Greenlit Books API vs Penguin Publishing API

Two free Books APIs compared on access, reliability and developer ratings, using data from our daily health checks.

The verdict

Choose Greenlit Books API if you want faster responses.
Choose Penguin Publishing API if its data fits your use case better; on access and reliability it's level with Greenlit Books API.

	Greenlit Books API	Penguin Publishing API
What it does	Catalog of practical AI books with search, series, glossary and a claim ledger.	Books, book covers and related data.
Provider	Greenlit Books	penguinrandomhouse.biz
API key	Not needed	Not needed
HTTPS	Yes	Yes
CORS (browser calls)	Yes	Yes
Status today	Online · 1178 ms	Online · 2410 ms
Uptime (30 days)	Up	Up
Developer rating	Not rated yet	Not rated yet
Price	Free / free tier	Free / free tier

Catalog of practical AI books with search, series, glossary and a claim ledger.

The Greenlit Books public JSON API: books, series, concepts, and ranked search over plain HTTP GET. No auth, no scraping, OpenAPI 3.1 spec included.

Strengths

Books, book covers and related data.

Strengths

Prototyping or a tutorial? Pick the one that needs no API key (both qualify).
Calling from a web page? You need CORS. Otherwise route requests through your own server or a serverless function.
Going to production? Favour HTTPS, a strong uptime record and a provider with clear rate limits and terms. Check each API's docs before you commit.
Still unsure? Both are free to try: send one request to each and compare the data you get back.

Neither needs an API key; you can call both straight away.