Crossref was created back in 2000 by 12 forward-thinking scholarly publishers from North America and Europe, and by 2002, these members had registered 4 million DOI records. At the time of writing, we have over 23,600 members in 164 different countries. Half of our members are based in Asia, and 35% are universities or scholar-led. These members have registered over 176 million open metadata records with DOIs (as of today). What a difference 25 years makes!
In our 25th anniversary year, I thought it would be time to take a look at how we got here. And so—hold tight—we’re going to go on an adventure through space and time1, stopping every 5 years through Crossref history to check in on our members. And we’re going to see some really interesting changes over the years.
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.Â
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.
To work out which version you’re on, take a look at the website address that you use to access iThenticate. If you go to ithenticate.com then you are using v1. If you use a bespoke URL, https://crossref-[your member ID].turnitin.com/ then you are using iThenticate 2.0.
Use doc-to-doc comparison to compare a primary uploaded document with up to five comparison uploaded documents. Any documents that you upload to doc-to-doc comparison will not be indexed and will not be searchable against any future submissions.
Uploading a primary document to doc-to-doc comparison will cost you a single document submission, but the comparison documents uploaded will not cost you any submissions.
Start from Folders, go to the Submit a document menu, and click Doc-to-Doc Comparison.
The doc-to-doc comparison screen allows you to choose one primary document and up to five comparison documents. Choose the destination folder for the documents you will upload. The Similarity Report for the comparison will be added to the same folder.
For your primary document, provide the author’s first name, last name, and document title. If you do not provide these details, the filename will be used for the title, and the author details will stay blank.
If you have administrator permissions, you can assign the Similarity Report for the comparison to a reporting group by selecting one from the Reporting Group drop-down. Learn more about reporting groups.
Click Choose File, and select the file you want to upload as your primary document. See the file requirements for both the primary and comparison documents on the right of the screen.
You can choose up to five comparison documents to check against your primary document. These do not need to be given titles and author details. Each of the filenames must be unique. Click Choose Files, and select the files you would like to upload as comparison documents. To remove a file from the comparison before you upload it, click the X icon next to the file. To upload your files for comparison, click Upload.
Once your document has been uploaded and compared against the comparison documents, it will appear in your chosen destination folder.
This upload will have ‘Doc-to-Doc Comparison’ beneath the document title to show that this is a comparison upload and has not been indexed.
The upload will be given a Similarity Score against the selected comparison documents, which is also displayed in the report column. Click the similarity percentage to open the doc-to-doc comparison in the Document Viewer.
The Document Viewer is separated into three sections:
Along the top of the screen, the paper information bar shows details about the primary document, including document title, author, date the report was processed, word count, number of comparison documents provided, and how many of those documents matched with the primary document.
On the left panel is the paper text - this is the text of your primary document. Matching text is highlighted in red.
Your comparison documents will appear in the sources panel to the right, showing instances of matching text within the submitted documents.
By default, the doc-to-doc comparison will open the Document Viewer in the All Sources view. This view lists all the comparison documents you uploaded. Each comparison document has a percentage showing the amount of content within them that is similar to the primary document. If a comparison document has no matching text with the primary document, it has 0% next to it.
Doc-to-doc comparison can also be viewed in Match Overview mode. In this view, the comparison documents are listed with highest match percentage first, and all the sources are shown together, color-coded, on the paper text.
Page maintainer: Kathleen Luschek Last updated: 2020-May-19
