A client device can be configured to perform a local index search and a server index search to automatically identify and upload content items on the client device that have not been uploaded to an online content management system. A local index search can include creating a unique local identifier of a content item and searching a local upload index that includes the unique local identifier of each content item that has been uploaded. A server index search can include creating a unique server identifier of the content item and searching a server upload index that includes the unique server identifier of each content item stored on the online content management system. Content items that are determined to have not been uploaded to the online content management system based on the results of the two searches, can be uploaded to the content management system by the client device.