Open Library Subjects

How to Use This API

1. Browse a Subject

https://openlibrary.org/subjects/love.json

2. With Details Mode

https://openlibrary.org/subjects/space_exploration.json?details=true

Details mode adds publisher info, ISBNs, and full author objects to each work entry.

3. Pagination and Limiting

https://openlibrary.org/subjects/philosophy.json?limit=20&offset=40

Use limit (default 50, max 1000) and offset for pagination. The response includes work_count for total results.

4. Multi-word and Nested Subjects

https://openlibrary.org/subjects/computer_science.json

https://openlibrary.org/subjects/science_history.json

Use underscores for spaces. Subjects can be hierarchical — /subjects/science.json gives broad science, /subjects/science_fiction.json gives a sub-genre.

5. Response Format

{
  "key": "/subjects/love",
  "name": "love",
  "work_count": 1234,
  "works": [
    {
      "key": "/works/OL123W",
      "title": "Romeo and Juliet",
      "first_publish_year": 1597,
      "edition_count": 500,
      "cover_id": 12345,
      "cover_edition_key": "OL123M",
      "authors": [{"name": "William Shakespeare", "key": "/authors/OL1A"}],
      "subjects": ["love", "tragedy", "drama"]
    }
  ]
}

6. JavaScript — Books by Subject

fetch('https://openlibrary.org/subjects/science_fiction.json?limit=5')
  .then(r => r.json())
  .then(d => {
    console.log(`Found ${d.work_count} works on "${d.name}"`);
    d.works.forEach(w => {
      const authors = w.authors?.map(a => a.name).join(', ') || 'Unknown';
      console.log(`${w.title} (${w.first_publish_year}) — ${authors}`);
    });
  });

7. Python — Top Books on a Topic

import requests

resp = requests.get('https://openlibrary.org/subjects/philosophy.json', params={
    'limit': 10, 'details': True
})
data = resp.json()
for work in data['works']:
    authors = ', '.join(a['name'] for a in work.get('authors', []))
    print(f"{work['title']} ({work['first_publish_year']}) — {authors}")
    print(f"  Editions: {work['edition_count']}")
    if 'publishers' in work:
        print(f"  Publishers: {', '.join(work['publishers'][:3])}")

8. Python — Paginate Through All Results

import requests

subject = 'artificial_intelligence'
all_works = []
page = 0
page_size = 100

while True:
    resp = requests.get(
        f'https://openlibrary.org/subjects/{subject}.json',
        params={'limit': page_size, 'offset': page * page_size}
    )
    data = resp.json()
    works = data.get('works', [])
    if not works:
        break
    all_works.extend(works)
    page += 1

print(f"Total works found: {len(all_works)}")