diff --git a/README.md b/README.md
index 592266a..ff20c96 100644
--- a/README.md
+++ b/README.md
@@ -61,4 +61,12 @@ Send room peer message:
   "peerId": "<peerclientid>",
   "data": "<message>"
 }
+```
+
+Test with command line:
+> WebSocket cat: https://www.npmjs.com/package/wscat
+
+Install `wscat` with `npm`:
+```shell
+npm install -g wscat
 ```
\ No newline at end of file