diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index 73e3a74b..23520466 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -1790,6 +1790,14 @@
     "message": "If checked, the Model will think before answering. This option works only with models that support the 'think' feature.",
     "description": ""
   },
+  "prefs_ollama_format_json": {
+    "message": "Force JSON output",
+    "description": ""
+  },
+  "prefs_ollama_format_json_Info": {
+    "message": "If checked, Ollama will be forced to return a valid JSON response. This option works only with models that support structured output.",
+    "description": ""
+  },
   "chatgpt_win_change_reply_type": {
     "message": "Click to change the reply type",
     "description": ""
diff --git a/claude-spec/04-api-integrations.md b/claude-spec/04-api-integrations.md
index 318eadbf..d4ef33e6 100644
--- a/claude-spec/04-api-integrations.md
+++ b/claude-spec/04-api-integrations.md
@@ -32,7 +32,7 @@ Content script `js/lib/diff.js` is injected into ChatGPT pages for diff-view sup
 ### Ollama (`ollama_api`)
 - Module: `js/api/ollama.js`
 - Worker: `js/workers/model-worker-ollama.js`
-- Settings keys: `ollama_host`, `ollama_model`, `ollama_num_ctx`, `ollama_temperature`, `ollama_think`
+- Settings keys: `ollama_host`, `ollama_model`, `ollama_num_ctx`, `ollama_temperature`, `ollama_think`, `ollama_format_json`
 - Requires CORS to be configured on the Ollama server
 
 ### OpenAI-Compatible (`openai_comp_api`)
diff --git a/js/api/ollama.js b/js/api/ollama.js
index 07d5a066..32433dda 100644
--- a/js/api/ollama.js
+++ b/js/api/ollama.js
@@ -24,7 +24,8 @@ export class Ollama {
     num_ctx = 0;
     temperature = '';
     think = false;
-  
+    format_json = false;
+
     constructor({
       host = '',
       model = '',
@@ -32,6 +33,7 @@ export class Ollama {
       num_ctx = 0,
       temperature = '',
       think = false,
+      format_json = false,
     } = {}) {
       this.host = (host || '').trim().replace(/\/+$/, "");
       this.model = model;
@@ -39,6 +41,7 @@ export class Ollama {
       this.num_ctx = num_ctx;
       this.temperature = temperature;
       this.think = think;
+      this.format_json = format_json;
     }
 
     fetchModels = async () => {
@@ -93,6 +96,7 @@ export class Ollama {
                 messages: messages,
                 stream: this.stream,
                 think: this.think,
+                ...(this.format_json ? { format: "json" } : {}),
                 ...(this.num_ctx > 0 ? { options: { num_ctx: parseInt(this.num_ctx) } } : {}),
                 ...(this.temperature != '' && !Number.isNaN(tempFloat) ? { options: { temperature: tempFloat } } : {}),
             }),
diff --git a/options/mzta-options-default.js b/options/mzta-options-default.js
index 4ac38c96..8776c8b6 100644
--- a/options/mzta-options-default.js
+++ b/options/mzta-options-default.js
@@ -31,7 +31,8 @@ export const integration_options_config = {
         model: '',
         num_ctx: 0,
         temperature: '',
-        think: false
+        think: false,
+        format_json: false
     },
     openai_comp: {
         host: '',
diff --git a/pages/_lib/connection-ui.js b/pages/_lib/connection-ui.js
index 64a0d0eb..5ff56863 100644
--- a/pages/_lib/connection-ui.js
+++ b/pages/_lib/connection-ui.js
@@ -358,6 +358,17 @@ export async function injectConnectionUI({
       </label>
     </td>
   </tr>
+  <tr class="conntype_ollama_api${tr_class ? ` ${tr_class}` : ''}">
+    <td><label>
+      <span class="opt_title">__MSG_prefs_ollama_format_json__</span>
+    </label></td>
+    <td>
+      <label>
+        <input type="checkbox" id="${modelId_prefix ? `${modelId_prefix}` : ''}ollama_format_json" name="${modelId_prefix ? `${modelId_prefix}` : ''}ollama_format_json" class="option-input"/>
+        __MSG_prefs_ollama_format_json_Info__
+      </label>
+    </td>
+  </tr>
   <tr class="conntype_ollama_api${tr_class ? ` ${tr_class}` : ''}">
     <td><label>
       <span class="opt_title">__MSG_prefs_ollama_num_ctx__ <i>[num_ctx]</i></span>
@@ -571,20 +582,20 @@ export async function injectConnectionUI({
   }
 
   conntype_select.addEventListener("change", () => showConnectionOptions(conntype_select));
-  conntype_select.addEventListener("change", (ev) => warn_ChatGPT_APIKeyEmpty(modelId_prefix));
-  conntype_select.addEventListener("change", (ev) => warn_Ollama_HostEmpty(modelId_prefix));
-  conntype_select.addEventListener("change", (ev) => warn_OpenAIComp_HostEmpty(modelId_prefix));
-  conntype_select.addEventListener("change", (ev) => warn_GoogleGemini_APIKeyEmpty(modelId_prefix));
-  conntype_select.addEventListener("change", (ev) => warn_Anthropic_APIKeyEmpty(modelId_prefix));
-  conntype_select.addEventListener("change", (ev) => warn_Anthropic_VersionEmpty(modelId_prefix));
+  conntype_select.addEventListener("change", () => warn_ChatGPT_APIKeyEmpty(modelId_prefix));
+  conntype_select.addEventListener("change", () => warn_Ollama_HostEmpty(modelId_prefix));
+  conntype_select.addEventListener("change", () => warn_OpenAIComp_HostEmpty(modelId_prefix));
+  conntype_select.addEventListener("change", () => warn_GoogleGemini_APIKeyEmpty(modelId_prefix));
+  conntype_select.addEventListener("change", () => warn_Anthropic_APIKeyEmpty(modelId_prefix));
+  conntype_select.addEventListener("change", () => warn_Anthropic_VersionEmpty(modelId_prefix));
   document.getElementById("chatgpt_web_project").addEventListener("input", validateCustomData_ChatGPTWeb);
   document.getElementById("chatgpt_web_custom_gpt").addEventListener("input", validateCustomData_ChatGPTWeb);
-  document.getElementById(getPrefixedId("chatgpt_api_key")).addEventListener("change", (ev) => warn_ChatGPT_APIKeyEmpty(modelId_prefix));
-  document.getElementById(getPrefixedId("ollama_host")).addEventListener("change", (ev) => warn_Ollama_HostEmpty(modelId_prefix));
-  document.getElementById(getPrefixedId("openai_comp_host")).addEventListener("change", (ev) => warn_OpenAIComp_HostEmpty(modelId_prefix));
-  document.getElementById(getPrefixedId("google_gemini_api_key")).addEventListener("change", (ev) => warn_GoogleGemini_APIKeyEmpty(modelId_prefix));
-  document.getElementById(getPrefixedId("anthropic_api_key")).addEventListener("change", (ev) => warn_Anthropic_APIKeyEmpty(modelId_prefix));
-  document.getElementById(getPrefixedId("anthropic_version")).addEventListener("change", (ev) => warn_Anthropic_VersionEmpty(modelId_prefix));
+  document.getElementById(getPrefixedId("chatgpt_api_key")).addEventListener("change", () => warn_ChatGPT_APIKeyEmpty(modelId_prefix));
+  document.getElementById(getPrefixedId("ollama_host")).addEventListener("change", () => warn_Ollama_HostEmpty(modelId_prefix));
+  document.getElementById(getPrefixedId("openai_comp_host")).addEventListener("change", () => warn_OpenAIComp_HostEmpty(modelId_prefix));
+  document.getElementById(getPrefixedId("google_gemini_api_key")).addEventListener("change", () => warn_GoogleGemini_APIKeyEmpty(modelId_prefix));
+  document.getElementById(getPrefixedId("anthropic_api_key")).addEventListener("change", () => warn_Anthropic_APIKeyEmpty(modelId_prefix));
+  document.getElementById(getPrefixedId("anthropic_version")).addEventListener("change", () => warn_Anthropic_VersionEmpty(modelId_prefix));
   document.getElementById(getPrefixedId("openai_comp_host")).addEventListener("input", () => resetOpenAICompConfigs(modelId_prefix));
   document.getElementById(getPrefixedId("openai_comp_chat_name")).addEventListener("input", () => resetOpenAICompConfigs(modelId_prefix));
   document.getElementById(getPrefixedId("openai_comp_use_v1")).addEventListener("input", () => resetOpenAICompConfigs(modelId_prefix));