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Since we first launched our REST API around 2013 as a Labs project, it has evolved well beyond a prototype into arguably Crossref’s most visible and valuable service. It is the result of 20,000 organisations around the world that have worked for many years to curate and share metadata about their various resources, from research grants to research articles and other component inputs and outputs of research. The REST API is relied on by a large part of the research information community and beyond, seeing around 1.

This year’s public data file is now available, featuring over 156 million metadata records deposited with Crossref through the end of April 2024 from over 19,000 members. A full breakdown of Crossref metadata statistics is available here. Like last year, you can download all of these records in one go via Academic Torrents or directly from Amazon S3 via the “requester pays” method. Download the file: The torrent download can be initiated here.

Subject classifications have been available via the REST API for many years but have not been complete or reliable from the start and will soon be deprecated. dfdfd The subject metadata element was born out of a Labs experiment intended to enrich the metadata returned via Crossref Metadata Search with All Subject Journal Classification codes from Scopus. This feature was developed when the REST API was still fairly new, and we now recognize that the initial implementation worked its way into the service prematurely.

We have some exciting news for fans of big batches of metadata: this year’s public data file is now available. Like in years past, we’ve wrapped up all of our metadata records into a single download for those who want to get started using all Crossref metadata records. We’ve once again made this year’s public data file available via Academic Torrents, and in response to some feedback we’ve received from public data file users, we’ve taken a few additional steps to make accessing this 185 gb file a little easier.

In 2020 we released our first public data file, something we’ve turned into an annual affair supporting our commitment to the Principles of Open Scholarly Infrastructure (POSI). We’ve just posted the 2022 file, which can now be downloaded via torrent like in years past. We aim to publish these in the first quarter of each year, though as you may notice, we’re a little behind our intended schedule. The reason for this delay was that we wanted to make critical new metadata fields available, including resource URLs and titles with markup.

UPDATE, 24 August 2021: All pools have been migrated to the new Elasticsearch-backed API, which already appears to be more stable and performant than the outgoing Solr API. Please report any issues via our Crossref issue repository in Gitlab. UPDATE, 9 August 2021: The cutovers for the polite and Plus pools are delayed again. We’re still working to ensure acceptable performance and stability before serving responses from the new application and infrastructure.