Best Books APIs in 2026

The top 15 of 26 free Books APIs, ranked by how easy they are to start with (API key, HTTPS, CORS), how reliable they are in our daily health checks, and what developers rate them. Greenlit Books API takes the top spot.

Last tested Oct 24, 2026 · Rankings update daily

1
Greenlit Books API
Online · 1178 ms
Catalog of practical AI books with search, series, glossary and a claim ledger.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
2
KDP Intelligence API
Online · 1181 ms
KDP niche demand scores, competition analysis and revenue estimates.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
3
PoetryDB API
Online · 623 ms
Enables you to get instant data from our vast poetry collection.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
4R
Runyankole Bible API
Online · 1069 ms
Free REST API for the Runyankore-Rukiga Bible — 66 books, 31106 verses.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
5T
Thirukkural API
Online · 814 ms
1330 Thirukkural poems and explanation in Tamil and English.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
6
Wizard World API
Online · 1084 ms
Get information from the Harry Potter universe.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
7
BookRank API
Online · 1311 ms
Book rankings from open reader ratings: books, series, reading orders and authors.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
8
Penguin Publishing API
Online · 2410 ms
Books, book covers and related data.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
9
Quran API
Online · 2855 ms
RESTful Quran API with multiple languages.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
10
Quran Cloud API
Online · 1880 ms
A RESTful Quran API to retrieve an Ayah, Surah, Juz or the entire Holy Quran.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
11
Quran-api
Online · 1808 ms
Free Quran API Service with 90+ different languages and 400+ translations.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
12
Urantia Papers API
Online · 1200 ms
Full-text + semantic search across the Urantia Papers, with audio narration, entities, translations.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
13B
Bible-api
Online · 1322 ms
Free Bible API with multiple languages.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
14
Crossref Metadata Search API
Online · 755 ms
Documentation for Crossref's REST API.
- No API key needed
- HTTPS
No authHTTPSCORS ?
15
Wolne Lektury API
Online · 1079 ms
API for obtaining information about e-books available on the WolneLektury.pl website.
- No API key needed
- HTTPS
No authHTTPSCORS ?

Books APIs compared

Top Books APIs compared
API	API key	HTTPS	CORS	Uptime	Response	Rating
Greenlit Books	No	Yes	Yes	Up	1178 ms	Not rated
KDP Intelligence	No	Yes	Yes	Up	1181 ms	Not rated
PoetryDB	No	Yes	Yes	Up	623 ms	Not rated
Runyankole Bible	No	Yes	Yes	Up	1069 ms	Not rated
Thirukkural	No	Yes	Yes	Up	814 ms	Not rated
Wizard World	No	Yes	Yes	Up	1084 ms	Not rated
BookRank	No	Yes	Yes	Up	1311 ms	Not rated
Penguin Publishing	No	Yes	Yes	Up	2410 ms	Not rated
Quran	No	Yes	Yes	Up	2855 ms	Not rated
Quran Cloud	No	Yes	Yes	Up	1880 ms	Not rated

More Books APIs

Best Books API FAQ

What is the best free Books API in 2026?

Based on access, reliability and developer ratings, the top free Books APIs right now are Greenlit Books API, KDP Intelligence API and PoetryDB API. Greenlit Books API ranks first. Rankings update daily from health checks of all 26 Books APIs in the directory.

What is the best Books API without an API key?

Greenlit Books API, KDP Intelligence API and PoetryDB API need no API key, so you can call them without signing up. 20 of the 26 ranked Books APIs are keyless.

Which Books API works from the browser?

Greenlit Books API, KDP Intelligence API and PoetryDB API support CORS over HTTPS, so front-end JavaScript can call them directly without a proxy.

How are these APIs ranked?

Each API gets a score from: no API key (+), HTTPS (+), CORS support (+), 30-day uptime and response time from our daily health checks, and ratings from developers on this site. APIs that failed three checks in a row are left out until they recover.