You can use :ref:`Data Ingest <optimize-data-ingest>` to stream data from the client application to a Flexible Sync-enabled Atlas App Services App.
You might want to sync data unidirectionally in IoT applications, such as a weather sensor sending data to the cloud. Data Ingest is also useful for writing other types of immutable data where you do not require conflict resolution, such as creating invoices from a retail app or logging application events.
Data Ingest is optimized to provide performance improvements for heavy client-side insert-only workloads.