name: ISBNdb API Rate Limits
description: Rate limiting policies for the ISBNdb book and ISBN database REST API
url: https://isbndb.com/api-documentation
limits:
  - plan: Basic
    window: second
    max_requests: 1
    description: One request per second for Basic plan subscribers
  - plan: Basic
    window: day
    max_requests: 1000
    description: 1,000 daily API calls for Basic plan subscribers; resets at 00:00 UTC
  - plan: Academic
    window: second
    max_requests: 1
    description: One request per second for Academic plan subscribers
  - plan: Academic
    window: day
    max_requests: 2000
    description: 2,000 daily API calls for Academic plan; resets at 00:00 UTC
  - plan: Premium
    window: second
    max_requests: 3
    description: Three requests per second for Premium plan subscribers
  - plan: Premium
    window: day
    max_requests: 5000
    description: 5,000 daily API calls for Premium plan subscribers; resets at 00:00 UTC
  - plan: Pro
    window: second
    max_requests: 5
    description: Five requests per second for Pro plan subscribers
  - plan: Pro
    window: day
    max_requests: 15000
    description: 15,000 daily API calls for Pro plan subscribers; resets at 00:00 UTC
  - plan: Enterprise
    window: second
    max_requests: 10
    description: Ten requests per second for Enterprise plan subscribers
  - plan: Enterprise
    window: day
    max_requests: 50000
    description: 50,000 daily API calls for Enterprise plan subscribers; resets at 00:00 UTC
headers:
  - name: ratelimit
    description: Current rate limit status returned in every API response header
  - name: ratelimit-policy
    description: Rate limit policy details returned in every API response header
error_responses:
  - code: 429
    message: Per minute quota exceeded, please try again later
    description: Returned when per-minute request rate is exceeded
  - code: 429
    message: Daily quota exceeded, please try again later
    description: Returned when daily call limit is exhausted; resets at 00:00 UTC
  - code: 401
    message: Full authentication is required to access this resource
    description: Returned when x-api-key header is missing, invalid, or subscription is inactive
reset: 00:00 UTC daily
monitoring_endpoint: GET /key
monitoring_description: Returns current API key details and quota usage information