As announced on zotero-dev, version 2 of the Zotero Web API brings many changes to enable API-based syncing. While read-only clients may continue to work properly, clients that write to the API are likely to need updating.

This page provides a brief summary of changes and may not be comprehensive. See the appropriate documentation sections for full details on all changes.

• New: API versioning
• New: Conditional read support
• New: Multi-object modification and multi-object deletion
• New: Delta writes
• Saved search metadata is now available via the API. It is not currently possible to retrieve the results of saved searches via the API.
• Related items and relations are now available in the relations property of item JSON. Currently, only the RDF predicates used by Zotero itself are available.
• Object ETags have been replaced by library/object versions. If-Match has been replaced by If-Unmodified-Since-Version and JSON version properties.
• Object writes no longer return Atom feeds with the newly created objects. Single-object writes return 204 No Content, while multi-object writes return 200 OK with a JSON document indicating the status of each write.
• X-Zotero-Write-Token has changed to Zotero-Write-Token.
• Child items can no longer be created by including note or attachment properties when creating top-level items or by POSTing to <userOrGroupPrefix>/items/<itemKey>/children. Instead, child items can be created or moved by including a parentItem property in the item's JSON.
• New collection JSON objects can no longer be POSTed directly. Instead, collections must be within a top-level collections object, similar to the items object used for items.
• The parent property for collections has been changed to parentCollection.
• The collections an item belongs to can be read and modified via the item's collections property. The previous POST and DELETE requests have been removed.