books
Internet Archive Texts
The text and book collection on archive.org, comprising more than 40 million digitized items, some available only through controlled lending. A keyless search-and-metadata interface lets you find items and open them in the reader. Use it to establish that a book or document exists and to read public-domain material, bearing in mind that in-copyright full text is lending-gated and the service can throttle under heavy load.
Why it’s useful & how it works
Search/metadata APIs keyless, work both ways; throttled under load (shared IA reliability wobbles). Full text of in-copyright books is lending-gated — use for existence/metadata + deep link.
What’s inside
~40M+ text items.
API access
https://archive.org/advancedsearch.php?q=...&output=json ; https://archive.org/metadata/ <id>
Access
Programmatic API access (a key may be required — see the API tag).