Free Books API
Search millions of books by title or author and pull full details — publisher, page count, cover image — for any ISBN-10 or ISBN-13, courtesy of the Internet Archive's Open Library.
Endpoints
| Method | Endpoint | Description | Source |
|---|---|---|---|
GET |
/api/v1/books/search?q=dune&limit=10 |
Search books by title/author | Open Library |
GET |
/api/v1/books/isbn/{isbn} |
Full book details by ISBN-10/13 | Open Library |
Full request/response details for every endpoint are in the API documentation.
Example request
curl "https://freeopenapi.dev/api/v1/books/isbn/9780441172719" \
-H "X-Api-Key: YOUR_API_KEY"
Works the same with ?apiKey=... as a query parameter. Every response carries
X-RateLimit-Limit / X-RateLimit-Remaining headers so you can track your budget.
Frequently asked questions
Is the books API really free?
Yes. The free tier includes 100 requests per day and only requires a verified email address — no credit card. Paid Pro and Business tiers raise the daily limit.
Do responses include cover images?
Yes, search results and ISBN lookups include a cover image URL when Open Library has one on file.
Can I search by author?
Yes, the search endpoint matches both titles and author names in one query.
How do I get an API key?
Request a key with your email address on the Docs page, click the confirmation link we send you, and your key is active immediately on the free tier.