Bible-api
Free Bible API with multiple languages

Book rankings from open reader ratings: books, series, reading orders and authors.
BookRank API is a free Books API that requires no API key, is served over HTTPS and supports CORS, so it can be called from the browser.
Every score, rank and series on BookRank is also a plain file: a free JSON API with no key, lookups by ISBN, and the whole catalogue as CSV.
Details from openbookrank.com.

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Free Bible API with multiple languages
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The BookRank API is provided by BookRank (openbookrank.com). Every score, rank and series on BookRank is also a plain file: a free JSON API with no key, lookups by ISBN, and the whole catalogue as CSV.
Yes. The BookRank API is listed in the Books category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
No. The BookRank API requires no authentication, so you can start making requests without signing up.
Yes. The BookRank API supports CORS, so front-end JavaScript can call it directly.
Yes. The BookRank API is served over HTTPS, so it's safe to use in production.