Using the API

The API is comprised of six request types:

• OpenSearch supports two types of queries:A keyword search or an SRU-style CQL-formatted query.
  • Responses are returned in either Atom or RSS format
• SRU allows users to perform searches using a variety of indexes and operators using the SRU protocol
  • Responses are returned in either MARCXML or Dublin Core format
• Single Bibliographic Record allows users to request a single bibliographic record based on an identifer: OCLC Number or ISBN
  • Responses are returned in MARCXML Format
• Library Locations allows users to request holdings based on an identifier and geographic location or see all libraries in a specific geographic location
  • Responses are returned in either ISO 20775 Holdings format or JSON
• Library Catalog URL for a Record allows users to request a direct link to a given library catalog based on a submitted identifier and OCLC Symbol
  • Responses are returned in ISO 20775 Holdings format
• Formatted Citations allows users to request formatted bibliographic citations based on a submitted OCLC Number and citation format
  • an HTML encoded form suitable for incorporation into a web application

Usage Limits in Depth

Number of queries per day
There is a limit to the number of queries available within a single day set for each wskey. Initially all keys have a limit of 50,000 queries a day as a rolling 24 hour limit. This can be raised by any member with a key that needs to have more access for a particular use of the API. If your key needs to be increased please send a request to the OCLC support staff via our contact form.

Maximum number of records/libraries –
For any query the maximum number of records or library locations that can be requested is 100. It is possible to page through the results by sending another query with the next start position and request the next set of records or library locations up to another 100.  If not specified, results default to 10 records per request.

Total maximum number of records for a single specific query –
For any specific query, it is possible to page through all the results up to the 10,000th record. After that point, the system will appear to continue to page, but the next result will be a repeat of an earlier record.