Search the world's largest library catalog via OCLC WorldCat API
WorldCat is the world's largest network of library content, aggregating catalogs from 10,000+ libraries across 170+ countries. The Search API provides access to 500M+ bibliographic records — books, journals, dissertations, media, and more — with holdings information showing which libraries own each item. Essential for interlibrary loan discovery, collection analysis, and comprehensive bibliographic searches. Requires a WSKey (free for non-commercial use).
# Register at https://platform.worldcat.org/
# Obtain a WSKey (API key) for your application
# OAuth 2.0 client credentials flow
curl -X POST "https://oauth.oclc.org/token" \
-u "$WSKEY_CLIENT_ID:$WSKEY_SECRET" \
-d "grant_type=client_credentials&scope=wcapi"