diff --git a/appengine/expiration.py b/appengine/expiration.py
new file mode 100644
index 000000000..19142c30a
--- /dev/null
+++ b/appengine/expiration.py
@@ -0,0 +1,51 @@
+"""
+Copyright 2020 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+"""Delete expired XML.
+"""
+
+__author__ = "fenichel@google.com (Rachel Fenichel)"
+
+
+import storage
+import datetime
+
+from google.cloud import ndb
+
+
+EXPIRATION_DAYS = 365
+# Limit the query to avoid timeouts.
+QUERY_LIMIT = 1000
+
+def delete_expired():
+  """Deletes entries that have not been accessed in more than a year."""
+  bestBefore = datetime.datetime.utcnow() - datetime.timedelta(days=EXPIRATION_DAYS)
+  client = ndb.Client()
+  with client.context():
+    query = storage.Xml.query(storage.Xml.last_accessed < bestBefore)
+    results = query.fetch(limit=QUERY_LIMIT, keys_only=True)
+    for x in results:
+      x.delete()
+
+
+def app(environ, start_response):
+  out = ""
+  headers = [
+    ("Content-Type", "text/plain")
+  ]
+  start_response("200 OK", headers)
+  delete_expired()
+  return [out.encode("utf-8")]
diff --git a/appengine/main.py b/appengine/main.py
index 349c4f0c1..765087c61 100644
--- a/appengine/main.py
+++ b/appengine/main.py
@@ -15,6 +15,7 @@ limitations under the License.
 """
 
 import storage
+import expiration
 
 
 # Route to requested handler.
@@ -23,6 +24,8 @@ def app(environ, start_response):
     return redirect(environ, start_response)
   if environ["PATH_INFO"] == "/storage":
     return storage.app(environ, start_response)
+  if environ["PATH_INFO"] == "/expiration":
+    return expiration.app(environ, start_response)
   start_response("404 Not Found", [])
   return [b"Page not found."]