British National Bibliography vs Gutendex

The British National Bibliography is the British Library's record of everything published in the UK and Ireland since 1950, now published as BIBFRAME/RDA linked open data through the multi-national "Share Family" platform. Its original bnb.data.bl.uk endpoint has been offline since the Library's October 2023 cyber-attack destroyed its digital infrastructure; the catalog has since resurfaced on a beta institutional search portal, per the Library's own service-status and metadata-services pages.

Gutendex is a free, open-source JSON API — built independently of Project Gutenberg — that wraps its roughly 75,000 public-domain ebooks with searchable, paginated metadata: authors, subjects, bookshelves, languages, and direct links to every available download format from plain text to EPUB and Kindle. No account or key is needed to query it, and the project's own source enables cross-origin requests from any domain rather than restricting them. Anyone needing sustained high-volume traffic is asked to run their own instance of the open-source server instead of hammering the public one.