books
Project Gutenberg (Gutendex)
The classic collection of around 75,000 free public-domain ebooks, with the Gutendex service exposing its catalogue as JSON for searching by title or author. You can also browse and download directly from the Gutenberg website. It is the go-to for complete, free ebook texts of out-of-copyright works, though the catalogue query can be slow or occasionally time out.
Por qué es útil y cómo funciona
Project Gutenberg is the oldest and most established source of complete, freely downloadable public-domain ebooks, covering classic literature, historical texts, and early scientific works. You search by title or author on the Gutenberg website or via the Gutendex JSON catalogue, and can download in EPUB, Kindle, or plain-text formats with no account required. The collection focuses on works where US copyright has expired, so it is strongest for 19th-century and early 20th-century titles.
Qué contiene
Approximately 78,000 free ebooks, primarily English-language but including works in dozens of languages, all in the public domain.
Acceso por API
https://gutendex.com/books?search= ... ; https://gutendex.com/books/ <id>
Acceso
Programmatic API access (a key may be required, see the API tag).