diff --git a/raillabel/json_format/stream_sync.py b/raillabel/json_format/stream_sync.py
new file mode 100644
index 0000000..0be704c
--- /dev/null
+++ b/raillabel/json_format/stream_sync.py
@@ -0,0 +1,27 @@
+# Copyright DB InfraGO AG and contributors
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+from decimal import Decimal
+
+from pydantic import BaseModel
+
+
+class JSONStreamSync(BaseModel):
+    """Syncronization information of a stream in a frame."""
+
+    stream_properties: JSONStreamSyncProperties
+    uri: str | None
+
+
+class JSONStreamSyncProperties(BaseModel):
+    """The sync information."""
+
+    sync: JSONStreamSyncTimestamp
+
+
+class JSONStreamSyncTimestamp(BaseModel):
+    """The timestamp of a stream sync."""
+
+    timestamp: Decimal | str