Our REST API makes all of the metadata we hold publicly available. It receives the majority of our API traffic, with around 1 billion hits per month. It’s one of the key ways that we fulfil our mission to make research objects easy to find, cite, link, assess, and reuse. From 1 December 2025, we will be revising the rate limits for the public and polite pools of the REST API to ensure that we can maintain a stable and reliable system, and that metadata is freely available to everyone.
Noyam Journals, based in Accra, Ghana, was recently recognised for the completeness of its metadata through the Crossref Metadata Award, part of our 25th anniversary celebrations. Noyam was one of six publishers worldwide to receive the award and stood out as a leader among members of our Global Equitable Membership (GEM) Program.
Wednesday 22nd October 2025—Crossref, the open scholarly infrastructure nonprofit, today releases an enhanced dashboard showing metadata coverage and individual organisations’ contributions to documenting the process and outputs of scientific research in the open. The tool helps research-performing, funding, and publishing organisations identify gaps in open research information, and provides supporting evidence for movements like the Barcelona Declaration for Open Research Information, which encourages more substantial commitment to stewarding and enriching the scholarly record through open metadata.
Welcome back to our series of case studies of research funders using the Grant Linking System. In this interview, I talk with Cátia Laranjeira, PTCRIS Program Manager at FCCN|FCT, Portugal’s main public funding agency, about the agency’s approach to metadata, persistent identifiers, Open Science and Open Infrastructure.
With a holistic approach to the management, production and access to information on science, FCCN|FCT’s decision to implement the Grant Linking System within their processes was not simply a technical upgrade, but a coordinated effort to continue building a strong culture of openness. With the mantra “register once, reuse always”, FCCN|FCT efforts to embrace open funding metadata was only logical.
Content Registration allows members to register and update metadata via machine or human interfaces.
When you join Crossref as a member you are issued a DOI prefix. You combine this with a suffix of your choice to create a DOI, which becomes active once registered with Crossref. Content Registration allows members to register a DOI and deposit or update its associated metadata, via machine or human interfaces.
Benefits of content registration
Academic and professional research travels further if it’s linked to the millions of other published papers. Crossref members register content with us to let the world know it exists, instead of creating thousands of bilateral agreements.
Members send information called metadata to us. Metadata includes fields like dates, titles, authors, affiliations, funders, and online location. Each metadata record includes a persistent identifier called a digital object identifier (DOI) that stays with the work even if it moves websites. Though the DOI doesn’t change, its associated metadata is kept up-to-date by the owner of the record.
Richer metadata makes content useful and easier to find. Through Crossref, members are distributing their metadata downstream, making it available to numerous systems and organisations that together help credit and cite the work, report impact of funding, track outcomes and activity, and more.
Members maintain and update metadata long-term, telling us if content moves to a new website, and they include more information as time goes on. This means that there is a growing chance that content is found, cited, linked to, included in assessment, and used by other researchers.
Participation Reports give a clear picture for anyone to see the metadata Crossref has. See for yourself where the gaps are, and what our members could improve upon. Understand best practice through seeing what others are doing, and learn how to level-up.
This is Crossref infrastructure. You can’t see infrastructure, yet research—and researchers all over the world—rely on it.
To register content with Crossref, you need to be a member. You’ll use one of our content registration methods to give us metadata about your content. Note that you don’t send us the content itself - you create a metadata record that links persistently (via a persistent identifier) to the content on your site or hosting platform. Learn more about metadata, constructing your DOIs, and ways to register your content.
You should assign Crossref DOIs to and register content for anything that is likely to be cited in the scholarly literature.
What types of resources and records can be registered with Crossref?
We are working to make our input schema more flexible so that almost any type of object can be registered and distributed openly through Crossref. At the moment, members tend to register the following:
Conference proceedings: information about a single conference and records for each conference paper/proceeding.
Datasets: includes database records or collections.
Dissertations: includes single dissertations and theses, but not collections.
Grants: includes both direct funding and other types of support such as the use of equipment and facilities.
Journals and articles: at the journal title and article level, and includes supplemental materials as components.
Peer reviews: any number of reviews, reports, or comments attached to any other work that has been registered with Crossref.
Pending publications: a temporary placeholder record with minimal metadata, often used for embargoed work where a DOI needs to be shared before the full content is made available online.
Preprints and posted content: includes preprints, eprints, working papers, reports, and other types of content that has been posted but not formally published.
You pay a one-time content registration fee for each content item you register with us. content registration fees are different for different types of content and sometimes include volume discounts for large batches or backfile material. You don’t pay to update an existing metadata record. It’s an obligation of membership that you maintain your metadata for the long term, including updating any URLs that change. In addition, we warmly encourage you to correct and add to your metadata, and there is no charge for redepositing (updating) existing metadata. Learn more about maintaining your metadata, and managing existing DOIs.
Your content registration fees are billed quarterly in arrears. This means you’ll usually receive a bill at the beginning of each quarter for the content you registered in the previous quarter. The only exception is if you’ve only registered a small number of DOIs.
