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.
Within a folder, the Documents tab shows all the submitted documents for that folder.
Each document submitted generates a Similarity Report after the document has been through the Similarity Check. If more documents are present than can be displayed at once, the pages feature will appear beneath the documents - click the page number to display, or click Next to move to the next page of documents.
zip file upload - to submit a zip file containing multiple documents, up to a maximum of 100MB or 1,000 files. Larger files may take longer to upload
cut & paste - to submit text directly into the submission box. Use this to copy and paste a submission from a file format that is not supported. This method supports plain text only (no images or non-text information)
iThenticate currently accepts the following file types for document upload:
Microsoft Word® (.doc and .docx)
Word XML
plain text (.txt)
Adobe PostScript®
Portable Document Format (.pdf)
HTML
Corel WordPerfect® (.wpd)
Rich Text Format (.rtf)
Each file may not exceed 400 pages, and each file size may not exceed 100 MB. Reduce the size of larger files by removing non-text content. You can’t upload or submit to iThenticate files that are password-protected, encrypted, hidden, system files, or read-only.
.pdf documents must contain text - if they contain only images of text, they will be rejected during the upload attempt. To check, copy and paste a section of the .pdf into a plain-text editor such as Microsoft Notepad® or Apple TextEdit®. If no text is copied over, the selection does not contain text.
To convert scanned images of a document, or an image saved as a .pdf, use Optical Character Recognition (OCR) software to convert the image to text. The conversion software can introduce errors, so manually check and correct the converted document.
Some document formats can contain multiple data types, such as text, images, embedded information from another file, and formatting. Non-text information that is not saved directly within the document will not be included in a file upload, for example, references to a Microsoft Excel® spreadsheet included within a Microsoft Office Word® document.
Use a word-processing program to save your file as one of the accepted types listed above, such as .rtf or .txt. Neither file type supports images or non-text data within the file. Plain text format does not support any formatting, and rich text format allows only limited formatting.
When converting a file to a new format, save it with a different name from the original, to avoid accidentally overwriting the original file. This is especially important when converting to plain text or rich text formats, to prevent permanent loss of the original formatting or image content of the file.
Page maintainer: Kathleen Luschek Last updated: 2020-May-19
