diff --git a/config/config.js b/config/config.js
index 5666176..2a5d8c1 100644
--- a/config/config.js
+++ b/config/config.js
@@ -4,6 +4,7 @@ const dev = {
     apiEndpoint: 'https://apitest.authorize.net/rest/v1',
     apiLoginId: process.env.apiLogin || 'your api login id',
     transactionKey: process.env.transactionKey || 'your transaction key',
+    webhookSecret: process.env.WEBHOOK_SECRET || 'your-webhook-secret-key',
     app: {
         port: parseInt(process.env.PORT) || 9000,
         host: process.env.APP_DB_HOST || '0.0.0.0'
@@ -26,6 +27,7 @@ const test = {
     apiEndpoint: 'https://apitest.authorize.net/rest/v1',
     apiLoginId: process.env.apiLogin || 'your api login id',
     transactionKey: process.env.transactionKey || 'your transaction key',
+    webhookSecret: process.env.WEBHOOK_SECRET || 'your-webhook-secret-key',
     app: {
         port: parseInt(process.env.PORT) || 9000,
         host: process.env.APP_DB_HOST || '0.0.0.0'
diff --git a/public/javascripts/index.js b/public/javascripts/index.js
index 9438bad..f675412 100644
--- a/public/javascripts/index.js
+++ b/public/javascripts/index.js
@@ -2,6 +2,21 @@
 // Initialize socket variable
 var socket = io(), maxNotificationCount;
 
+/**
+ * Escapes HTML special characters to prevent XSS attacks
+ * @param {string} str - The string to escape
+ * @returns {string} The escaped string
+ */
+function escapeHtml(str) {
+    if (str == null) return '';
+    return String(str)
+        .replace(/&/g, '&')
+        .replace(/</g, '&lt;')
+        .replace(/>/g, '&gt;')
+        .replace(/"/g, '&quot;')
+        .replace(/'/g, '&#39;');
+}
+
 /**
  * Triggered when an item is dropdown is selected.
  * Makes current panel content empty
@@ -176,12 +191,17 @@ function displayEventMessage(eventDetails) {
     var formatedPayload = JSON.stringify(eventDetails, null,"\t")
                            .slice(1,-1);
 
+    // Escape all user-controlled data to prevent XSS attacks
+    var safeEventDate = escapeHtml(eventDate);
+    var safeEventType = escapeHtml(eventDetails.eventType);
+    var safeFormatedPayload = escapeHtml(formatedPayload);
+
     newPanel.innerHTML =
         `<div class="row event-headings" style="background-color: lavender;height: 100px">
-            <div class="col-xs-2">${eventDate}</div>
-            <div class="col-xs-5" style="padding: 0px;text-align: center;word-break: break-all">${eventDetails.eventType}</div>
+            <div class="col-xs-2">${safeEventDate}</div>
+            <div class="col-xs-5" style="padding: 0px;text-align: center;word-break: break-all">${safeEventType}</div>
             <div class="col-xs-5" style="padding: 0px;">
-                <pre style="background-color: palegoldenrod;padding: 0px;margin: 0px auto;height: 100px">${formatedPayload}</pre>
+                <pre style="background-color: palegoldenrod;padding: 0px;margin: 0px auto;height: 100px">${safeFormatedPayload}</pre>
             </div>
         </div>`;
 
diff --git a/server.js b/server.js
index edb41fb..7c573a0 100644
--- a/server.js
+++ b/server.js
@@ -14,6 +14,7 @@ const csurf = require('csurf');
 const cookieParser = require("cookie-parser");
 var csp = require("helmet-csp");
 var fs = require("fs");
+var crypto = require("crypto");
 
 app.use(bodyParser.json());
 app.use(express.static(path.join(__dirname, 'public')));
@@ -23,7 +24,7 @@ app.use(csp({
   // Specify directives as normal.
   directives: {
     defaultSrc: ["'self'"],
-    scriptSrc: ["'self'", "'unsafe-inline'"],
+    scriptSrc: ["'self'"],
     styleSrc: ["'self'", "'unsafe-inline'"],
     fontSrc:["'self'"],
     imgSrc: ["'self'"],
@@ -78,16 +79,53 @@ io.on('connection', function(){
     });
 });
 
+/**
+ * Verifies the HMAC signature of incoming webhook requests
+ * @param {string} payload - The raw request body
+ * @param {string} signature - The signature from the request header
+ * @returns {boolean} - True if signature is valid, false otherwise
+ */
+function verifyWebhookSignature(payload, signature) {
+    if (!signature || !config.webhookSecret) {
+        return false;
+    }
+    const expectedSignature = crypto
+        .createHmac('sha256', config.webhookSecret)
+        .update(payload)
+        .digest('hex');
+    // Use timing-safe comparison to prevent timing attacks
+    try {
+        return crypto.timingSafeEqual(
+            Buffer.from(signature),
+            Buffer.from(expectedSignature)
+        );
+    } catch (err) {
+        return false;
+    }
+}
+
 // Handles POST message to "/notifications" endpoint. Updates notifications set, inserts
 // new notification, emit a new event to be captured by front end code
-app.post("/notifications", async function (req, res) {
+app.post("/notifications", express.text({ type: '*/*' }), async function (req, res) {
     try {
+        // Verify webhook signature (HMAC)
+        const signature = req.get('X-ANET-Signature') || req.get('X-Webhook-Signature');
+        const rawBody = typeof req.body === 'string' ? req.body : JSON.stringify(req.body);
+        
+        if (!verifyWebhookSignature(rawBody, signature)) {
+            console.error('Webhook signature verification failed');
+            return res.status(401).json({ error: 'Invalid webhook signature' });
+        }
+
+        // Parse body if it was received as text
+        const body = typeof req.body === 'string' ? JSON.parse(req.body) : req.body;
+
         io.emit("newNotification", {
-            eventDetails: (req.body),
+            eventDetails: body,
         });
         var notifications = await updateNotifications();
 
-        notifications = await insertNewNotification(notifications, req.body);
+        notifications = await insertNewNotification(notifications, body);
 
         res.sendStatus(201);
     }catch(err) {