diff --git a/README.md b/README.md
index c9f93bc..309ab14 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,11 @@ your PC.
 Standard library only: no `pip install`, no virtualenv, nothing to keep
 patched beyond Python itself.
 
+**Which apps it serves.** PassMan for Windows 2.x and PassMan for Linux
+0.x sync with it. The PassMan 3 test versions (Windows 3.0.0-alpha, Linux
+1.0.0-alpha) do not sync yet: they need accounts on the server, which come
+with server 2.0.
+
 This repository is the server for **Linux**, run by systemd. The other
 parts of PassMan have their own repositories: