diff --git a/docs/index.md b/docs/index.md
index 5d046a66e7d..440590d075f 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -45,3 +45,4 @@
 * [Settings management](settings.md)
 * [Internal Signaling API](internal-signaling.md)
 * [Standalone Signaling API](https://nextcloud-spreed-signaling.readthedocs.io/en/latest/)
+* [Signaling Messages](signaling-messages.md)
diff --git a/docs/internal-signaling.md b/docs/internal-signaling.md
index 000cb7c31c6..0622be57a46 100644
--- a/docs/internal-signaling.md
+++ b/docs/internal-signaling.md
@@ -54,3 +54,7 @@ Todo
 ### External signaling API
 
 See [External signaling API](https://nextcloud-spreed-signaling.readthedocs.io/en/latest/) for the Signaling API of the High-Performance Backend.
+
+### Signaling messages
+
+See [Signaling Messages](signaling-messages.md)
diff --git a/docs/signaling-messages.md b/docs/signaling-messages.md
new file mode 100644
index 00000000000..131512b817e
--- /dev/null
+++ b/docs/signaling-messages.md
@@ -0,0 +1,381 @@
+# Signaling messages
+
+This contains the schema of signaling messages used in Nextcloud Talk.
+
+## General
+
+### Sender property (external signaling)
+
+```
+{
+    sessionid = #STRING#,
+    type = #STRING#,
+    userid = #STRING,
+}
+```
+
+## Offer
+
+### External signaling
+
+| field           | type    | Description                        |
+|-----------------|---------|------------------------------------|
+| `roomType`      | string  | "video" or "screen"                |
+| `sid`           | string  | external signaling server >= 0.5.0 |
+
+```
+{
+    "type": "message",
+    "message": {
+        "sender": {
+            ...
+        },
+        "data": {
+            "to": #STRING#,
+            "from":  #STRING#,
+            "type": "offer",
+            "roomType": #STRING#,
+            "payload": {
+                "type": "offer",
+                "sdp": #STRING#,
+            },
+            "sid": #STRING#,
+        },
+    },
+}
+```
+
+### Internal signaling
+
+| field           | type    | Description           |
+|-----------------|---------|-----------------------|
+| `roomType`      | string  | "video" or "screen"   |
+| `nick`          | string  | optional              |
+
+```
+{
+    "type": "message",
+    "data": {
+        "to": #STRING#,
+        "sid": #STRING#,
+        "roomType": #STRING#,
+        "type": "offer",
+        "payload": {
+            "type": "offer",
+            "sdp": #STRING#,
+            "nick": #STRING#,
+        },
+        "from": #STRING#,
+    },
+}
+```
+
+## Candidate
+
+### External signaling
+
+| field      | type   | Description                        |
+| ---------- | ------ | ---------------------------------- |
+| `roomType` | string | "video" or "screen"                |
+| `sid`      | string | external signaling server >= 0.5.0 |
+
+```
+{
+    "type": "message",
+    "message": {
+        "sender": {
+            ...
+        },
+        "data": {
+            "to": #STRING#,
+            "from":  #STRING#,
+            "type": "candidate",
+            "roomType": #STRING#,
+            "payload": {
+                "candidate": {
+                    "candidate": #STRING#,
+                    "sdpMid": #STRING#,
+                    "sdpMLineIndex": #INTEGER#,
+                },
+            },
+            "sid": #STRING#,
+        },
+    },
+}
+```
+
+### Internal signaling
+
+| field      | type   | Description                        |
+| ---------- | ------ | ---------------------------------- |
+| `roomType` | string | "video" or "screen"                |
+
+```
+{
+    "type": "message",
+    "data": {
+        "to": #STRING#,
+        "sid": #STRING#,
+        "roomType": #STRING#,
+        "type": "candidate",
+        "payload": {
+            "candidate": {
+                "candidate": #STRING#,
+                "sdpMid": #STRING#,
+                "sdpMLineIndex": #INTEGER#,
+            },
+        },
+        "from": #STRING#,
+    },
+}
+```
+
+## Update all participants
+
+External signaling only
+
+| field    | type    | Description        |
+| -------- | ------- | ------------------ |
+| `roomid` | string  | conversation token |
+
+```
+{
+    "type": "event",
+    "event": {
+        "target": "participants",
+        "type": "update",
+        "update": {
+            "roomid": #STRING#,
+            "incall": 0,
+            "all": true,
+        },
+    },
+}
+```
+
+## Update participants
+
+External signaling only
+
+| field                    | type    | Description        |
+| ------------------------ | ------- | ------------------ |
+| `roomid`                 | string  | conversation token |
+| `userId`                 | string  | optional           |
+| `nextcloudSessionId`     | string  | optional           |
+| `internal`               | boolean | optional           |
+| `participantPermissions` | integer | Talk >= 13         |
+
+Note that `userId` in participants->update comes from the Nextcloud server, so it is `userId`; in other messages, like room->join, it comes directly from the external signaling server, so it is `userid` instead.
+
+ ```
+{
+    "type": "event",
+    "event": {
+        "target": "participants",
+        "type": "update",
+        "update": {
+            "roomid": #STRING#,
+            "users": [
+                {
+                    "inCall": #INTEGER#,
+                    "lastPing": #INTEGER#,
+                    "sessionId": #STRING#,
+                    "participantType": #INTEGER#,
+                    "userId": #STRING#,
+                    "nextcloudSessionId": #STRING#,
+                    "internal": #BOOLEAN#,
+                    "participantPermissions": #INTEGER#,
+                },
+                ...
+            ],
+        },
+    },
+}
+```
+
+## Users in room
+
+Internal signaling only
+
+| field                    | type    | Description                               |
+| ------------------------ | ------- | ----------------------------------------- |
+| `roomId`                 | integer | Internal room id (not conversation token) |
+| `userId`                 | string  | Always included, although it can be empty |
+| `participantPermissions` | integer | Talk >= 13                                |
+
+```
+{
+    "type": "usersInRoom",
+    "data": [
+        {
+            "inCall": #INTEGER#,
+            "lastPing": #INTEGER#,
+            "roomId": #INTEGER#,
+            "sessionId": #STRING#,
+            "userId": #STRING#,
+            "participantPermissions": #INTEGER#,
+        },
+        ...
+    ],
+}
+```
+
+## Raise hand
+
+Needs `raise-hand` capability
+
+| field                    | type    | Description                       |
+| ------------------------ | ------- | --------------------------------- |
+| `state`                  | boolean | 0 - hand lowered; 1 - hand raised |
+
+### External signaling
+
+```
+{
+    "type": "message",
+    "message": {
+        "sender": {
+            ...
+        },
+        "data": {
+            "to": #STRING#,
+            "sid": #STRING#,
+            "roomType": "video",
+            "type": "raiseHand",
+            "payload": {
+                "state": #BOOLEAN#,
+                "timestamp": #LONG#,
+            },
+            "from": #STRING#,
+        },
+    },
+}
+```
+
+### Internal signaling
+
+```
+{
+    "type": "message",
+    "data": {
+        "to": #STRING#,
+        "sid": #STRING#,
+        "roomType": "video",
+        "type": "raiseHand",
+        "payload": {
+            "state": #BOOLEAN#,
+            "timestamp": #LONG#,
+        },
+        "from": #STRING#,
+    },
+}
+```
+
+## Unshare screen
+
+### External signaling
+
+```
+{
+    "type": "message",
+    "message": {
+        "sender": {
+            ...
+        },
+        "data": {
+            "roomType": "screen",
+            "type": "unshareScreen",
+            "from": #STRING#,
+        },
+    },
+}
+```
+
+### Internal signaling
+
+```
+{
+    "type": "message",
+    "data": {
+        "to": #STRING#,
+        "sid": #STRING#,
+        "broadcaster": #STRING#,
+        "roomType": "screen",
+        "type": "unshareScreen",
+        "from": #STRING#,
+    },
+}
+```
+
+## Switchto
+
+External signaling only
+
+Needs `breakout-rooms-v1` capability and external signaling server >= 1.1.0
+
+| field    | type    | Description        |
+| -------- | ------- | ------------------ |
+| `roomid` | string  | conversation token |
+
+```
+{
+    "type": "event",
+    "event": {
+        "target": "room",
+        "type": "switchto",
+        "switchto": {
+            "roomid": #STRING#,
+        },
+    },
+}
+```
+
+## Call reactions
+
+### External signaling
+
+| field      | type   | Description                               |
+| ---------- | ------ | ----------------------------------------- |
+| `roomType` | string | "video" or "screen"                       |
+| `reaction` | string | Single emoji which is shown as a reaction |
+| `sid`      | string | external signaling server >= 0.5.0        |
+
+```
+{
+    "type": "message",
+    "message": {
+        "sender": {
+            ...
+        },
+        "data": {
+            "to": #STRING#,
+            "sid": #STRING#,
+            "roomType": #STRING#,
+            "type": "reaction",
+            "payload" :{
+                "reaction": #STRING#
+            }
+        }
+    }
+}
+```
+
+### Internal signaling
+
+| field      | type   | Description                               |
+| ---------- | ------ | ----------------------------------------- |
+| `roomType` | string | "video" or "screen"                       |
+| `reaction` | string | Single emoji which is shown as a reaction |
+
+```
+{
+    "to": #STRING#,
+    "sid": #STRING#,
+    "roomType": #STRING#,
+    "type": "reaction",
+    "payload": {
+        "reaction": #STRING#
+    },
+    "from": #STRING#
+}
+```