diff --git a/README.md b/README.md
index 603dfc4..a113d96 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,50 @@
 # room-rs
 
+# Message format
+
+Enter room:
+```json
+{
+  "type": "Enter",
+  "roomId": "<roomid>",
+  "clientId": "<clientid>"
+}
+```
+
+Exit room:
+```json
+{
+  "type": "Exit"
+}
+```
+
+Destroy room:
+```json
+{
+  "type": "Destroy"
+}
+```
+
+List room peers:
+```json
+{
+  "type": "ListPeers"
+}
+```
+
+Broadcast room message:
+```json
+{
+  "type": "Broadcast",
+  "data": "<message>"
+}
+```
+
+Send room peer message:
+```json
+{
+  "type": "Peer",
+  "peerId": "<peerclientid>",
+  "data": "<message>"
+}
+```
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