Here you have detailed documentation of all available API functions. To get started, you can make the sample request for each endpoint, download an SDK, or run in Postman (see bottom of left navigation).

Search Books

Search and filter books based on matching a query, the ISBN, rating, and more fields. The query is semantically parsed using our own large ontology. That means you can search for "books about dogs" and will automatically also find books about "border collies" and other types without specifying them in the query.

Example Request and Response
    "available": 5999,
    "number": 10,
    "offset": 0,
    "books": [
            "id": 17200576,
            "title": "Journey to Hogwarts",
            "image": "https://covers.openlibrary.org/b/id/2520429-M.jpg"
            "id": 15954006,
            "title": "Inside Hogwarts",
            "subtitle": "Magical Paintbook",
            "image": "https://covers.openlibrary.org/b/id/2520430-M.jpg"
            "id": 16384516,
            "title": "Harry Potter and the Goblet of Fire",
            "image": "https://covers.openlibrary.org/b/id/12775900-M.jpg"
            "id": 14296534,
            "title": "Harry Potter and the Order of the Phoenix",
            "image": "https://covers.openlibrary.org/b/id/11416565-M.jpg"
            "id": 14530450,
            "title": "Great Gatsby (Silver Screen Edition)",
            "image": "https://covers.openlibrary.org/b/id/12791857-M.jpg"
            "id": 18810398,
            "title": "The Hobbit",
            "subtitle": "or, There and back again",
            "image": "https://covers.openlibrary.org/b/id/394001-M.jpg"
            "id": 13597674,
            "title": "The Name of the Wind",
            "subtitle": "The Kingkiller Chronicle : day one",
            "image": "https://covers.openlibrary.org/b/id/6282709-M.jpg"
            "id": 20778556,
            "title": "Two Towers : The Lord of the Rings",
            "subtitle": "Part Two",
            "image": "https://covers.openlibrary.org/b/id/13220226-M.jpg"
            "id": 20101114,
            "title": "Frankenstein (Silver Screen Edition)",
            "image": "https://covers.openlibrary.org/b/id/12791860-M.jpg"
            "id": 17798828,
            "title": "Bogar bárd meséi",
            "image": "https://covers.openlibrary.org/b/id/9326689-M.jpg"

Get Book Information

Get all information about a certain book.

Example Request and Response
    "id": 16384516,
    "title": "Harry Potter and the Goblet of Fire",
    "image": "https://covers.openlibrary.org/b/id/12775900-M.jpg",
    "identifiers": {
        "open_library_id": "OL82577W",
        "isbn_10": "0439139597",
        "isbn_13": "0439139597"
    "authors": [
            "id": 14136020,
            "name": "J. K. Rowling"
    "publish_date": 2000.0,
    "number_of_pages": 734.0,
    "description": "Celebrate 20 years of Harry Potter magic! \r\n\r\nThe Triwizard Tournament is to be held at Hogwarts. Only wizards who are over seventeen are allowed to enter – but that doesn't stop Harry dreaming that he will win the competition. Then at Hallowe'en, when the Goblet of Fire makes its selection, Harry is amazed to find his name is one of those that the magical cup picks out. He will face death-defying tasks, dragons and Dark wizards, but with the help of his best friends, Ron and Hermione, he might just make it through – alive!\r\n\r\nThese new editions of the classic and internationally bestselling, multi-award-winning series feature instantly pick-up-able new jackets by Jonny Duddle, with huge child appeal, to bring Harry Potter to the next generation of readers. It's time to PASS THE MAGIC ON",
    "rating": {
        "average": 0.912

Find Similar Books

Find books that are similar to the given book.

Example Request and Response
    "similar_books": [
            "id": 14296534,
            "title": "Harry Potter and the Order of the Phoenix",
            "image": "https://covers.openlibrary.org/b/id/11416565-M.jpg"
            "id": 16499448,
            "title": "Harry Potter and the Half-Blood Prince",
            "image": "https://covers.openlibrary.org/b/id/8235163-M.jpg"
            "id": 18610968,
            "title": "Blood and Fire",
            "image": "https://covers.openlibrary.org/b/id/10404497-M.jpg"
            "id": 20464852,
            "title": "Towers of midnight",
            "subtitle": "Wheel of Time Book 13",
            "image": "https://covers.openlibrary.org/b/id/6657713-M.jpg"
            "id": 13804028,
            "title": "Best of Robert Jordan",
            "subtitle": "The Shadow Rising; The Fires of Heaven; Lord of Chaos; A Crown of Swords (The Wheel of Time Series)",
            "image": "https://covers.openlibrary.org/b/id/3027823-M.jpg"
            "id": 14987824,
            "title": "MAR, Volume 7",
            "image": "https://covers.openlibrary.org/b/id/765103-M.jpg"
            "id": 19984854,
            "title": "The Daysong of the Knightbird",
            "image": "https://covers.openlibrary.org/b/id/1822804-M.jpg"
            "id": 17174416,
            "title": "The key",
            "image": "https://covers.openlibrary.org/b/id/8369732-M.jpg"
            "id": 20121054,
            "title": "Bring me the head of Prince Charming",
            "image": "https://covers.openlibrary.org/b/id/3965371-M.jpg"

Search Authors

Search for book authors by name or partial name. The response contains the author's name and their id. You can then use the id in the book search.

Example Request and Response
    "authors": [
            "id": 18826554,
            "name": "Morgan Horton Seacord"
            "id": 17858271,
            "name": "Morgan Housel"
            "id": 13486775,
            "name": "Morgan Howell"

Book Genres

The following list shows all supported book genres you can in the genres filter in the book search endpoint.

  • action
  • adventure
  • anthropology
  • astronomy
  • archaeology
  • architecture
  • art
  • aviation
  • biography
  • biology
  • business
  • chemistry
  • children
  • classics
  • contemporary
  • cookbook
  • crafts
  • crime
  • dystopia
  • economics
  • education
  • engineering
  • environment
  • erotica
  • essay
  • fairy_tales
  • fantasy
  • fashion
  • feminism
  • fiction
  • finance
  • folklore
  • food
  • gaming
  • gardening
  • geography
  • geology
  • graphic_novel
  • health
  • historical
  • historical_fiction
  • history
  • horror
  • how_to
  • humor
  • inspirational
  • journalism
  • law
  • literary_fiction
  • literature
  • magical_realism
  • manga
  • martial_arts
  • mathematics
  • medicine
  • medieval
  • memoir
  • mystery
  • mythology
  • nature
  • nonfiction
  • novel
  • occult
  • paranormal
  • parenting
  • philosophy
  • physics
  • picture_book
  • poetry
  • politics
  • programming
  • psychology
  • reference
  • relationships
  • religion
  • romance
  • science_and_technology
  • science_fiction
  • self_help
  • short_stories
  • society
  • sociology
  • space
  • spirituality
  • sports
  • text_book
  • thriller
  • travel
  • true_crime
  • war
  • writing
  • young_adult

Rate Limiting & Quotas

Each API plan comes with a daily quota of requests.

When you are on the free plan and your daily quota is used up, the API will respond with the error code 402 and no more calls can be made until your quota resets.

You have complete control over your quota by looking at your console dashboard and checking the API response headers that appear with every answer from the API. These response headers are:

  • X-API-Quota-Request: The number of requests used.
  • X-API-Quota-Used: The number of requests used in total today. This number resets to zero at midnight UTC (click here to compare to your local time zone).
  • X-API-Quota-Left: The number of requests left today (depends on your plan).

Rate Limiting

There is a limit of how many requests you can make per second. The limits depend on the plan you are on. If you try making more requests you will receive a 429 error.

  • Free: 60 requests in 1 minute
  • Magazine: 2 requests per second
  • Book: 10 requests per second
  • Tome: 20 requests per second


To use the API you need an API key. You can get a free one by simply signing up here.

Once you have your API key, you have to put it in the request URL for every request you make like so ?api-key=YOUR-API-KEY.

Attention: Only the first query parameter is prefixed with a ? (question mark), all subsequent ones will be prefixed with a & (ampersand). That is how URLs work and nothing related to our API. Here's a full example with two parameters api-key and query: https://api.bigbookapi.com/search-books?api-key=YOUR-API-KEY&query=romance.

Alternatively, you can put the API key in the request header as x-api-key.