diff --git a/app/components/@settings/tabs/features/FeaturesTab.tsx b/app/components/@settings/tabs/features/FeaturesTab.tsx
index 3b14a7565d..11430be004 100644
--- a/app/components/@settings/tabs/features/FeaturesTab.tsx
+++ b/app/components/@settings/tabs/features/FeaturesTab.tsx
@@ -1,5 +1,5 @@
 // Remove unused imports
-import React, { memo, useCallback } from 'react';
+import React, { memo, useCallback, useState, useEffect } from 'react';
 import { motion } from 'framer-motion';
 import { Switch } from '~/components/ui/Switch';
 import { useSettings } from '~/lib/hooks/useSettings';
@@ -119,6 +119,29 @@ export default function FeaturesTab() {
     promptId,
   } = useSettings();
 
+  // State for custom prompt text
+  const [customPromptText, setCustomPromptText] = useState('');
+  const [hasUnsavedChanges, setHasUnsavedChanges] = useState(false);
+
+  // Load custom prompt from localStorage on component mount
+  useEffect(() => {
+    setCustomPromptText(PromptLibrary.getCustomPrompt());
+    setHasUnsavedChanges(false);
+  }, []);
+
+  // Handle custom prompt change
+  const handleCustomPromptChange = (e: React.ChangeEvent<HTMLTextAreaElement>) => {
+    setCustomPromptText(e.target.value);
+    setHasUnsavedChanges(true);
+  };
+
+  // Save custom prompt
+  const handleSaveCustomPrompt = () => {
+    PromptLibrary.saveCustomPrompt(customPromptText);
+    toast.success('Custom prompt saved');
+    setHasUnsavedChanges(false);
+  };
+
   // Enable features by default on first load
   React.useEffect(() => {
     // Only set defaults if values are undefined
@@ -143,6 +166,13 @@ export default function FeaturesTab() {
     }
   }, []); // Only run once on component mount
 
+  // Add this effect to check if the user has selected the custom prompt option but hasn't saved a custom prompt yet
+  useEffect(() => {
+    if (promptId === 'custom' && !PromptLibrary.hasCustomPrompt() && !customPromptText) {
+      toast.warning('Please create and save a custom prompt to use this option');
+    }
+  }, [promptId, customPromptText]);
+
   const handleToggleFeature = useCallback(
     (id: string, enabled: boolean) => {
       switch (id) {
@@ -177,6 +207,18 @@ export default function FeaturesTab() {
     [enableLatestBranch, setAutoSelectTemplate, enableContextOptimization, setEventLogs],
   );
 
+  // Update the select onChange handler to warn if selecting custom without a saved prompt
+  const handlePromptIdChange = (e: React.ChangeEvent<HTMLSelectElement>) => {
+    const newPromptId = e.target.value;
+
+    if (newPromptId === 'custom' && !PromptLibrary.hasCustomPrompt()) {
+      toast.info('Please create and save a custom prompt');
+    }
+
+    setPromptId(newPromptId);
+    toast.success('Prompt template updated');
+  };
+
   const features = {
     stable: [
       {
@@ -269,10 +311,7 @@ export default function FeaturesTab() {
           </div>
           <select
             value={promptId}
-            onChange={(e) => {
-              setPromptId(e.target.value);
-              toast.success('Prompt template updated');
-            }}
+            onChange={handlePromptIdChange}
             className={classNames(
               'p-2 rounded-lg text-sm min-w-[200px]',
               'bg-bolt-elements-background-depth-3 border border-bolt-elements-borderColor',
@@ -289,6 +328,48 @@ export default function FeaturesTab() {
             ))}
           </select>
         </div>
+
+        {/* Custom Prompt Text Area */}
+        {promptId === 'custom' && (
+          <motion.div
+            initial={{ opacity: 0, height: 0 }}
+            animate={{ opacity: 1, height: 'auto' }}
+            exit={{ opacity: 0, height: 0 }}
+            className="mt-4"
+          >
+            <textarea
+              value={customPromptText}
+              onChange={handleCustomPromptChange}
+              placeholder="Enter your custom system prompt here..."
+              className={classNames(
+                'w-full p-3 rounded-lg text-sm min-h-[200px]',
+                'bg-bolt-elements-background-depth-3 border border-bolt-elements-borderColor',
+                'text-bolt-elements-textPrimary',
+                'focus:outline-none focus:ring-2 focus:ring-purple-500/30',
+                'transition-all duration-200',
+                'resize-y',
+              )}
+            />
+            <div className="flex justify-between items-center mt-2">
+              <p className="text-xs text-bolt-elements-textSecondary">
+                {hasUnsavedChanges ? 'You have unsaved changes' : 'Your custom prompt is saved'}
+              </p>
+              <button
+                onClick={handleSaveCustomPrompt}
+                disabled={!hasUnsavedChanges}
+                className={classNames(
+                  'px-4 py-2 rounded-lg text-sm font-medium',
+                  'transition-all duration-200',
+                  hasUnsavedChanges
+                    ? 'bg-purple-500 text-white hover:bg-purple-600'
+                    : 'bg-bolt-elements-background-depth-4 text-bolt-elements-textTertiary cursor-not-allowed',
+                )}
+              >
+                Save Prompt
+              </button>
+            </div>
+          </motion.div>
+        )}
       </motion.div>
     </div>
   );
diff --git a/app/components/chat/Chat.client.tsx b/app/components/chat/Chat.client.tsx
index 8ac5d28626..96afff14d4 100644
--- a/app/components/chat/Chat.client.tsx
+++ b/app/components/chat/Chat.client.tsx
@@ -26,6 +26,7 @@ import { getTemplates, selectStarterTemplate } from '~/utils/selectStarterTempla
 import { logStore } from '~/lib/stores/logs';
 import { streamingState } from '~/lib/stores/streaming';
 import { filesToArtifacts } from '~/utils/fileUtils';
+import { CUSTOM_PROMPT_STORAGE_KEY } from '~/lib/common/prompt-library';
 
 const toastAnimation = cssTransition({
   enter: 'animated fadeInRight',
@@ -140,6 +141,36 @@ export const ChatImpl = memo(
 
     const [apiKeys, setApiKeys] = useState<Record<string, string>>({});
 
+    const [customPrompt, setCustomPrompt] = useState<string | undefined>(() => {
+      if (promptId === 'custom') {
+        return localStorage.getItem(CUSTOM_PROMPT_STORAGE_KEY) || undefined;
+      }
+
+      return undefined;
+    });
+
+    useEffect(() => {
+      if (promptId === 'custom') {
+        setCustomPrompt(localStorage.getItem(CUSTOM_PROMPT_STORAGE_KEY) || undefined);
+      } else {
+        setCustomPrompt(undefined);
+      }
+    }, [promptId]);
+
+    useEffect(() => {
+      const handleStorageChange = (event: StorageEvent) => {
+        if (event.key === CUSTOM_PROMPT_STORAGE_KEY && promptId === 'custom') {
+          setCustomPrompt(event.newValue || undefined);
+        }
+      };
+
+      window.addEventListener('storage', handleStorageChange);
+
+      return () => {
+        window.removeEventListener('storage', handleStorageChange);
+      };
+    }, [promptId]);
+
     const {
       messages,
       isLoading,
@@ -160,6 +191,7 @@ export const ChatImpl = memo(
         files,
         promptId,
         contextOptimization: contextOptimizationEnabled,
+        customPrompt,
       },
       sendExtraMessageFields: true,
       onError: (e) => {
diff --git a/app/lib/.server/llm/stream-text.ts b/app/lib/.server/llm/stream-text.ts
index 29579c9ff1..34af58cf3d 100644
--- a/app/lib/.server/llm/stream-text.ts
+++ b/app/lib/.server/llm/stream-text.ts
@@ -28,6 +28,7 @@ export async function streamText(props: {
   contextFiles?: FileMap;
   summary?: string;
   messageSliceId?: number;
+  customPrompt?: string;
 }) {
   const {
     messages,
@@ -40,6 +41,7 @@ export async function streamText(props: {
     contextOptimization,
     contextFiles,
     summary,
+    customPrompt,
   } = props;
   let currentModel = DEFAULT_MODEL;
   let currentProvider = DEFAULT_PROVIDER.name;
@@ -92,12 +94,29 @@ export async function streamText(props: {
 
   const dynamicMaxTokens = modelDetails && modelDetails.maxTokenAllowed ? modelDetails.maxTokenAllowed : MAX_TOKENS;
 
-  let systemPrompt =
-    PromptLibrary.getPropmtFromLibrary(promptId || 'default', {
-      cwd: WORK_DIR,
-      allowedHtmlElements: allowedHTMLElements,
-      modificationTagName: MODIFICATIONS_TAG_NAME,
-    }) ?? getSystemPrompt();
+  let systemPrompt;
+
+  if (promptId === 'custom') {
+    if (customPrompt && customPrompt.trim()) {
+      systemPrompt = customPrompt;
+    } else {
+      systemPrompt =
+        PromptLibrary.getPropmtFromLibrary('default', {
+          cwd: WORK_DIR,
+          allowedHtmlElements: allowedHTMLElements,
+          modificationTagName: MODIFICATIONS_TAG_NAME,
+        }) ?? getSystemPrompt();
+
+      logger.warn('Custom prompt selected but no custom prompt provided, falling back to default prompt');
+    }
+  } else {
+    systemPrompt =
+      PromptLibrary.getPropmtFromLibrary(promptId || 'default', {
+        cwd: WORK_DIR,
+        allowedHtmlElements: allowedHTMLElements,
+        modificationTagName: MODIFICATIONS_TAG_NAME,
+      }) ?? getSystemPrompt();
+  }
 
   if (files && contextFiles && contextOptimization) {
     const codeContext = createFilesContext(contextFiles, true);
diff --git a/app/lib/common/prompt-library.ts b/app/lib/common/prompt-library.ts
index 7513e81197..6759749a0f 100644
--- a/app/lib/common/prompt-library.ts
+++ b/app/lib/common/prompt-library.ts
@@ -7,6 +7,9 @@ export interface PromptOptions {
   modificationTagName: string;
 }
 
+// Define a constant for the localStorage key
+export const CUSTOM_PROMPT_STORAGE_KEY = 'custom_prompt';
+
 export class PromptLibrary {
   static library: Record<
     string,
@@ -26,6 +29,21 @@ export class PromptLibrary {
       description: 'an Experimental version of the prompt for lower token usage',
       get: (options) => optimized(options),
     },
+    custom: {
+      label: 'Custom Prompt',
+      description: 'Your own custom system prompt',
+      get: (_options) => {
+        // Get the custom prompt from localStorage if available
+        if (typeof window !== 'undefined') {
+          const customPrompt = localStorage.getItem(CUSTOM_PROMPT_STORAGE_KEY);
+          return customPrompt && customPrompt.trim()
+            ? customPrompt
+            : 'No custom prompt defined. Please set a custom prompt in the settings.';
+        }
+
+        return 'Custom prompt not available';
+      },
+    },
   };
   static getList() {
     return Object.entries(this.library).map(([key, value]) => {
@@ -41,9 +59,43 @@ export class PromptLibrary {
     const prompt = this.library[promptId];
 
     if (!prompt) {
-      throw 'Prompt Now Found';
+      throw 'Prompt Not Found';
     }
 
     return this.library[promptId]?.get(options);
   }
+
+  // Helper method to save a custom prompt to localStorage
+  static saveCustomPrompt(promptText: string): void {
+    if (typeof window !== 'undefined') {
+      localStorage.setItem(CUSTOM_PROMPT_STORAGE_KEY, promptText);
+
+      // Dispatch a storage event to notify other tabs/windows
+      window.dispatchEvent(
+        new StorageEvent('storage', {
+          key: CUSTOM_PROMPT_STORAGE_KEY,
+          newValue: promptText,
+        }),
+      );
+    }
+  }
+
+  // Helper method to get the current custom prompt from localStorage
+  static getCustomPrompt(): string {
+    if (typeof window !== 'undefined') {
+      return localStorage.getItem(CUSTOM_PROMPT_STORAGE_KEY) || '';
+    }
+
+    return '';
+  }
+
+  // Helper method to check if a custom prompt exists
+  static hasCustomPrompt(): boolean {
+    if (typeof window !== 'undefined') {
+      const prompt = localStorage.getItem(CUSTOM_PROMPT_STORAGE_KEY);
+      return !!prompt && prompt.trim().length > 0;
+    }
+
+    return false;
+  }
 }
diff --git a/app/routes/api.chat.ts b/app/routes/api.chat.ts
index bbecdae595..ccd26612d6 100644
--- a/app/routes/api.chat.ts
+++ b/app/routes/api.chat.ts
@@ -37,11 +37,12 @@ function parseCookies(cookieHeader: string): Record<string, string> {
 }
 
 async function chatAction({ context, request }: ActionFunctionArgs) {
-  const { messages, files, promptId, contextOptimization } = await request.json<{
+  const { messages, files, promptId, contextOptimization, customPrompt } = await request.json<{
     messages: Messages;
     files: any;
     promptId?: string;
     contextOptimization: boolean;
+    customPrompt?: string;
   }>();
 
   const cookieHeader = request.headers.get('Cookie');
@@ -242,6 +243,7 @@ async function chatAction({ context, request }: ActionFunctionArgs) {
               contextFiles: filteredFiles,
               summary,
               messageSliceId,
+              customPrompt,
             });
 
             result.mergeIntoDataStream(dataStream);
@@ -269,7 +271,7 @@ async function chatAction({ context, request }: ActionFunctionArgs) {
           message: 'Generating Response',
         } satisfies ProgressAnnotation);
 
-        const result = await streamText({
+        const textStream = await streamText({
           messages,
           env: context.cloudflare?.env,
           options,
@@ -281,10 +283,11 @@ async function chatAction({ context, request }: ActionFunctionArgs) {
           contextFiles: filteredFiles,
           summary,
           messageSliceId,
+          customPrompt,
         });
 
         (async () => {
-          for await (const part of result.fullStream) {
+          for await (const part of textStream.fullStream) {
             if (part.type === 'error') {
               const error: any = part.error;
               logger.error(`${error}`);
@@ -293,7 +296,7 @@ async function chatAction({ context, request }: ActionFunctionArgs) {
             }
           }
         })();
-        result.mergeIntoDataStream(dataStream);
+        textStream.mergeIntoDataStream(dataStream);
       },
       onError: (error: any) => `Custom error: ${error.message}`,
     }).pipeThrough(