format) = &req.response_format {
             if response_format != "json" && response_format != "verbose_json" {
                 return Err(APIError::CustomError {
@@ -318,15 +337,24 @@ impl OpenAIClient {
                 });
             }
         }
-        let form = Self::create_form(&req, "file")?;
+        let form: Form;
+        if req.clone().file.is_some() {
+            form = Self::create_form(&req, "file")?;
+        } else if let Some(bytes) = req.clone().bytes {
+            form = Self::create_form_from_bytes(&req, bytes)?;
+        } else {
+            return Err(APIError::CustomError {
+                message: "Either file or bytes must be provided".to_string(),
+            });
+        }
         self.post_form("audio/transcriptions", form).await
     }
 
     pub async fn audio_transcription_raw(
-        &self,
+        &mut self,
         req: AudioTranscriptionRequest,
     ) -> Result<Bytes, APIError> {
-        // https://platform.openai.com/docs/api-reference/audio/createTranslation#audio-createtranslation-response_format
+        // https://platform.openai.com/docs/api-reference/audio/createTranscription#audio-createtranscription-response_format
         if let Some(response_format) = &req.response_format {
             if response_format != "text" && response_format != "srt" && response_format != "vtt" {
                 return Err(APIError::CustomError {
@@ -334,12 +362,21 @@ impl OpenAIClient {
                 });
             }
         }
-        let form = Self::create_form(&req, "file")?;
+        let form: Form;
+        if req.clone().file.is_some() {
+            form = Self::create_form(&req, "file")?;
+        } else if let Some(bytes) = req.clone().bytes {
+            form = Self::create_form_from_bytes(&req, bytes)?;
+        } else {
+            return Err(APIError::CustomError {
+                message: "Either file or bytes must be provided".to_string(),
+            });
+        }
         self.post_form_raw("audio/transcriptions", form).await
     }
 
     pub async fn audio_translation(
-        &self,
+        &mut self,
         req: AudioTranslationRequest,
     ) -> Result<AudioTranslationResponse, APIError> {
         let form = Self::create_form(&req, "file")?;
@@ -347,7 +384,7 @@ impl OpenAIClient {
     }
 
     pub async fn audio_speech(
-        &self,
+        &mut self,
         req: AudioSpeechRequest,
     ) -> Result<AudioSpeechResponse, APIError> {
         let request = self.build_request(Method::POST, "audio/speech").await;
@@ -389,20 +426,20 @@ impl OpenAIClient {
     }
 
     pub async fn create_fine_tuning_job(
-        &self,
+        &mut self,
         req: CreateFineTuningJobRequest,
     ) -> Result<FineTuningJobObject, APIError> {
         self.post("fine_tuning/jobs", &req).await
     }
 
     pub async fn list_fine_tuning_jobs(
-        &self,
+        &mut self,
     ) -> Result<FineTuningPagination<FineTuningJobObject>, APIError> {
         self.get("fine_tuning/jobs").await
     }
 
     pub async fn list_fine_tuning_job_events(
-        &self,
+        &mut self,
         req: ListFineTuningJobEventsRequest,
     ) -> Result<FineTuningPagination<FineTuningJobEvent>, APIError> {
         self.get(&format!(
@@ -413,7 +450,7 @@ impl OpenAIClient {
     }
 
     pub async fn retrieve_fine_tuning_job(
-        &self,
+        &mut self,
         req: RetrieveFineTuningJobRequest,
     ) -> Result<FineTuningJobObject, APIError> {
         self.get(&format!("fine_tuning/jobs/{}", req.fine_tuning_job_id))
@@ -421,7 +458,7 @@ impl OpenAIClient {
     }
 
     pub async fn cancel_fine_tuning_job(
-        &self,
+        &mut self,
         req: CancelFineTuningJobRequest,
     ) -> Result<FineTuningJobObject, APIError> {
         self.post(
@@ -432,28 +469,28 @@ impl OpenAIClient {
     }
 
     pub async fn create_moderation(
-        &self,
+        &mut self,
         req: CreateModerationRequest,
     ) -> Result<CreateModerationResponse, APIError> {
         self.post("moderations", &req).await
     }
 
     pub async fn create_assistant(
-        &self,
+        &mut self,
         req: AssistantRequest,
     ) -> Result<AssistantObject, APIError> {
         self.post("assistants", &req).await
     }
 
     pub async fn retrieve_assistant(
-        &self,
+        &mut self,
         assistant_id: String,
     ) -> Result<AssistantObject, APIError> {
         self.get(&format!("assistants/{}", assistant_id)).await
     }
 
     pub async fn modify_assistant(
-        &self,
+        &mut self,
         assistant_id: String,
         req: AssistantRequest,
     ) -> Result<AssistantObject, APIError> {
@@ -461,12 +498,15 @@ impl OpenAIClient {
             .await
     }
 
-    pub async fn delete_assistant(&self, assistant_id: String) -> Result<DeletionStatus, APIError> {
+    pub async fn delete_assistant(
+        &mut self,
+        assistant_id: String,
+    ) -> Result<DeletionStatus, APIError> {
         self.delete(&format!("assistants/{}", assistant_id)).await
     }
 
     pub async fn list_assistant(
-        &self,
+        &mut self,
         limit: Option<i64>,
         order: Option<String>,
         after: Option<String>,
@@ -477,7 +517,7 @@ impl OpenAIClient {
     }
 
     pub async fn create_assistant_file(
-        &self,
+        &mut self,
         assistant_id: String,
         req: AssistantFileRequest,
     ) -> Result<AssistantFileObject, APIError> {
@@ -486,7 +526,7 @@ impl OpenAIClient {
     }
 
     pub async fn retrieve_assistant_file(
-        &self,
+        &mut self,
         assistant_id: String,
         file_id: String,
     ) -> Result<AssistantFileObject, APIError> {
@@ -495,7 +535,7 @@ impl OpenAIClient {
     }
 
     pub async fn delete_assistant_file(
-        &self,
+        &mut self,
         assistant_id: String,
         file_id: String,
     ) -> Result<DeletionStatus, APIError> {
@@ -504,7 +544,7 @@ impl OpenAIClient {
     }
 
     pub async fn list_assistant_file(
-        &self,
+        &mut self,
         assistant_id: String,
         limit: Option<i64>,
         order: Option<String>,
@@ -521,28 +561,31 @@ impl OpenAIClient {
         self.get(&url).await
     }
 
-    pub async fn create_thread(&self, req: CreateThreadRequest) -> Result<ThreadObject, APIError> {
+    pub async fn create_thread(
+        &mut self,
+        req: CreateThreadRequest,
+    ) -> Result<ThreadObject, APIError> {
         self.post("threads", &req).await
     }
 
-    pub async fn retrieve_thread(&self, thread_id: String) -> Result<ThreadObject, APIError> {
+    pub async fn retrieve_thread(&mut self, thread_id: String) -> Result<ThreadObject, APIError> {
         self.get(&format!("threads/{}", thread_id)).await
     }
 
     pub async fn modify_thread(
-        &self,
+        &mut self,
         thread_id: String,
         req: ModifyThreadRequest,
     ) -> Result<ThreadObject, APIError> {
         self.post(&format!("threads/{}", thread_id), &req).await
     }
 
-    pub async fn delete_thread(&self, thread_id: String) -> Result<DeletionStatus, APIError> {
+    pub async fn delete_thread(&mut self, thread_id: String) -> Result<DeletionStatus, APIError> {
         self.delete(&format!("threads/{}", thread_id)).await
     }
 
     pub async fn create_message(
-        &self,
+        &mut self,
         thread_id: String,
         req: CreateMessageRequest,
     ) -> Result<MessageObject, APIError> {
@@ -551,7 +594,7 @@ impl OpenAIClient {
     }
 
     pub async fn retrieve_message(
-        &self,
+        &mut self,
         thread_id: String,
         message_id: String,
     ) -> Result<MessageObject, APIError> {
@@ -560,7 +603,7 @@ impl OpenAIClient {
     }
 
     pub async fn modify_message(
-        &self,
+        &mut self,
         thread_id: String,
         message_id: String,
         req: ModifyMessageRequest,
@@ -572,12 +615,12 @@ impl OpenAIClient {
         .await
     }
 
-    pub async fn list_messages(&self, thread_id: String) -> Result<ListMessage, APIError> {
+    pub async fn list_messages(&mut self, thread_id: String) -> Result<ListMessage, APIError> {
         self.get(&format!("threads/{}/messages", thread_id)).await
     }
 
     pub async fn retrieve_message_file(
-        &self,
+        &mut self,
         thread_id: String,
         message_id: String,
         file_id: String,
@@ -590,7 +633,7 @@ impl OpenAIClient {
     }
 
     pub async fn list_message_file(
-        &self,
+        &mut self,
         thread_id: String,
         message_id: String,
         limit: Option<i64>,
@@ -609,7 +652,7 @@ impl OpenAIClient {
     }
 
     pub async fn create_run(
-        &self,
+        &mut self,
         thread_id: String,
         req: CreateRunRequest,
     ) -> Result<RunObject, APIError> {
@@ -618,7 +661,7 @@ impl OpenAIClient {
     }
 
     pub async fn retrieve_run(
-        &self,
+        &mut self,
         thread_id: String,
         run_id: String,
     ) -> Result<RunObject, APIError> {
@@ -627,7 +670,7 @@ impl OpenAIClient {
     }
 
     pub async fn modify_run(
-        &self,
+        &mut self,
         thread_id: String,
         run_id: String,
         req: ModifyRunRequest,
@@ -637,7 +680,7 @@ impl OpenAIClient {
     }
 
     pub async fn list_run(
-        &self,
+        &mut self,
         thread_id: String,
         limit: Option<i64>,
         order: Option<String>,
@@ -655,7 +698,7 @@ impl OpenAIClient {
     }
 
     pub async fn cancel_run(
-        &self,
+        &mut self,
         thread_id: String,
         run_id: String,
     ) -> Result<RunObject, APIError> {
@@ -667,14 +710,14 @@ impl OpenAIClient {
     }
 
     pub async fn create_thread_and_run(
-        &self,
+        &mut self,
         req: CreateThreadAndRunRequest,
     ) -> Result<RunObject, APIError> {
         self.post("threads/runs", &req).await
     }
 
     pub async fn retrieve_run_step(
-        &self,
+        &mut self,
         thread_id: String,
         run_id: String,
         step_id: String,
@@ -687,7 +730,7 @@ impl OpenAIClient {
     }
 
     pub async fn list_run_step(
-        &self,
+        &mut self,
         thread_id: String,
         run_id: String,
         limit: Option<i64>,
@@ -705,15 +748,18 @@ impl OpenAIClient {
         self.get(&url).await
     }
 
-    pub async fn create_batch(&self, req: CreateBatchRequest) -> Result<BatchResponse, APIError> {
+    pub async fn create_batch(
+        &mut self,
+        req: CreateBatchRequest,
+    ) -> Result<BatchResponse, APIError> {
         self.post("batches", &req).await
     }
 
-    pub async fn retrieve_batch(&self, batch_id: String) -> Result<BatchResponse, APIError> {
+    pub async fn retrieve_batch(&mut self, batch_id: String) -> Result<BatchResponse, APIError> {
         self.get(&format!("batches/{}", batch_id)).await
     }
 
-    pub async fn cancel_batch(&self, batch_id: String) -> Result<BatchResponse, APIError> {
+    pub async fn cancel_batch(&mut self, batch_id: String) -> Result<BatchResponse, APIError> {
         self.post(
             &format!("batches/{}/cancel", batch_id),
             &common::EmptyRequestBody {},
@@ -722,7 +768,7 @@ impl OpenAIClient {
     }
 
     pub async fn list_batch(
-        &self,
+        &mut self,
         after: Option<String>,
         limit: Option<i64>,
     ) -> Result<ListBatchResponse, APIError> {
@@ -823,4 +869,36 @@ impl OpenAIClient {
 
         Ok(form)
     }
+
+    fn create_form_from_bytes<T>(req: &T, bytes: Vec<u8>) -> Result<Form, APIError>
+    where
+        T: Serialize,
+    {
+        let json = match serde_json::to_value(req) {
+            Ok(json) => json,
+            Err(e) => {
+                return Err(APIError::CustomError {
+                    message: e.to_string(),
+                })
+            }
+        };
+
+        let mut form = Form::new().part("file", Part::bytes(bytes.clone()).file_name("file.mp3"));
+
+        if let Value::Object(map) = json {
+            for (key, value) in map.into_iter() {
+                match value {
+                    Value::String(s) => {
+                        form = form.text(key, s);
+                    }
+                    Value::Number(n) => {
+                        form = form.text(key, n.to_string());
+                    }
+                    _ => {}
+                }
+            }
+        }
+
+        Ok(form)
+    }
 }
diff --git a/src/v1/assistant.rs b/src/v1/assistant.rs
index 0c18ffe..319073e 100644
--- a/src/v1/assistant.rs
+++ b/src/v1/assistant.rs
@@ -61,7 +61,6 @@ pub struct AssistantObject {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub tool_resources: Option<ToolResource>,
     pub metadata: Option<HashMap<String, String>>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone)]
@@ -101,14 +100,12 @@ pub struct DeletionStatus {
     pub id: String,
     pub object: String,
     pub deleted: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
 pub struct ListAssistant {
     pub object: String,
     pub data: Vec<AssistantObject>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize, Clone)]
@@ -122,12 +119,10 @@ pub struct AssistantFileObject {
     pub object: String,
     pub created_at: i64,
     pub assistant_id: String,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
 pub struct ListAssistantFile {
     pub object: String,
     pub data: Vec<AssistantFileObject>,
-    pub headers: Option<HashMap<String, String>>,
 }
diff --git a/src/v1/audio.rs b/src/v1/audio.rs
index b2c87f8..4ab93f4 100644
--- a/src/v1/audio.rs
+++ b/src/v1/audio.rs
@@ -1,6 +1,5 @@
 use reqwest::header::HeaderMap;
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
 
 use crate::impl_builder_methods;
 
@@ -8,9 +7,11 @@ pub const WHISPER_1: &str = "whisper-1";
 
 #[derive(Debug, Serialize, Clone)]
 pub struct AudioTranscriptionRequest {
-    pub file: String,
     pub model: String,
     #[serde(skip_serializing_if = "Option::is_none")]
+    pub file: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub bytes: Option<Vec<u8>>,
     pub prompt: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub response_format: Option<String>,
@@ -23,8 +24,21 @@ pub struct AudioTranscriptionRequest {
 impl AudioTranscriptionRequest {
     pub fn new(file: String, model: String) -> Self {
         Self {
-            file,
             model,
+            file: Some(file),
+            bytes: None,
+            prompt: None,
+            response_format: None,
+            temperature: None,
+            language: None,
+        }
+    }
+
+    pub fn new_bytes(bytes: Vec<u8>, model: String) -> Self {
+        Self {
+            model,
+            file: None,
+            bytes: Some(bytes),
             prompt: None,
             response_format: None,
             temperature: None,
@@ -44,7 +58,6 @@ impl_builder_methods!(
 #[derive(Debug, Deserialize, Serialize)]
 pub struct AudioTranscriptionResponse {
     pub text: String,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize, Clone)]
@@ -81,7 +94,6 @@ impl_builder_methods!(
 #[derive(Debug, Deserialize, Serialize)]
 pub struct AudioTranslationResponse {
     pub text: String,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 pub const TTS_1: &str = "tts-1";
diff --git a/src/v1/chat_completion.rs b/src/v1/chat_completion.rs
index aac6159..3849870 100644
--- a/src/v1/chat_completion.rs
+++ b/src/v1/chat_completion.rs
@@ -243,14 +243,13 @@ pub struct ChatCompletionChoice {
 
 #[derive(Debug, Deserialize, Serialize)]
 pub struct ChatCompletionResponse {
-    pub id: String,
+    pub id: Option<String>,
     pub object: String,
     pub created: i64,
     pub model: String,
     pub choices: Vec<ChatCompletionChoice>,
     pub usage: common::Usage,
     pub system_fingerprint: Option<String>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize, PartialEq, Eq)]
diff --git a/src/v1/common.rs b/src/v1/common.rs
index d641115..3fd5cf8 100644
--- a/src/v1/common.rs
+++ b/src/v1/common.rs
@@ -24,6 +24,10 @@ macro_rules! impl_builder_methods {
 #[derive(Debug, Serialize, Deserialize)]
 pub struct EmptyRequestBody {}
 
+// https://platform.openai.com/docs/models#gpt-4-5
+pub const GPT4_5_PREVIEW: &str = "gpt-4.5-preview";
+pub const GPT4_5_PREVIEW_2025_02_27: &str = "gpt-4.5-preview-2025-02-27";
+
 // https://platform.openai.com/docs/models/o1
 pub const O1_PREVIEW: &str = "o1-preview";
 pub const O1_PREVIEW_2024_09_12: &str = "o1-preview-2024-09-12";
diff --git a/src/v1/completion.rs b/src/v1/completion.rs
index c4d347f..a5adeaf 100644
--- a/src/v1/completion.rs
+++ b/src/v1/completion.rs
@@ -117,5 +117,4 @@ pub struct CompletionResponse {
     pub model: String,
     pub choices: Vec<CompletionChoice>,
     pub usage: common::Usage,
-    pub headers: Option<HashMap<String, String>>,
 }
diff --git a/src/v1/edit.rs b/src/v1/edit.rs
index c47ab01..18cf383 100644
--- a/src/v1/edit.rs
+++ b/src/v1/edit.rs
@@ -1,5 +1,4 @@
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
 use std::option::Option;
 
 use crate::impl_builder_methods;
@@ -52,5 +51,4 @@ pub struct EditResponse {
     pub created: i64,
     pub usage: common::Usage,
     pub choices: Vec<EditChoice>,
-    pub headers: Option<HashMap<String, String>>,
 }
diff --git a/src/v1/embedding.rs b/src/v1/embedding.rs
index a7305b0..3f68054 100644
--- a/src/v1/embedding.rs
+++ b/src/v1/embedding.rs
@@ -1,5 +1,4 @@
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
 use std::option::Option;
 
 use crate::impl_builder_methods;
@@ -52,7 +51,6 @@ pub struct EmbeddingResponse {
     pub data: Vec<EmbeddingData>,
     pub model: String,
     pub usage: Usage,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
diff --git a/src/v1/file.rs b/src/v1/file.rs
index d475a31..fceb4f8 100644
--- a/src/v1/file.rs
+++ b/src/v1/file.rs
@@ -1,5 +1,3 @@
-use std::collections::HashMap;
-
 use serde::{Deserialize, Serialize};
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -16,7 +14,6 @@ pub struct FileData {
 pub struct FileListResponse {
     pub object: String,
     pub data: Vec<FileData>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize)]
@@ -39,7 +36,6 @@ pub struct FileUploadResponse {
     pub created_at: i64,
     pub filename: String,
     pub purpose: String,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize)]
@@ -58,7 +54,6 @@ pub struct FileDeleteResponse {
     pub id: String,
     pub object: String,
     pub delete: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -69,5 +64,4 @@ pub struct FileRetrieveResponse {
     pub created_at: i64,
     pub filename: String,
     pub purpose: String,
-    pub headers: Option<HashMap<String, String>>,
 }
diff --git a/src/v1/fine_tuning.rs b/src/v1/fine_tuning.rs
index 8408a9d..8d696f9 100644
--- a/src/v1/fine_tuning.rs
+++ b/src/v1/fine_tuning.rs
@@ -1,5 +1,4 @@
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
 
 use crate::impl_builder_methods;
 
@@ -99,7 +98,6 @@ pub struct FineTuningPagination<T> {
     pub object: String,
     pub data: Vec<T>,
     pub has_more: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -118,7 +116,6 @@ pub struct FineTuningJobObject {
     pub trained_tokens: Option<i64>,
     pub training_file: String,
     pub validation_file: Option<String>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
diff --git a/src/v1/image.rs b/src/v1/image.rs
index 1963146..37038b0 100644
--- a/src/v1/image.rs
+++ b/src/v1/image.rs
@@ -1,5 +1,4 @@
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
 use std::option::Option;
 
 use crate::impl_builder_methods;
@@ -50,7 +49,6 @@ impl_builder_methods!(
 pub struct ImageGenerationResponse {
     pub created: i64,
     pub data: Vec<ImageData>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize, Clone)]
@@ -100,7 +98,6 @@ impl_builder_methods!(
 pub struct ImageEditResponse {
     pub created: i64,
     pub data: Vec<ImageData>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize, Clone)]
@@ -144,5 +141,4 @@ impl_builder_methods!(
 pub struct ImageVariationResponse {
     pub created: i64,
     pub data: Vec<ImageData>,
-    pub headers: Option<HashMap<String, String>>,
 }
diff --git a/src/v1/message.rs b/src/v1/message.rs
index 094689c..8ac7b66 100644
--- a/src/v1/message.rs
+++ b/src/v1/message.rs
@@ -68,7 +68,6 @@ pub struct MessageObject {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub attachments: Option<Vec<Attachment>>,
     pub metadata: Option<HashMap<String, String>>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -111,7 +110,6 @@ pub struct ListMessage {
     pub first_id: String,
     pub last_id: String,
     pub has_more: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -120,7 +118,6 @@ pub struct MessageFileObject {
     pub object: String,
     pub created_at: i64,
     pub message_id: String,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -130,7 +127,6 @@ pub struct ListMessageFile {
     pub first_id: String,
     pub last_id: String,
     pub has_more: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
diff --git a/src/v1/moderation.rs b/src/v1/moderation.rs
index b4989eb..69acece 100644
--- a/src/v1/moderation.rs
+++ b/src/v1/moderation.rs
@@ -1,5 +1,4 @@
 use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
 
 use crate::impl_builder_methods;
 
@@ -26,7 +25,6 @@ pub struct CreateModerationResponse {
     pub id: String,
     pub model: String,
     pub results: Vec<ModerationResult>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
diff --git a/src/v1/run.rs b/src/v1/run.rs
index 645104f..d084b62 100644
--- a/src/v1/run.rs
+++ b/src/v1/run.rs
@@ -98,7 +98,6 @@ pub struct RunObject {
     pub instructions: Option<String>,
     pub tools: Vec<types::Tools>,
     pub metadata: HashMap<String, String>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -108,7 +107,6 @@ pub struct ListRun {
     pub first_id: String,
     pub last_id: String,
     pub has_more: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Serialize, Clone)]
@@ -151,7 +149,6 @@ pub struct RunStepObject {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub completed_at: Option<i64>,
     pub metadata: HashMap<String, String>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone)]
@@ -161,5 +158,4 @@ pub struct ListRunStep {
     pub first_id: String,
     pub last_id: String,
     pub has_more: bool,
-    pub headers: Option<HashMap<String, String>>,
 }
diff --git a/src/v1/thread.rs b/src/v1/thread.rs
index 57e0b5c..73b1f5c 100644
--- a/src/v1/thread.rs
+++ b/src/v1/thread.rs
@@ -67,8 +67,6 @@ pub struct ThreadObject {
     pub metadata: HashMap<String, String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub tool_resources: Option<ToolResource>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone)]
@@ -86,7 +84,6 @@ pub struct Message {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub attachments: Option<Vec<Attachment>>,
     pub metadata: Option<HashMap<String, String>>,
-    pub headers: Option<HashMap<String, String>>,
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone)]