Integrating BookLink.fyi

BookLink.fyi gives every book one link that shows every place to get it: new, used, ebook, audiobook, libraries, and free public-domain sources. You can send your readers to it with a plain link, or look books up through a small JSON API. It is free, and the basics need no account or API key.

This page is also available as plain markdown at /developers.md, and there is a short index for AI agents at /llms.txt.

The 60-second integration: one link

If you have the book's ISBN, this is the whole integration:

<a href="https://booklink.fyi/isbn/9780593983768" target="_blank" rel="noopener">
  More stores &amp; libraries
</a>

/isbn/{isbn} accepts ISBN-10 or ISBN-13, with or without hyphens, and redirects to the book's page. If we have never seen the book, the first person to click creates it; it takes a second or two.

The page you land on describes the edition that ISBN belongs to. If you hold several ISBNs for a book, send the mainstream trade edition (the ordinary hardcover or paperback) rather than a large-print, library-binding, audiobook or translated edition.

No ISBN? Link to a search instead. When we are confident about the match the reader lands directly on the book; otherwise they see results to pick from.

https://booklink.fyi/search?q=There+Is+No+Antimemetics+Division+qntm

Already have a retailer link (Amazon, Bookshop.org, Barnes & Noble, Goodreads, Kobo, Apple Books, and more)? Hand it to us and we will work out the book:

https://booklink.fyi/resolve?url=https%3A%2F%2Fbookshop.org%2Fa%2F114321%2F9780593983768

In React:

function BookLinkButton({ isbn, title, author }) {
  const href = isbn
    ? `https://booklink.fyi/isbn/${isbn}`
    : `https://booklink.fyi/search?q=${encodeURIComponent(`${title} ${author ?? ""}`.trim())}`;
  return (
    <a href={href} target="_blank" rel="noopener">
      More options on BookLink.fyi
    </a>
  );
}

URL reference

URL What it does
/isbn/{isbn} Redirects to the book's page. 404 page if the ISBN is unknown to every source.
/search?q={text} Goes straight to the book on a confident match, else shows results.
/resolve?url={retailer-url} Redirects to the book, else to a search, else home.
/book/{slug} The canonical book page. Stable; safe to store.
/b/{slug} Short form of the same page.

JSON API

Base URL https://booklink.fyi/api/v1. Responses are JSON. CORS is open (Access-Control-Allow-Origin: *), so browser-side calls work.

  • Auth: none required. An optional X-API-Key header raises your rate limit. Keys are issued by hand for now: write to [email protected].
  • Rate limits: 20 requests/minute per IP without a key, 120/minute with one. Over the limit returns 429.
  • source parameter: always send source=app-{yourname} so we can tell your traffic apart and get in touch before changing anything you depend on.
  • Machine-readable schema: /openapi.json (human view at /docs).

GET /api/v1/resolve — retailer URL to book

curl "https://booklink.fyi/api/v1/resolve?source=app-example&url=https%3A%2F%2Fbookshop.org%2Fa%2F114321%2F9780593983768"

{
  "status": "found",
  "booklink_url": "https://booklink.fyi/book/there-is-no-antimemetics-division-qntm",
  "short_url": "https://booklink.fyi/b/there-is-no-antimemetics-division-qntm",
  "title": "There Is No Antimemetics Division",
  "authors": ["qntm"],
  "cover_url": "https://…",
  "isbn": "9780593983768"
}

When the URL cannot be pinned to one book you get "status": "not_found" with a search_url you can send the reader to instead.

GET /api/v1/search — text to candidate books

Parameters: q (required, up to 500 characters), limit (1–20, default 5).

curl "https://booklink.fyi/api/v1/search?source=app-example&q=piranesi&limit=3"

{
  "status": "found",
  "results": [
    {
      "title": "Piranesi",
      "authors": ["Susanna Clarke"],
      "cover_url": "https://…",
      "isbn": "9781635575637",
      "published_date": "2020-09-15",
      "search_url": "https://booklink.fyi/search?q=piranesi&pick=0"
    }
  ]
}

Search results are candidates, not saved books, so they carry a search_url rather than a permanent slug. The book is created when a person follows that link. If you build these links yourself on a server, append &human=1.

Things that will trip you up

  1. Do not send Referer: https://booklink.fyi (the bare origin, no path, no trailing slash). Every route, including the API, answers that with 403. Links from your own site are unaffected; this only bites hand-rolled HTTP clients that set a Referer.
  2. Use an honest User-Agent, and keep the words crawler, spider and scraper out of it. Requests that identify as a known search, AI or uptime-monitoring bot, or contain those words, can read existing books but never create new ones. An automated check of /isbn/{isbn} for a book we have not seen yet will therefore get a 404 that a real reader would not.
  3. Do not crawl or prefetch /search, /isbn/, /resolve, /go/ or /api/. They are disallowed in robots.txt because following them creates records and logs clicks. Book pages (/book/…, /b/…) are fine to fetch.
  4. Calling from a server? Your whole backend is one IP sharing the 20/minute anonymous limit. Ask for a key, and cache: a book's slug and booklink_url do not change.
  5. Content-Security-Policy. Plain links need nothing. If you call the API from the browser, add https://booklink.fyi to connect-src. Our cover images are served from several hosts, so img-src https: is the practical setting.

Affiliate links and what is coming

Retailer links on BookLink.fyi pages carry BookLink's affiliate tags; that is what pays for the service. Three things are planned but not available yet:

  • registered partners using their own affiliate tags on the retailers where they have a program;
  • a JSON endpoint returning a book's retailer links, so you can render the buttons on your own page in your own design;
  • a drop-in embed (script tag or iframe) for sites without a developer.

If one of those would change what you build, tell us — it decides the order we build them in: [email protected]