try:
             conn, site, params = self._init_handling()
             if 'calendar' == site:
-                html = self.do_GET_calendar(conn)
+                start = params.get('start', [''])[0]
+                end = params.get('end', [''])[0]
+                html = self.do_GET_calendar(conn, start, end)
             elif 'day' == site:
                 date = params.get('date', [todays_date()])[0]
                 html = self.do_GET_day(conn, date)
         except HandledException as error:
             self._send_msg(error)
 
-    def do_GET_calendar(self, conn: DatabaseConnection):
+    def do_GET_calendar(self, conn: DatabaseConnection, start: str, end: str):
         """Show Days."""
         return self.server.jinja.get_template('calendar.html').render(
-                days=Day.all(conn))
+                days=Day.all(conn, date_range=(start, end)))
 
     def do_GET_day(self, conn: DatabaseConnection, date: str):
         """Show single Day."""
 
         self.assertEqual(http_conn.getresponse().status, 400)
         http_conn.request('GET', '/calendar')
         self.assertEqual(http_conn.getresponse().status, 200)
+        http_conn.request('GET', '/calendar?start=&end=')
+        self.assertEqual(http_conn.getresponse().status, 200)
+        http_conn.request('GET', '/calendar?start=today&end=today')
+        self.assertEqual(http_conn.getresponse().status, 200)
+        http_conn.request('GET', '/calendar?start=2024-01-01&end=2025-01-01')
+        self.assertEqual(http_conn.getresponse().status, 200)
+        http_conn.request('GET', '/calendar?start=foo')
+        self.assertEqual(http_conn.getresponse().status, 400)
 
     def tearDown(self):
         self.httpd.shutdown()