diff --git a/.gitmodules b/.gitmodules
index b68c6c73..413826f6 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -14,3 +14,7 @@
 	path = test
 	url = https://github.com/Interlisp/test
 	branch = master
+[submodule "online"]
+	path = online
+	url = https://github.com/Interlisp/online
+	branch = main
diff --git a/online b/online
new file mode 160000
index 00000000..9ae1f130
--- /dev/null
+++ b/online
@@ -0,0 +1 @@
+Subproject commit 9ae1f1308846608c41d402f3b5a44cd48c0286ef