Metadata Plus gives you enhanced access to all our supported APIs, guarantees service levels and support, and additional features such as snapshots and priority service/rate limits.
To use Metadata Plus, an optional paid-for service, you do not need to be a member. In addition to enhanced access to all our supported APIs (OAI-PMH and REST APIs) and metadata in XML and JSON, Metadata Plus provides you with:
Metadata Plus users may use either or both of the included API interfaces:
Metadata Plus users’ queries will be prioritised via isolated resources. The limit number can depend on the system state and may need to change. If it does, Crossref will publish it in the response headers.
| Feature | Definition and rates effective until 31st of January 2027 | Definition and rates effective from 1st of February 2027 |
|---|---|---|
| Priority Service/Rate Limits for REST API single DOI lookup. | Minimum number of queries per second per IP address. Rate limiting of the API is primarily on a per IP basis. If a method allows, for example, for 150 requests per rate limit window, then it allows 150 requests per IP. | Usage limits on a per-token basis. Rate limit: 64 requests per second, concurrency limit: 16 simultaneous requests. |
| Priority Service/Rate Limits for REST API single DOI lookup. | Usage limits on a per-token basis. Rate limit: 64 requests per second, concurrency limit: 16 simultaneous requests. | |
| Snapshots | User-requested full-file downloads. Data may be requested in JSON and XML via an interface separate from each API. Pre-generated reports available via machine request and human user interface. | User-requested full-file downloads. Data may be requested in JSON and XML via an interface separate from each API. Additional formats may be available in the future. Pre-generated reports available via machine request and human user interface. |
In the exceptional event that a release is not backwards-compatible, Crossref will provide extensive lead time to communicate the changes, as part of our proactive support for Plus users.
Start by contacting us about Metadata Plus access. Plus subscribers can create their own API keys to use either or both the OAI-PMH and the REST API. Learn more in our extensive documentation for both the REST API and OAI-PMH interfaces.
Crossref will maintain an aggregated, average uptime for all of the interfaces that together comprise the Crossref Metadata Service of 99.5%, reported on a monthly basis. Crossref will provide technical support to Subscriber through Crossref’s existing support channels as requested by Subscriber, and will provide a response within one (1) business day to support requests received during normal working hours in the United States and the United Kingdom. “Business days” do not include weekends or legal holidays in the United States and the United Kingdom. “Response” means that support requests will be acknowledged. The time required for resolution will depend upon the nature of the request.
Learn more about the Metadata Plus service terms, and fees and pricing tiers for Metadata Plus.
Learn more about Metadata Plus in our documentation.
