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Zotero Web API Documentation

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

Base URL

The base URL for all API requests is

https://api.zotero.org

All requests must use HTTPS.

API Versioning

Multiple versions of the API are available, and production code should always request a specific version. This page documents API version 3, which is currently the default and recommended version.

Clients can request a specific version in one of two ways:

  1. Via the Zotero-API-Version HTTP header (Zotero-API-Version: 3)
  2. Via the v query parameter (v=3)

Use of the Zotero-API-Version header is recommended for production code. The v parameter can be used for easier debugging and sharing of API requests or in clients that can't pass arbitrary HTTP headers.

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

Version Transitions

At most times, API changes are made in a backwards-compatible manner. Occasionally, however, backwards-incompatible changes may need to be made. When this occurs, a new API version will be made available without changing the default version for clients that don't request a specific version. After a transition period, the new API version will become the default. If an API version is discontinued, clients requesting the discontinued version will receive the oldest available version. Announcements regarding API version transitions will always be made ahead of time on zotero-dev.

Authentication

Authentication is not required for read access to public libraries.

Accessing non-public libraries 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.

API keys can be included in requests in one of three ways:

  1. As an HTTP header in the form Zotero-API-Key: P9NiFoyLeZu2bZNvvuQPDWsd
  2. As an HTTP header in the form Authorization: Bearer P9NiFoyLeZu2bZNvvuQPDWsd
  3. As a URL query parameter, in the form key=P9NiFoyLeZu2bZNvvuQPDWsd

Use of an HTTP header is recommended, as it allows use of URLs returned from the API (e.g., for pagination) without modification.

Authorization: Bearer is also the authentication mechanism for OAuth 2.0. While Zotero currently supports only OAuth 1.0a, when support for OAuth 2.0 is added, clients will no longer need to extract the API key from the OAuth response and pass it to the API separately.

Resources

User and Group Library URLs

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.

URI Description
<userOrGroupPrefix>/items The set of all items in the library, excluding trashed items
<userOrGroupPrefix>/items/top The set of all top-level items in the library, excluding trashed items
<userOrGroupPrefix>/items/trash The set of items in the trash
<userOrGroupPrefix>/items/<itemKey> A specific item in the library
<userOrGroupPrefix>/items/<itemKey>/children The set of all child items under a specific item
<userOrGroupPrefix>/items/<itemKey>/tags The set of all tags associated with a specific item
<userOrGroupPrefix>/tags The set of all tags in the library
<userOrGroupPrefix>/tags/<url+encoded+tag> The set of tags (i.e., of all types) matching a specific name
<userOrGroupPrefix>/collections The set of all collections in the library
<userOrGroupPrefix>/collections/top The set of all top-level collections in the library
<userOrGroupPrefix>/collections/<collectionKey> A specific collection in the library
<userOrGroupPrefix>/collections/<collectionKey>/collections The set of subcollections within a specific collection in the library
<userOrGroupPrefix>/collections/<collectionKey>/items The set of all items within a specific collection in the library
<userOrGroupPrefix>/collections/<collectionKey>/items/top The set of top-level items within a specific collection in the library
<userOrGroupPrefix>/collections/<collectionKey>/tags The set of tags within a specific collection in the library
<userOrGroupPrefix>/searches The set of all saved searches in the library
<userOrGroupPrefix>/searches/<searchKey> A specific saved search in the library

Other URLs

URI Description
/keys/<key> The user id and privileges of the given API key.
Use the DELETE HTTP method to delete the key. This should generally be done only by a client that created the key originally using OAuth.
/users/<userID>/groups The set of groups the current API key has access to, including public groups the key owner belongs to even if the key doesn't have explicit permissions for them.

Read Requests

The following parameters affect the format of data returned from read requests. All parameters are optional.

General Parameters

The following parameters are valid for all read requests:

Parameter Values Default Description
format atom, bib, json, keys, versions, export format json (or atom if the Accept header includes application/atom+xml) atom will return an Atom feed suitable for use in feed readers or feed-reading libraries.
bib, valid only for item requests, will return a formatted bibliography as XHTML. bib mode is currently limited to a maximum of 150 items.
json will return a JSON array for multi-object requests and a single JSON object for single-object requests.
keys, valid for multi-object requests, will return a newline-separated list of object keys. keys mode has no default or maximum limit.
versions, valid for multi-object collection, item, and search requests, will return a JSON object with Zotero object keys as keys and object versions as values. Like keys, versions mode has no default or maximum limit.
Export formats, valid only for item requests, produce output in the specified format.

Parameters for "format=json"

Parameter Values Default Description
include bib, citation, data, export format
Multiple formats can be specified by using a comma as the delimiter (include=data,bib).
data Formats to include in the response:
bib, valid only for item requests, will return a formatted reference for each item.
citation, valid only for item requests, will return a formatted citation for each item.
data (the default) will include all writeable fields in JSON format, suitable for modifying and sending back to the API.
Export formats, valid only for item requests, will return data in the specified format for each item.

Parameters for "format=atom"

Parameter Values Default Description
content bib, citation, html, json, export formats, none
Multiple formats can be specified by using a comma as the delimiter (content=json,bib).
html The format of the Atom response's <content> node:
html (the default) will return an XHTML representation of each object, useful for display in feed readers and for parsing by XML tools.
json, currently valid only for item and collection requests, will return a JSON representation of all the item's fields.
bib, valid only for item requests, will return a formatted reference for each item.
citation, valid only for item requests, will return a formatted citation for each item.
Export formats, valid only for item requests, will return data in the specified format for each item.
If additional data is not required, use none to decrease the response size.
If multiple formats are requested, <content> will contain multiple <zapi:subcontent> elements (in the http://zotero.org/ns/api namespace), each with a zapi:type attribute matching one of the specified content parameters.

Parameters for "format=bib", "include/content=bib", "include/content=citation"

Parameter Values Default Description
style string chicago-note-bibliography Citation style to use for formatted references. Can be either the file name (without the .csl extension) of one of the styles in the Zotero Style Repository (e.g., apa) or the URL of a remote CSL file.

Note the difference between format=bib and include=bib/content=bib. format=bib returns a formatted bibliography as XHTML, sorted according to the rules of the selected style. include=bib (valid only for format=json (the default format mode) and format=atom) returns an individual formatted reference within the JSON data block or Atom <content> block for each item, with the results or 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.

Export Formats

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

Parameter Description
bibtex BibTeX
biblatex BibLaTeX
bookmarks Netscape Bookmark File Format
coins COinS
csljson Citation Style Language data format
mods MODS
refer Refer/BibIX
rdf_bibliontology Bibliographic Ontology RDF
rdf_dc Unqualified Dublin Core RDF
rdf_zotero Zotero RDF
ris RIS
tei Text Encoding Initiative (TEI)
wikipedia Wikipedia Citation Templates

Searching

Search Parameters

Parameter Values Default Description
itemKey string null A comma-separated list of item keys. Valid only for item requests. Up to 50 items can be specified in a single request.
itemType search syntax null Item type search
q string null Quick search. Searches titles and individual creator fields by default. Use the qmode parameter to change the mode. Currently supports phrase searching only.
qmode titleCreatorYear, everything titleCreatorYear Quick search mode. To include full-text content in the search, use everything. Searching of other fields will be possible in the future.
since integer 0 Return only objects modified after the specified library verson.
tag search syntax null Tag search

Search Syntax

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)

Be sure to URL-encode search strings if required by your client or library.

Sorting and Pagination

Sorting and Pagination Parameters

The following parameters are valid only for multi-object read requests such as <userOrGroupPrefix>/items, with the exception of format=bib requests, which do not support sorting or pagination.

Parameter Values Default Description
sort dateAdded, dateModified, title, creator, type, date, publisher, publicationTitle, journalAbbreviation, language, accessDate, libraryCatalog, callNumber, rights, addedBy, numItems (tags) dateModified (dateAdded for Atom) The name of the field by which entries are sorted
direction asc, desc varies by sort The sorting direction of the field specified in the sort parameter
limit integer 1-100* 50 The maximum number of results to return with a single request. Required for export formats.
start integer 0 The index of the first result. Combine with the limit parameter to select a slice of the available results.

Total Results

Responses for multi-object read requests will include a custom HTTP header, Total-Results, that provides the total number of results matched by the request. The actual number of results provided in a given response will be no more than 100.

When the total number of results matched by a read request is greater than the current limit, the API will include pagination links in the HTTP Link header. Possible values are rel=first, rel=prev, rel=next, and rel=last. For some requests, the header may also include a rel=alternate link for the relevant page on the Zotero website.

GET https://api.zotero.org/users/12345/items?limit=30
Link: <https://api.zotero.org/users/12345/items?limit=30&start=30>; rel="next",
 <https://api.zotero.org/users/12345/items?limit=30&start=5040>; rel="last",
 <https://www.zotero.org/users/12345/items>; rel="alternate"

(Newlines are inserted here for clarity.)

Caching

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., /users/1/items) and data has not changed in the library since the specified version, the API will return 304 Not Modified. Single-object conditional requests are not currently supported, but will be supported in the future.

While a conditional GET request that returns a 304 should be fast, some clients may wish or need 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 or when the data will be accessed frequently. For example, a website 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 website would continue to display the cached bibliography for another hour before retrying. This would prevent the website from making a request to the Zotero API every time a user loaded a page.

Rate Limiting

[Not all rate limits are currently enforced, but clients should be prepared to handle them.]

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.

Example GET Requests and Responses

Several examples of read request URLs and their responses:

Multi-object JSON response: top-level items in a collection
Request https://api.zotero.org/users/475425/collections/9KH9TNSJ/items/top?v=3
Response https://gist.github.com/6eeace93a5c29775d39c
Multi-object JSON response: collections for a user
Request https://api.zotero.org/users/475425/collections?v=3
Response https://gist.github.com/0bc17ca64ee7d3bc9063

HTTP Status Codes

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.

Additional API Documentation