diff --git a/api_webchat/controller.js b/api_webchat/controller.js
index d4a9cc52..5f29526a 100644
--- a/api_webchat/controller.js
+++ b/api_webchat/controller.js
@@ -49,7 +49,7 @@ let worker = null;
 
 switch (llm) {
     case "chatgpt_api":
-        worker = new Worker('../js/workers/model-worker-openai.js', { type: 'module' });
+        worker = new Worker('../js/workers/model-worker-openai_responses.js', { type: 'module' });
         break;
     case "google_gemini_api":
         worker = new Worker('../js/workers/model-worker-google_gemini.js', { type: 'module' });
diff --git a/js/api/openai_responses.js b/js/api/openai_responses.js
new file mode 100644
index 00000000..9066132e
--- /dev/null
+++ b/js/api/openai_responses.js
@@ -0,0 +1,111 @@
+/*
+ *  ThunderAI [https://micz.it/thunderbird-addon-thunderai/]
+ *  Copyright (C) 2024 - 2025  Mic (m@micz.it)
+
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// Some original methods derived from https://github.com/ali-raheem/Aify/blob/4ece286095ea7a6cf89d696902e6b81b5d1c3a4b/plugin/html/API.js
+
+
+export class OpenAI {
+
+  apiKey = '';
+  model = '';
+  developer_messages = '';
+  stream = false;
+  store = false;
+
+  constructor(apiKey, model, developer_messages, stream, store) {
+    this.apiKey = apiKey;
+    this.model = model;
+    this.developer_messages = developer_messages;
+    this.stream = stream;
+    this.store = store;
+  }
+
+
+  fetchModels = async () => {
+    try{
+      const response = await fetch("https://api.openai.com/v1/models", {
+          method: "GET",
+          headers: {
+              "Content-Type": "application/json",
+              Authorization: "Bearer "+ this.apiKey
+          },
+      });
+
+      if (!response.ok) {
+          const errorDetail = await response.text();
+          let err_msg = "[ThunderAI] OpenAI API request failed: " + response.status + " " + response.statusText + ", Detail: " + errorDetail;
+          console.error(err_msg);
+          let output = {};
+          output.ok = false;
+          output.error = errorDetail;
+          return output;
+      }
+
+      let output = {};
+      output.ok = true;
+      let output_response = await response.json();
+      output.response = output_response.data.filter(item => item.id.startsWith('gpt-')).sort((a, b) => b.id.localeCompare(a.id));
+
+      return output;
+    }catch (error) {
+      console.error("[ThunderAI] OpenAI API request failed: " + error);
+      let output = {};
+      output.is_exception = true;
+      output.ok = false;
+      output.error = "OpenAI API request failed: " + error;
+      return output;
+    }
+  }
+
+  fetchResponse = async (messages, maxTokens = 0) => {
+
+    let request_body = { 
+              model: this.model, 
+              input: messages,
+              stream: this.stream,
+              store: this.store,
+              ...(maxTokens > 0 ? { 'max_tokens': parseInt(maxTokens) } : {})
+          }
+
+    if(this.developer_messages !== ''){
+       request_body.instructions = this.developer_messages;
+    }
+
+    // console.log(">>>>>>>>>>> OpenAI API request: " + JSON.stringify(messages));
+
+    try {
+      const response = await fetch("https://api.openai.com/v1/responses", {
+          method: "POST",
+          headers: { 
+              "Content-Type": "application/json", 
+              Authorization: "Bearer "+ this.apiKey
+          },
+          body: JSON.stringify(request_body),
+      });
+      return response;
+    }catch (error) {
+        console.error("[ThunderAI] OpenAI Responses API request failed: " + error);
+        let output = {};
+        output.is_exception = true;
+        output.ok = false;
+        output.error = "OpenAI Responses API request failed: " + error;
+        return output;
+    }
+  }
+
+}
\ No newline at end of file
diff --git a/js/mzta-special-commands.js b/js/mzta-special-commands.js
index 0bbab812..a6ddaad3 100644
--- a/js/mzta-special-commands.js
+++ b/js/mzta-special-commands.js
@@ -44,7 +44,7 @@
         this.do_debug = do_debug;
         switch (this.llm) {
             case "chatgpt_api":
-                this.worker = new Worker(new URL('./workers/model-worker-openai.js', import.meta.url), { type: 'module' });
+                this.worker = new Worker(new URL('./workers/model-worker-openai_responses.js', import.meta.url), { type: 'module' });
                 break;
             case "google_gemini_api":
                 this.worker = new Worker(new URL('./workers/model-worker-google_gemini.js', import.meta.url), { type: 'module' });
diff --git a/js/workers/model-worker-openai_responses.js b/js/workers/model-worker-openai_responses.js
new file mode 100644
index 00000000..2e58e08b
--- /dev/null
+++ b/js/workers/model-worker-openai_responses.js
@@ -0,0 +1,124 @@
+/*
+ *  ThunderAI [https://micz.it/thunderbird-addon-thunderai/]
+ *  Copyright (C) 2024 - 2025  Mic (m@micz.it)
+
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * 
+ * 
+ *  This file contains a modified version of the code from the project at https://github.com/boxabirds/chatgpt-frontend-nobuild
+ *  The original code has been released under the Apache License, Version 2.0.
+ */
+
+import { OpenAI } from '../api/openai_responses.js';
+import { taLogger } from '../mzta-logger.js';
+
+let chatgpt_api_key = null;
+let chatgpt_model = '';
+let openai = null;
+let stopStreaming = false;
+let i18nStrings = null;
+let do_debug = false;
+let taLog = null
+
+let conversationHistory = [];
+let assistantResponseAccumulator = '';
+let previous_response_id = -1;
+
+self.onmessage = async function(event) {
+    if (event.data.type === 'init') {
+        chatgpt_api_key = event.data.chatgpt_api_key;
+        chatgpt_model = event.data.chatgpt_model;
+        openai = new OpenAI(chatgpt_api_key, chatgpt_model, event.data.chatgpt_developer_messages, true, event.data.chatgpt_api_store);
+        do_debug = event.data.do_debug;
+        i18nStrings = event.data.i18nStrings;
+        taLog = new taLogger('model-worker-openai_responses', do_debug);
+    } else if (event.data.type === 'chatMessage') {
+        conversationHistory.push({ role: 'user', content: event.data.message });
+
+    const response = await openai.fetchResponse(conversationHistory); //4096);
+        postMessage({ type: 'messageSent' });
+
+        if (!response.ok) {
+            let error_message = '';
+            let errorDetail = '';
+            if(response.is_exception === true){
+                error_message = response.error;
+            }else{
+                try{
+                    const errorJSON = await response.json();
+                    errorDetail = JSON.stringify(errorJSON);
+                    error_message = errorJSON.error.message;
+                }catch(e){
+                    error_message = response.statusText;
+                }
+                taLog.log("error_message: " + JSON.stringify(error_message));
+            }
+            postMessage({ type: 'error', payload: i18nStrings["chatgpt_api_request_failed"] + ": " + response.status + " " + response.statusText + ", Detail: " + error_message + " " + errorDetail });
+            throw new Error("[ThunderAI] OpenAI ChatGPT API request failed: " + response.status + " " + response.statusText + ", Detail: " + error_message + " " + errorDetail);
+        }
+
+        const reader = response.body.getReader();
+        const decoder = new TextDecoder("utf-8");
+        let buffer = '';
+    
+        while (true) {
+            if (stopStreaming) {
+                stopStreaming = false;
+                reader.cancel();
+                conversationHistory.push({ role: 'assistant', content: assistantResponseAccumulator });
+                assistantResponseAccumulator = '';
+                postMessage({ type: 'tokensDone' });
+                break;
+            }
+            const { done, value } = await reader.read();
+            if (done) {
+                conversationHistory.push({ role: 'assistant', content: assistantResponseAccumulator });
+                assistantResponseAccumulator = '';
+                postMessage({ type: 'tokensDone' });
+                break;
+            }
+            // lots of low-level OpenAI response parsing stuff
+            const chunk = decoder.decode(value);
+            buffer += chunk;
+            taLog.log("buffer " + buffer);
+            const lines = buffer.split("\n");
+            buffer = lines.pop();
+            let parsedLines = [];
+            try{
+                parsedLines = lines
+                    .map((line) => line.replace(/^data: /, "").trim()) // Remove the "data: " prefix
+                    .filter((line) => line !== "" && line !== "[DONE]") // Remove empty lines and "[DONE]"
+                    // .map((line) => JSON.parse(line)); // Parse the JSON string
+                    .map((line) => {
+                        taLog.log("line: " + JSON.stringify(line));
+                        return JSON.parse(line);
+                    });
+            }catch(e){
+                taLog.error("Error parsing lines: " + e);
+            }
+    
+            for (const parsedLine of parsedLines) {
+                console.log(">>>>>>>>>> parsedLine: " + JSON.stringify(parsedLine));
+                const { content } = parsedLine;
+                // Update the UI with the new content
+                if (content) {
+                    assistantResponseAccumulator += content;
+                    postMessage({ type: 'newToken', payload: { token: content } });
+                }
+            }
+        }
+    } else if (event.data.type === 'stop') {
+        stopStreaming = true;
+    }
+};