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Provides structured data about Library of Congress collections.


The application programming interface (API) provides structured data about Library of Congress collections in JSON and YAML formats. Software programs routinely access the JSON/YAML API to keep the website updated as new digital content is added to the Library's collections. For example, JSON data is used to build pages for items (, collections (, searches (, and more.

However, in addition to being a resource for the computer applications powering the website, the API can be used by developers, digital librarians, and researchers to directly retrieve digital collections information formatted as JSON or YAML data.

Retrievable Information

The JSON/YAML API provides information about the following content on the Library of Congress website:

  • items (books, archived websites, photos, videos, maps, manuscripts, etc.)
    1. Note: not all the items you find on the website necessarily belong to a historic library collection. For example, many recordings of Library of Congress events are shared on the website. So you may find videos like this virtual event recording of the 2020 Newspaper Navigator Data Jam hosted by LC Labs alongside digitized historical materials.
  • collections (groups of items selected by subject matter experts according to a theme or other principle)
  • images (thumbnails and higher resolution formats)
  • metadata (descriptive and/or bibliographic information retrieved from library systems)
    1. Note: the API does not include records from the library catalog (although items that have been digitized are retrievable). See the MARC Open Access dataset for bulk access to the catalog records up through 2014.

Get Help

Additional examples and Jupyter notebooks implementing the API are available in the Library of Congress' data-exploration GitHub repository.

If you have questions about using the API, the API's data coverage, data structure, or technical access pathways that are not answered by the documentation, please contact the Library's Digital Innovation Lab (LC Labs) team at

If you have questions about a specific digital collection, please contact the Library's reference staff via the Ask a Librarian service.