There are two standard alternatives for JSON patch format that can be used data exchanged in synchronization process:

JSON Patch: https://tools.ietf.org/html/rfc6902
JSON Merge Patch: https://tools.ietf.org/html/draft-ietf-appsawg-json-merge-patch

The exchange of JSON patches would allow clients to update data in tree-like data structures such as object graphs (trees) or JavaScript objects.