Rate Limits#

Lookup Limits#

User Type	Lookups/Day	Included API calls/month	Notes
Anonymous	20	–	No account needed
Free account	60	–	Sign up at my.turtletech.us
Academic plan	20,000	10,000	EUR 4/month
Business plan	20,000	40,000	EUR 10/month

What Counts as a Lookup?#

Action	Counts?
DOI lookup (new paper)	Yes
ISBN lookup (new book)	Yes
Reverse lookup (paste text)	Yes
DOI/ISBN already in your collection	No
Manual entry	No
Re-format (change style)	No
Format endpoint	No
Group citation	No
Health check	No

Papers saved in your collections are free to re-lookup as long as they remain in the collection. Removing a paper means the next lookup will count against quota.

Paid plans allow usage beyond the included monthly API amount; overage usage is recorded for billing. The daily lookup limit still applies.

Batch and Collection Operations#

Batch formatting and verification use the normal lookup quota. Batch collection adds and BibTeX/RIS imports are available to signed-in Free accounts. Collection merge and batch move require an Academic or Business plan; those endpoints return HTTP 403 to a Free account:

{
  "error": "plan_required",
  "message": "This feature requires an Academic (EUR 4/mo) or Business (EUR 10/mo) plan.",
  "upgrade_url": "https://my.turtletech.us"
}

Collection Entry Limits#

Plan	Collections	Entries per collection
Free	4	200
Academic	10	1,000
Business	20	4,000

Reset#

Daily limits reset 24 hours after your first lookup of the day. Monthly limits reset on the first of each month.

Structured quota policy#

GET /api/v1/quota-policy returns the limits for Anonymous and Free use, the caller’s active plan, remaining lookups, reset interval, and symbolic account actions. Actions are stable identifiers such as sign_in, create_free_account, and view_plans; the response contains no redirect URL.

Quota exhaustion returns HTTP 429 with the same active-plan fields, a stable quota_exhausted error kind, a bounded human-readable message, and retry_after. Retry-After, X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset match the JSON body.

{
  "error": "quota_exhausted",
  "message": "Daily limit reached (20/day).",
  "retry_after": 3600,
  "anonymous_daily_limit": 20,
  "free_daily_limit": 60,
  "active_plan": "Anonymous",
  "limit": 20,
  "remaining": 0,
  "reset_seconds": 3600,
  "actions": ["sign_in", "create_free_account", "view_plans"]
}

Burst Limit#

Anonymous traffic is limited to 100 requests/minute per IP address. Authenticated traffic is limited to 600 requests/minute per credential.