diff --git a/src/pyj/srv.pyj b/src/pyj/srv.pyj
index e0d60f1b3c..8ee9a8bba2 100644
--- a/src/pyj/srv.pyj
+++ b/src/pyj/srv.pyj
@@ -1,6 +1,6 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-# globals: ρσ_get_module
+# globals: ρσ_get_module, self
 from __python__ import hash_literals
 
 import initialize  # noqa: unused-import
@@ -13,6 +13,15 @@ autoreload_enabled = False
 AUTO_UPDATE_THRESHOLD = 1000  # millisecs
 
 
+def worker_main(entry_point):
+    m = ρσ_get_module(window.iframe_entry_point)
+    main = m?.main
+    if main:
+        main()
+    else:
+        console.log('worker entry_point ' + entry_point + ' not found')
+
+
 def iframe_main(script):
     script.parentNode.removeChild(script)  # free up some memory
     script = undefined
@@ -58,3 +67,8 @@ if document?:
         iframe_main(iframe_script)
     else:
         toplevel_main()
+        url = window.URL.createObjectURL(Blob([main_js()]), {'type': 'text/javascript'})
+        worker = new window.Worker(url + '#moo')
+        console.log(worker)
+elif self?:
+    entry_point = self.location.hash[1:]
diff --git a/src/pyj/worker.pyj b/src/pyj/worker.pyj
new file mode 100644
index 0000000000..2c81ea297c
--- /dev/null
+++ b/src/pyj/worker.pyj
@@ -0,0 +1,15 @@
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2021, Kovid Goyal <kovid at kovidgoyal.net>
+from __python__ import bound_methods, hash_literals
+
+from book_list.globals import main_js
+
+
+def worker_js_url(entry_point):
+    if not worker_js_url.ans:
+        worker_js_url.ans = window.URL.createObjectURL(Blob([main_js()]), {'type': 'text/javascript'})
+    return worker_js_url.ans + '#' + entry_point
+
+
+def start_worker(entry_point):
+    return new window.Worker(worker_js_url(entry_point))