Zotero Server Read Requests

This is version 2 of the Zotero Web API. For new development, use API version 3.

The page documents read requests available in the Zotero Web API, providing read-only access to online Zotero libraries.

The base URL for all API requests is

https://api.zotero.org

All requests must use HTTPS rather than HTTP.

To use this version of the API, include the HTTP header Zotero-API-Version: 2 with all requests. The current default version is version 3.

At most times, there is only one active API version, and changes are made in a backwards-compatible manner. On rare occasions, however, backwards-incompatible changes may need to be made. When this occurs, the new API version will first be made available via an HTTP header, Zotero-API-Version: <version>, while all other clients continue to receive the old version. After a transition period, the new API version will become the default. At that point, the previous API version may be discontinued, with the new API version being returned even to clients requesting the previous version. Announcements regarding API version transitions will always be made ahead of time on zotero-dev.

The API version of a response will be returned in the Zotero-API-Version response header.

Accessing non-public data via the API requires use of an API key. Third-party developers should use OAuth to establish credentials or instruct their users to create dedicated keys for use with their services. End users can create API keys via their Zotero account settings.

Requests for data in a specific library begin with /users/<userID> or /groups/<groupID>. User IDs are different from usernames and can be found on the API Keys page and in OAuth responses.

All parameters are optional.

itemType and tag parameters support Boolean searches:

Examples:

• “itemType=book”
• “itemType=book || journalArticle” (OR)
• “itemType=-attachment” (NOT)

• “tag=foo”
• “tag=foo bar” (tag with space)
• “tag=foo&tag=bar” (AND)
• “tag=foo bar || bar” (OR)
• “tag=-foo” (NOT)
• “tag=\-foo” (literal first-character hyphen)

The following parameters are valid only when accessing a resource that represents a set of objects. For example, /users/123/items represents a set of items, while /users/123/items/ABCD2345 represents a single item.

* Applies to format=atom and format={export_format} only. format=keys and format=versions have no default or maximum limit.

Note the difference between format=bib and content=bib. format=bib returns a formatted bibliography as XHTML, sorted according to the rules of the selected style. content=bib (valid only for format=atom, the default format mode) returns an individual formatted reference within the Atom <content> block for each item, with the Atom feed sorted according to the query parameters. format=bib processes the entire feed you are requesting without regard for any limit arguments, so it is generally a good idea to use it only with collections or tags.

The following bibliographic data formats can be used as 'format' and 'content' parameters:

For efficient usage of the API, clients should make conditional GET requests whenever possible. If If-Modified-Since-Version: <libraryVersion> is passed with a multi-object read request (e.g., <userOrGroupPrefix>/items) and data has not changed in the library since the specified version, the API will return 304 Not Modified. If If-Modified-Since-Version: <objectVersion> is passed with a single-object read request (e.g., <userOrGroupPrefix>/items/<itemKey>), a 304 Not Modified will be returned if the individual object has not changed.

While a conditional GET request that returns a 304 should be fast, some clients may wish to perform additional caching on their own, using stored data for a period of time before making subsequent conditional requests to the Zotero API. This makes particular sense when the underlying Zotero data is known not to change frequently. For example, a web page that displayed a bibliography from a Zotero collection might cache the returned bibliography for an hour, after which time it would make another conditional request to the Zotero API. If the API returned a 304, the web page would continue to display the cached bibliography for another hour before retrying.

Clients accessing the Zotero API should be prepared to handle two forms of rate limiting: backoff requests and hard limiting.

If the API servers are overloaded, the API may include a Backoff: <seconds> HTTP header in responses, indicating that the client should perform the minimum number of requests necessary to maintain data consistency and then refrain from making further requests for the number of seconds indicated. Backoff can be included in any response, including successful ones.

If a client has made too many requests within a given time period, the API may return 429 Too Many Requests with a Retry-After: <seconds> header. Clients receiving a 429 should wait the number of seconds indicated in the header before retrying the request.

Retry-After can also be included with 503 Service Unavailable responses when the server is undergoing maintenance.

Several examples of read request URLs and their responses:

These requests can be performed from the command line:

curl -H 'Zotero-API-Version: 2' 'https://api.zotero.org/users/475425/collections/9KH9TNSJ/items?format=atom'
curl -H 'Zotero-API-Version: 2' 'https://api.zotero.org/users/475425/items/X42A7DEE?format=atom'
curl -H 'Zotero-API-Version: 2' 'https://api.zotero.org/users/475425/items/X42A7DEE?format=atom&content=json,bib,html'
curl -H 'Zotero-API-Version: 2' 'https://api.zotero.org/users/475425/collections?format=atom'
curl -H 'Zotero-API-Version: 2' 'https://api.zotero.org/users/475425/collections/9KH9TNSJ/items?format=bib'

The API also supports write requests that allow the creation, modification, and deletion of data in online Zotero libraries.

Successful GET requests will return a 200 OK status code.

Conditional GET requests may return 304 Not Modified.

For any read or write request, the server may return a 400 Bad Request, 404 Not Found, or 405 Method Not Allowed for an invalid request and 500 Internal Server Error or 503 Service Unavailable for a server-related issue. Authentication errors (e.g., invalid API key or insufficient privileges) will return a 403 Forbidden.

Passing an Expect header, which is unsupported, will result in a 417 Expectation Failed response.

Library/object versioning or Zotero-Write-Token errors will result in 412 Precondition Failed or 428 Precondition Required.

429 Too Many Requests indicates that the client has been rate-limited.