diff --git a/.changeset/quiet-masks-fetch.md b/.changeset/quiet-masks-fetch.md
new file mode 100644
index 000000000..94d449412
--- /dev/null
+++ b/.changeset/quiet-masks-fetch.md
@@ -0,0 +1,5 @@
+---
+'@shopify/shopify-app-express': minor
+---
+
+Fixes OPTIONS object inside authenticated session middleware
diff --git a/packages/api-clients/storefront-api-client/README.md b/packages/api-clients/storefront-api-client/README.md
index 92730e2a5..eb4034f98 100644
--- a/packages/api-clients/storefront-api-client/README.md
+++ b/packages/api-clients/storefront-api-client/README.md
@@ -20,7 +20,7 @@ pnpm add @shopify/storefront-api-client
 
 ### CDN
 
-The UMD builds of each release version are available via the [`unpkg` CDN](https://unpkg.com/browse/@shopify/storefront-api-client@latest/dist/umd/)
+The UMD builds of each release version are available via the [`unpkg` CDN](https://unpkg.com/browse/@shopify/storefront-api-client@latest/dist/umd/) 
 
 ```html
 // The minified `0.2.3` version of the Storefront API Client
diff --git a/packages/apps/shopify-app-express/src/middlewares/validate-authenticated-session.ts b/packages/apps/shopify-app-express/src/middlewares/validate-authenticated-session.ts
index 6d4746c32..952d9476c 100644
--- a/packages/apps/shopify-app-express/src/middlewares/validate-authenticated-session.ts
+++ b/packages/apps/shopify-app-express/src/middlewares/validate-authenticated-session.ts
@@ -10,6 +10,21 @@ import {hasValidAccessToken} from './has-valid-access-token';
 
 interface validateAuthenticatedSessionParams extends ApiAndConfigParams {}
 
+/**
+ * Middleware to validate the session for authenticated requests.
+ *
+ * This middleware ensures that the incoming request has a valid session,
+ * and it checks if the session has an active and valid access token.
+ *
+ * If the session is invalid, it redirects the user to the authentication flow.
+ *
+ * Additionally, this middleware handles preflight `OPTIONS` requests for CORS
+ * by bypassing the authentication checks and responding with the appropriate
+ * CORS headers.
+ *
+ * @param {validateAuthenticatedSessionParams} params - The parameters required for the middleware, including the API and config.
+ * @returns {ValidateAuthenticatedSessionMiddleware} The middleware function that validates the session.
+ */
 export function validateAuthenticatedSession({
   api,
   config,
@@ -18,6 +33,22 @@ export function validateAuthenticatedSession({
     return async (req: Request, res: Response, next: NextFunction) => {
       config.logger.info('Running validateAuthenticatedSession');
 
+      // Handle preflight OPTIONS requests for CORS
+      // Bypasses authentication and responds with the necessary CORS headers.
+      if (req.method === 'OPTIONS') {
+        res.header('Access-Control-Allow-Origin', '*');
+        res.header(
+          'Access-Control-Allow-Methods',
+          'GET,POST,PUT,DELETE,OPTIONS',
+        );
+        res.header(
+          'Access-Control-Allow-Headers',
+          'Content-Type, Authorization',
+        );
+        // Respond with 200 OK for OPTIONS requests
+        return res.sendStatus(200);
+      }
+
       let sessionId: string | undefined;
       try {
         sessionId = await api.session.getCurrentId({
@@ -29,7 +60,6 @@ export function validateAuthenticatedSession({
         config.logger.error(
           `Error when loading session from storage: ${error}`,
         );
-
         handleSessionError(req, res, error);
         return undefined;
       }
@@ -42,9 +72,7 @@ export function validateAuthenticatedSession({
           config.logger.error(
             `Error when loading session from storage: ${error}`,
           );
-
-          res.status(500);
-          res.send(error.message);
+          res.status(500).send(error.message);
           return undefined;
         }
       }
@@ -52,15 +80,20 @@ export function validateAuthenticatedSession({
       let shop =
         api.utils.sanitizeShop(req.query.shop as string) || session?.shop;
 
+      // Check if the session is associated with the same shop as the request
       if (session && shop && session.shop !== shop) {
         config.logger.debug(
           'Found a session for a different shop in the request',
-          {currentShop: session.shop, requestShop: shop},
+          {
+            currentShop: session.shop,
+            requestShop: shop,
+          },
         );
 
         return redirectToAuth({req, res, api, config});
       }
 
+      // Validate if the session is active and has a valid access token
       if (session) {
         config.logger.debug('Request session found and loaded', {
           shop: session.shop,
@@ -76,6 +109,7 @@ export function validateAuthenticatedSession({
               shop: session.shop,
             });
 
+            // Attach the session to the response's locals for further use
             res.locals.shopify = {
               ...res.locals.shopify,
               session,
@@ -85,6 +119,7 @@ export function validateAuthenticatedSession({
         }
       }
 
+      // Handle Bearer token in Authorization header for API requests
       const bearerPresent = req.headers.authorization?.match(/Bearer (.*)/);
       if (bearerPresent) {
         if (!shop) {
@@ -96,6 +131,7 @@ export function validateAuthenticatedSession({
         }
       }
 
+      // Redirect to the authentication flow if the session is not valid
       const redirectUri = `${config.auth.path}?shop=${shop}`;
       config.logger.info(
         `Session was not valid. Redirecting to ${redirectUri}`,
@@ -112,19 +148,32 @@ export function validateAuthenticatedSession({
   };
 }
 
+/**
+ * Handles session errors by sending the appropriate response to the client.
+ *
+ * @param {Request} _req - The Express request object.
+ * @param {Response} res - The Express response object.
+ * @param {Error} error - The error encountered while handling the session.
+ */
 function handleSessionError(_req: Request, res: Response, error: Error) {
   switch (true) {
     case error instanceof InvalidJwtError:
-      res.status(401);
-      res.send(error.message);
+      res.status(401).send(error.message);
       break;
     default:
-      res.status(500);
-      res.send(error.message);
+      res.status(500).send(error.message);
       break;
   }
 }
 
+/**
+ * Sets the shop value from the session or token for API requests.
+ *
+ * @param {Shopify} api - The Shopify API instance.
+ * @param {Session | undefined} session - The session object.
+ * @param {string} token - The Bearer token from the Authorization header.
+ * @returns {Promise<string | undefined>} The shop domain if available.
+ */
 async function setShopFromSessionOrToken(
   api: Shopify,
   session: Session | undefined,