diff --git a/README.md b/README.md
index 629687a..db356c4 100644
--- a/README.md
+++ b/README.md
@@ -94,6 +94,12 @@ org.freedesktop.tuhi1.Manager
 
       Read-only
 
+  Property: JSONDataVersions (au)
+      Specifies the JSON file format versions the server supports. The
+      client must request one of these versions in Device.GetJSONData().
+
+      Read-only, constant
+
   Method: StartSearch() -> ()
       Start searching for available devices ready for registering
       for an unspecified timeout. When the timeout expires or an error
@@ -295,14 +301,17 @@ org.freedesktop.tuhi1.Device
       arriving, the device may still send events. It's the responsibility of
       the client to handle events until the LiveStopped signal arrives.
 
-  Method: GetJSONData(timestamp: t) -> (s)
+  Method: GetJSONData(file-version: u, timestamp: t) -> (s)
       Returns a JSON file with the drawings specified by the timestamp
       argument. The requested timestamp must be one of the entries in the
-      DrawingsAvailable property value. See section JSON FILE
+      DrawingsAvailable property value. The file-version argument specifies
+      the file format version the client requests. See section JSON FILE
       FORMAT for the format of the returned data.
 
       Returns a string representing the JSON data from the last drawings or
-      the empty string if the timestamp is not available.
+      the empty string if the timestamp is not available or the file format
+      version is outside the server-supported range advertised in
+      Manager.JSONDataVersions.
 
   Signal: ButtonPressRequired()
       Sent when the user is expected to press the physical button on the
@@ -368,6 +377,12 @@ org.freedesktop.tuhi1.Device
 JSON File Format
 ----------------
 
+The current file format version is 1. A server may only support a subset of
+historical file formats, this subset is advertized as list of versions in
+the **org.freedesktop.tuhi1.Manager.JSONDataVersions** property. Likewise, a
+client may only support a subset of the possible formats. A client should
+always pick the highest format supported by both the client and the server.
+
 Below is the example file format (with comments, not present in the real
 files). The JSON objects are "drawing" (the root object), "strokes",
 "points".  Pseudo-code is used to illustrate the objects in the file.
diff --git a/tools/kete.py b/tools/kete.py
index 17d0fc2..4289737 100755
--- a/tools/kete.py
+++ b/tools/kete.py
@@ -271,7 +271,8 @@ class TuhiKeteDevice(_DBusObject):
         self.live = False
 
     def json(self, timestamp):
-        return self.proxy.GetJSONData('(t)', timestamp)
+        SUPPORTED_FILE_FORMAT = 1
+        return self.proxy.GetJSONData('(ut)', SUPPORTED_FILE_FORMAT, timestamp)
 
     def _on_signal_received(self, proxy, sender, signal, parameters):
         if signal == 'ButtonPressRequired':
diff --git a/tuhi/dbusserver.py b/tuhi/dbusserver.py
index afd6e4e..820868b 100755
--- a/tuhi/dbusserver.py
+++ b/tuhi/dbusserver.py
@@ -15,6 +15,7 @@ import logging
 import errno
 
 from gi.repository import GObject, Gio, GLib
+from .drawing import Drawing
 
 logger = logging.getLogger('tuhi.dbus')
 
@@ -29,6 +30,10 @@ INTROSPECTION_XML = '''
       <annotation name='org.freedesktop.DBus.Property.EmitsChangedSignal' value='true'/>
     </property>
 
+    <property type='au' name='JSONDataVersions' access='read'>
+      <annotation name='org.freedesktop.DBus.Property.EmitsChangedSignal' value='const'/>
+    </property>
+
     <method name='StartSearch'>
       <annotation name='org.freedesktop.DBus.Method.NoReply' value='true'/>
     </method>
@@ -87,6 +92,7 @@ INTROSPECTION_XML = '''
     </method>
 
     <method name='GetJSONData'>
+      <arg name='file_version' type='u' direction='in'/>
       <arg name='timestamp' type='t' direction='in'/>
       <arg name='json' type='s' direction='out'/>
     </method>
@@ -427,7 +433,12 @@ class TuhiDBusDevice(_TuhiDBus):
         self.live = False
 
     def _json_data(self, args):
-        index = args[0]
+        file_format = args[0]
+        if file_format != Drawing.JSON_FILE_FORMAT_VERSION:
+            logger.info(f'Unsupported file format requested: {file_format}')
+            return ''
+
+        index = args[1]
         try:
             drawing = self.drawings[index]
         except KeyError:
@@ -533,6 +544,9 @@ class TuhiDBusServer(_TuhiDBus):
             return GLib.Variant.new_objv([d.objpath for d in self._devices if d.registered])
         elif propname == 'Searching':
             return GLib.Variant.new_boolean(self.is_searching)
+        elif propname == 'JSONDataVersions':
+            return GLib.Variant.new_array(GLib.VariantType('u'),
+                                          [GLib.Variant.new_uint32(Drawing.JSON_FILE_FORMAT_VERSION)])
 
         return None