diff --git a/lib/storage/blogs.js b/lib/storage/blogs.js
index 33f7a99..e5ebac4 100644
--- a/lib/storage/blogs.js
+++ b/lib/storage/blogs.js
@@ -86,7 +86,7 @@ export async function getBlogByFeedUrl(application, feedUrl) {
  */
 export async function createBlog(application, data) {
   const collection = getCollection(application);
-  const now = new Date();
+  const now = new Date().toISOString();
 
   const blog = {
     sourceId: data.sourceId ? new ObjectId(data.sourceId) : null,
@@ -127,7 +127,7 @@ export async function updateBlog(application, id, data) {
 
   const update = {
     ...data,
-    updatedAt: new Date(),
+    updatedAt: new Date().toISOString(),
   };
 
   // Remove fields that shouldn't be updated directly
@@ -162,8 +162,8 @@ export async function deleteBlog(application, id) {
       $set: {
         status: "deleted",
         hidden: true,
-        deletedAt: new Date(),
-        updatedAt: new Date(),
+        deletedAt: new Date().toISOString(),
+        updatedAt: new Date().toISOString(),
       },
     }
   );
@@ -181,12 +181,12 @@ export async function updateBlogStatus(application, id, status) {
   const objectId = typeof id === "string" ? new ObjectId(id) : id;
 
   const update = {
-    updatedAt: new Date(),
+    updatedAt: new Date().toISOString(),
   };
 
   if (status.success) {
     update.status = "active";
-    update.lastFetchAt = new Date();
+    update.lastFetchAt = new Date().toISOString();
     update.lastError = null;
     if (status.itemCount !== undefined) {
       update.itemCount = status.itemCount;
@@ -246,7 +246,7 @@ export async function getCategories(application) {
  */
 export async function upsertBlog(application, data) {
   const collection = getCollection(application);
-  const now = new Date();
+  const now = new Date().toISOString();
 
   // Skip if a blog with this feedUrl was soft-deleted
   const deleted = await collection.findOne({
diff --git a/lib/storage/items.js b/lib/storage/items.js
index 9e66101..0519b4b 100644
--- a/lib/storage/items.js
+++ b/lib/storage/items.js
@@ -206,7 +206,7 @@ export async function countItems(application, options = {}) {
  */
 export async function upsertItem(application, data) {
   const collection = getCollection(application);
-  const now = new Date();
+  const now = new Date().toISOString();
 
   const result = await collection.updateOne(
     { blogId: new ObjectId(data.blogId), uid: data.uid },
diff --git a/lib/storage/sources.js b/lib/storage/sources.js
index 6a01572..465fb3c 100644
--- a/lib/storage/sources.js
+++ b/lib/storage/sources.js
@@ -45,7 +45,7 @@ export async function getSource(application, id) {
  */
 export async function createSource(application, data) {
   const collection = getCollection(application);
-  const now = new Date();
+  const now = new Date().toISOString();
 
   const source = {
     type: data.type, // "opml_url" | "opml_file" | "manual" | "json_feed" | "microsub"
@@ -80,7 +80,7 @@ export async function updateSource(application, id, data) {
 
   const update = {
     ...data,
-    updatedAt: new Date(),
+    updatedAt: new Date().toISOString(),
   };
 
   // Remove fields that shouldn't be updated directly
@@ -135,11 +135,11 @@ export async function updateSourceSyncStatus(application, id, status) {
   const objectId = typeof id === "string" ? new ObjectId(id) : id;
 
   const update = {
-    updatedAt: new Date(),
+    updatedAt: new Date().toISOString(),
   };
 
   if (status.success) {
-    update.lastSyncAt = new Date();
+    update.lastSyncAt = new Date().toISOString();
     update.lastSyncError = null;
   } else {
     update.lastSyncError = status.error;
diff --git a/lib/sync/feed.js b/lib/sync/feed.js
index a6e4084..b7803cc 100644
--- a/lib/sync/feed.js
+++ b/lib/sync/feed.js
@@ -142,8 +142,8 @@ function parseJsonFeed(content, feedUrl, maxItems) {
       text: item.content_text,
     },
     summary: decodeEntities(item.summary) || truncateText(item.content_text, 300),
-    published: item.date_published ? new Date(item.date_published) : new Date(),
-    updated: item.date_modified ? new Date(item.date_modified) : undefined,
+    published: item.date_published ? new Date(item.date_published).toISOString() : new Date().toISOString(),
+    updated: item.date_modified ? new Date(item.date_modified).toISOString() : undefined,
     author: item.author || (item.authors?.[0]),
     photo: item.image ? [item.image] : undefined,
     categories: item.tags || [],
@@ -168,6 +168,10 @@ function parseJsonFeed(content, feedUrl, maxItems) {
 function normalizeItem(item, feedUrl) {
   const description = item.description || item.summary || "";
 
+  // Convert dates to ISO strings - feedparser returns Date objects
+  const published = item.pubdate || item.date;
+  const updated = item.date;
+
   return {
     uid: generateUid(feedUrl, item.guid || item.link),
     url: item.link || item.origlink,
@@ -177,8 +181,8 @@ function normalizeItem(item, feedUrl) {
       text: stripHtml(description),
     },
     summary: truncateText(stripHtml(item.summary || description), 300),
-    published: item.pubdate || item.date || new Date(),
-    updated: item.date,
+    published: published ? (published instanceof Date ? published.toISOString() : new Date(published).toISOString()) : new Date().toISOString(),
+    updated: updated ? (updated instanceof Date ? updated.toISOString() : new Date(updated).toISOString()) : undefined,
     author: item.author ? { name: item.author } : undefined,
     photo: extractPhotos(item),
     categories: item.categories || [],
diff --git a/lib/sync/microsub.js b/lib/sync/microsub.js
index 890b747..8c0e606 100644
--- a/lib/sync/microsub.js
+++ b/lib/sync/microsub.js
@@ -100,8 +100,8 @@ export async function syncMicrosubSource(application, source) {
           $set: {
             status: "deleted",
             hidden: true,
-            deletedAt: new Date(),
-            updatedAt: new Date(),
+            deletedAt: new Date().toISOString(),
+            updatedAt: new Date().toISOString(),
           },
         }
       );
@@ -227,8 +227,8 @@ export async function handleMicrosubWebhook(application, data) {
         {
           $set: {
             status: "inactive",
-            unsubscribedAt: new Date(),
-            updatedAt: new Date(),
+            unsubscribedAt: new Date().toISOString(),
+            updatedAt: new Date().toISOString(),
           },
         }
       );
diff --git a/lib/sync/scheduler.js b/lib/sync/scheduler.js
index a320e73..d499f72 100644
--- a/lib/sync/scheduler.js
+++ b/lib/sync/scheduler.js
@@ -110,7 +110,7 @@ export async function runFullSync(application, options = {}) {
       {
         $set: {
           key: "syncStats",
-          lastFullSync: new Date(),
+          lastFullSync: new Date().toISOString(),
           duration,
           sources: {
             total: enabledSources.length,
diff --git a/package.json b/package.json
index de3b18b..d818e64 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-blogroll",
-  "version": "1.0.16",
+  "version": "1.0.17",
   "description": "Blogroll endpoint for Indiekit. Aggregates blog feeds from OPML, JSON feeds, or manual entry.",
   "keywords": [
     "indiekit",