The Frankfurt Book Fair is the largest book fair in the world, and therefore a key event on our calendar. Held annually in Frankfurt, Germany, the 77th Frankfurt Book Fair (October 15–19, 2025) saw 118,000 trade visitors and 120,000 private visitors from 131 countries. The Crossref booth was located, as usual, in Hall 4.0 where all the stands with information about academic publishing can be found. Four Crossref colleagues attended the Book Fair this year, and in this blog post, you can read more about their meetings, experiences, and plans.
TL;DR. Metadata Manager will be retired at the end of 2025. Over the past four years, we have been developing a new helper tool to replace it, and that tool has now reached a stage of maturity that means we will be able to switch off Metadata Manager by the end of the year.
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.
Members can participate in Cited-by by completing the following steps:
Deposit references for one or more prefixes as part of your content registration process. Use your Participation Report to see your progress with depositing references. This step is not mandatory, but highly recommended to ensure that your citation counts are complete.
We will match the metadata in the references to DOIs to establish Cited-by links in the database. As new content is registered, we automatically update the citations and, for those members with Cited-by alerts enabled, we notify you of the new links.
Display the links on your website. We recommend displaying citations you retrieve on DOI landing pages, for example:
If you are a member through a Sponsor, you may have access to Cited-by through your sponsor – please contact them for more details. OJS users can use the Cited-by plugin. If you need more help, you can learn more from PKP’s Cited-by (OJS Scopus/Crossref plugin) - as of OJS 3.2, this third-party plugin allows journals to display citations and citation counts (using article DOIs) from Scopus and/or Crossref.
Citation matching
Members sometimes submit references without including a DOI tag for the cited work. When this happens, we look for a match based on the metadata provided. If we find one, the reference metadata is updated with the DOI and we add the "doi-asserted-by": "crossref" tag. If we don’t find a match immediately, we will try again at a later date.
There are some references for which we won’t find matches, for example where a DOI has been registered with an agency other than Crossref (such as DataCite) or if the reference refers to an object without a DOI, including conferences, manuals, blog posts, and some journals’ articles.
To perform matching, we first check if a DOI tag is included in the reference metadata. If so, we assume it is correct and link the corresponding work. If there isn’t a DOI tag, we perform a search using the metadata supplied and select candidate results by thresholding. The best match is found through a further validation process. Learn more about how we match references. The same process is used for the results shown on our Simple Text Query tool.
All citations to a work are returned in the corresponding Cited-by query.
Page maintainer: Isaac Farley Last updated: 2023-April-28
