diff --git a/web/js/auto-formatter.js b/web/js/auto-formatter.js
new file mode 100644
index 0000000..3229501
--- /dev/null
+++ b/web/js/auto-formatter.js
@@ -0,0 +1,98 @@
+import { settingValues } from './settings.js';
+
+/**
+ * Event handler for auto-formatting functionality
+ */
+export class AutoFormatterEventHandler {
+    constructor() {}
+
+    /**
+     * Handle blur event to trigger auto-formatting
+     * @param {Event} event - The blur event
+     */
+    handleBlur(event) {
+        if (
+            settingValues.enableAutoFormat &&
+            event.target.tagName === 'TEXTAREA'
+        ) {
+            formatTextareaOnBlur(event.target);
+        }
+    }
+
+    // Placeholder methods to maintain consistency with other event handlers
+    handleInput(event) {}
+    handleFocus(event) {}
+    handleKeyDown(event) {}
+    handleKeyUp(event) {}
+    handleMouseMove(event) {}
+    handleClick(event) {}
+}
+
+/**
+ * Format the prompt text: add a comma and space after each tag, and remove extra spaces.
+ * Preserve special syntax such as weights (tag:1.2), parentheses, and wildcards.
+ * @param {string} text - The original text.
+ * @returns {string} - The formatted text.
+ */
+export function formatPromptText(text) {
+    if (!text || text.trim().length === 0) return text;
+
+    // Split text into individual lines for processing
+    const lines = text.split('\n');
+    const formattedLines = [];
+
+    for (const line of lines) {
+        const trimmedLine = line.trim();
+
+        // Keep empty lines unchanged
+        if (trimmedLine.length === 0) {
+            formattedLines.push('');
+            continue;
+        }
+
+        // Split the line by commas into raw tag segments
+        const rawTags = trimmedLine.split(',');
+
+        const cleanedTags = [];
+        for (const tag of rawTags) {
+            // Trim spaces around each tag
+            const trimmedTag = tag.trim();
+
+            // Keep only non-empty tags
+            if (trimmedTag.length > 0) {
+                cleanedTags.push(trimmedTag);
+            }
+        }
+
+        // Rejoin cleaned tags with ", "
+        let formattedLine = cleanedTags.join(', ');
+
+        // Add a trailing comma and space if the line contains valid tags
+        if (formattedLine.length > 0) {
+            formattedLine += ', ';
+        }
+
+        formattedLines.push(formattedLine);
+    }
+
+    // Rejoin all lines with newline characters
+    return formattedLines.join('\n');
+}
+
+/**
+ * Format the content of a textarea when it loses focus.
+ * @param {HTMLTextAreaElement} textarea - The target textarea element.
+ */
+export function formatTextareaOnBlur(textarea) {
+    const originalText = textarea.value;
+    const formattedText = formatPromptText(originalText);
+
+    if (originalText !== formattedText) {
+        const cursorPos = textarea.selectionStart;
+        textarea.value = formattedText;
+
+        // Try to preserve cursor position
+        const newCursorPos = Math.min(cursorPos, formattedText.length);
+        textarea.setSelectionRange(newCursorPos, newCursorPos);
+    }
+}
diff --git a/web/js/main.js b/web/js/main.js
index 9facef4..e6e3836 100644
--- a/web/js/main.js
+++ b/web/js/main.js
@@ -6,6 +6,7 @@ import { loadCSS } from "./utils.js";
 import { TagSource, loadDataAsync } from "./data.js";
 import { AutocompleteEventHandler } from "./autocomplete.js";
 import { RelatedTagsEventHandler } from "./related-tags.js";
+import { AutoFormatterEventHandler } from "./auto-formatter.js";
 
 // --- Constants ---
 const id = "AutocompletePlus";
@@ -18,6 +19,7 @@ const name = "Autocomplete Plus";
 function initializeEventHandlers() {
     const autocompleteEventHandler = new AutocompleteEventHandler();
     const relatedTagsEventHandler = new RelatedTagsEventHandler();
+    const autoFormatterEventHandler = new AutoFormatterEventHandler();
     const attachedElements = new WeakSet(); // Keep track of elements that have listeners attached
 
     // Function to attach listeners
@@ -105,6 +107,7 @@ function initializeEventHandlers() {
     function handleBlur(event) {
         autocompleteEventHandler.handleBlur(event);
         relatedTagsEventHandler.handleBlur(event);
+        autoFormatterEventHandler.handleBlur(event);
     }
 
     function handleKeyDown(event) {
@@ -416,5 +419,17 @@ app.registerExtension({
                 settingValues.hideAlias = newVal;
             }
         },
+
+        // --- Auto format settings ---
+        {
+            id: id + '.AutoFormatter.EnableAutoFormat',
+            name: 'Enable Auto Format',
+            type: 'boolean',
+            defaultValue: true,
+            category: [name, 'AutoFormatter', 'Enable Auto Format'],
+            onChange: (newVal, oldVal) => {
+                settingValues.enableAutoFormat = newVal;
+            },
+        },
     ]
 });
\ No newline at end of file
diff --git a/web/js/settings.js b/web/js/settings.js
index 1e12424..177b620 100644
--- a/web/js/settings.js
+++ b/web/js/settings.js
@@ -21,6 +21,9 @@ export const settingValues = {
     // Display settings
     hideAlias: false, // Hide alias in the autocomplete and related tags display
 
+    // Auto format settings
+    enableAutoFormat: true,
+
 
     // Internal logic settings
     _useFallbackAttachmentForEventListener: false, // Fallback to attach event listener when somthing goes wrong