Documentation
The Union Catalog exposes its aggregated metadata through several machine interfaces. These include OAI-PMH harvesting, a JSON search API, item metadata in JSON and JSON-LD, an MCP endpoint for AI assistants, an RSS feed of recent additions, and sitemaps for crawlers. All interfaces are read-only and require no registration or API key.
API reference
Documents every interface with working examples, including endpoints, parameters,
and response formats.
OAI-PMH harvester guide
Covers the harvesting endpoint in depth, including verbs, sets, identifiers,
selective harvesting, resumption tokens, deleted records, and the aggregator
conventions the catalog follows.
Terms of Service
The Union Catalog's terms of service.
The about page records the catalog's history and stewardship.