# Interfaces for Machines **URL:** https://community.crossref.org/c/metadata-retrieval/interfaces-for-machines/29.md [Latest](https://community.crossref.org/latest.md) · [Categories](https://community.crossref.org/categories.md) · [Tags](https://community.crossref.org/tags.md) --- ## [About the Interfaces for Machines category](https://community.crossref.org/t/about-the-interfaces-for-machines-category/1299)
**Author:** [@Vanessa](https://community.crossref.org/u/Vanessa)\ **Replies:** 0
There are APIs for machines (to look up metadata records or DOIs in volume), including: REST API, XML API, OAI-PMH, and OpenURL. API name Description REST API The REST API outputs in JSON and enables sophisticat… --- ## [Issue adding new data citations](https://community.crossref.org/t/issue-adding-new-data-citations/16716)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 1\ **Last updated:** [30 October 2026 10:49 UTC](https://community.crossref.org/t/issue-adding-new-data-citations/16716 "2026-10-30T10:49:01Z")
Since 23 October 2026, we have not added new data citations. This is due to a bug in the data collection and filtering which we will be looking to fix in the coming days. Access to the data citations API is not affected.… --- ## [Changes to the Metadata Plus rate limits and monthly snapshot format](https://community.crossref.org/t/changes-to-the-metadata-plus-rate-limits-and-monthly-snapshot-format/16712)
**Author:** [@lmontilla](https://community.crossref.org/u/lmontilla)\ **Replies:** 0\ **Last updated:** [29 October 2026 11:16 UTC](https://community.crossref.org/t/changes-to-the-metadata-plus-rate-limits-and-monthly-snapshot-format/16712 "2026-10-29T11:16:43Z")
As part of our efforts to keep Crossref systems stable and scalable for the community, we will be adjusting the rate limits available under the Metadata Plus subscription. The changes will be implemented from 1 February … --- ## [Update to content negotiation CSL styles](https://community.crossref.org/t/update-to-content-negotiation-csl-styles/16606)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [19 October 2026 10:35 UTC](https://community.crossref.org/t/update-to-content-negotiation-csl-styles/16606 "2026-10-19T10:35:26Z")
Content negotiation at Crossref makes use of the library of styles curated by the Citation Style Language (CSL) community. We periodically update these styles to use the latest CSL library, and will be making the next up… --- ## [Continuing the Data Citations API endpoint in beta format](https://community.crossref.org/t/continuing-the-data-citations-api-endpoint-in-beta-format/16404)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [18 September 2026 13:04 UTC](https://community.crossref.org/t/continuing-the-data-citations-api-endpoint-in-beta-format/16404 "2026-09-18T13:04:14Z")
Six months ago, we launched an API endpoint for data citations. We said we’d give an update on progress after half a year, and here it is. The headline is that we won’t be making any big changes yet and will keep it runn… --- ## [Get and sync all Crossref metadata](https://community.crossref.org/t/get-and-sync-all-crossref-metadata/15562)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 2\ **Last updated:** [8 September 2026 14:43 UTC](https://community.crossref.org/t/get-and-sync-all-crossref-metadata/15562 "2026-09-08T14:43:42Z")
Would you like to have all Crossref metadata? No problem! You can. There are a few questions you might want to ask yourself first, and below we look at how you can get your hands on it. First, why do we give our data aw… --- ## [Our monthly JSON snapshot is smaller, and that's a good thing](https://community.crossref.org/t/our-monthly-json-snapshot-is-smaller-and-thats-a-good-thing/16348)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [4 September 2026 16:11 UTC](https://community.crossref.org/t/our-monthly-json-snapshot-is-smaller-and-thats-a-good-thing/16348 "2026-09-04T16:11:31Z")
The JSON snapshot generated for Metadata Plus users is around 20 GB smaller than last months. Uncompressed, it is larger than last months and contains all of the latest metadata. So, what happened? We recently made an u… --- ## [Changes to cursors, filtering, and sorting in the REST API](https://community.crossref.org/t/changes-to-cursors-filtering-and-sorting-in-the-rest-api/16246)
**Author:** [@lmontilla](https://community.crossref.org/u/lmontilla)\ **Replies:** 3\ **Last updated:** [24 August 2026 13:06 UTC](https://community.crossref.org/t/changes-to-cursors-filtering-and-sorting-in-the-rest-api/16246 "2026-08-24T13:06:40Z")
On Monday 17 August 2026 24 August 2026, we will upgrade the Elasticsearch version used by our REST API. This is part of our regular maintenance of services and most users will not see any difference, however there are s… --- ## [ROR filters for affiliations and funders in the REST API](https://community.crossref.org/t/ror-filters-for-affiliations-and-funders-in-the-rest-api/16222)
**Author:** [@lmontilla](https://community.crossref.org/u/lmontilla)\ **Replies:** 0\ **Last updated:** [3 August 2026 08:42 UTC](https://community.crossref.org/t/ror-filters-for-affiliations-and-funders-in-the-rest-api/16222 "2026-08-03T08:42:52Z")
In this post, we bring you an update to the REST API filters you can use. As of August 3 2026, you will be able to use has-affiliation-ror-id and has-funder-ror-id to return only works with ROR IDs in the affiliation or … --- ## [Refining REST API limits for improved stability and reliability](https://community.crossref.org/t/refining-rest-api-limits-for-improved-stability-and-reliability/16137)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 1\ **Last updated:** [21 July 2026 12:14 UTC](https://community.crossref.org/t/refining-rest-api-limits-for-improved-stability-and-reliability/16137 "2026-07-21T12:14:48Z")
From today, 21 July 2026, we will be implementing changes to REST API limits to better reflect different types of REST API requests. This is a continuation of changes we started late last year. Many downstream systems a… --- ## [How to create a local list of API requests with Bruno](https://community.crossref.org/t/how-to-create-a-local-list-of-api-requests-with-bruno/15878)
**Author:** [@lmontilla](https://community.crossref.org/u/lmontilla)\ **Replies:** 0\ **Last updated:** [28 May 2026 14:26 UTC](https://community.crossref.org/t/how-to-create-a-local-list-of-api-requests-with-bruno/15878 "2026-05-28T14:26:27Z")
If you would like to have quick access to a customized list of API requests or want a faster way to test the REST API locally, there are several options. We have been experimenting with an open source API client called B… --- ## [Roles appearing in the REST API and fix for peer reviewers](https://community.crossref.org/t/roles-appearing-in-the-rest-api-and-fix-for-peer-reviewers/15846)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [22 May 2026 09:33 UTC](https://community.crossref.org/t/roles-appearing-in-the-rest-api-and-fix-for-peer-reviewers/15846 "2026-05-22T09:33:00Z")
In preparation for some upcoming schema changes, we have added a new field to records in the REST API. Authors, editors, translators, and contributors will have a ‘role’ field. We will make an announcement in the coming … --- ## [Updates to CSL reference styles](https://community.crossref.org/t/updates-to-csl-reference-styles/15673)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 9\ **Last updated:** [23 April 2026 18:35 UTC](https://community.crossref.org/t/updates-to-csl-reference-styles/15673 "2026-04-23T18:35:46Z")
Later today we will update the reference styles used by content negotiation. The content negotiation service enables single metadata records to be retrieved in a variety of formats, including formatted consistently with … --- ## [UNIXREF XML API inserting incorrect whitespace between HTML-like elements](https://community.crossref.org/t/unixref-xml-api-inserting-incorrect-whitespace-between-html-like-elements/14539)
**Author:** [@castedo](https://community.crossref.org/u/castedo)\ **Replies:** 4\ **Last updated:** [19 March 2026 15:12 UTC](https://community.crossref.org/t/unixref-xml-api-inserting-incorrect-whitespace-between-html-like-elements/14539 "2026-03-19T15:12:18Z")
This topic is related to topic #14533 which is a question specifically about the REST JSON API. My question here is specifically about a different problem in the UNIXREF XML API, as used by Zotero, via the HTTP endpoint… --- ## [REST API pools: Which to use and when?](https://community.crossref.org/t/rest-api-pools-which-to-use-and-when/15317)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [23 February 2026 15:58 UTC](https://community.crossref.org/t/rest-api-pools-which-to-use-and-when/15317 "2026-02-23T15:58:52Z")
What are the differences between the public, polite, and plus API pools? You may have seen that we have three different pools for accessing metadata, depending on whether you authenticate and how much information you gi… --- ## [Date types in the REST API](https://community.crossref.org/t/date-types-in-the-rest-api/15118)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [16 January 2026 10:04 UTC](https://community.crossref.org/t/date-types-in-the-rest-api/15118 "2026-01-16T10:04:20Z")
“I’d like to get all the articles from publisher X in March 2023”. That’s a fairly typical question you might start out with when you come to look at Crossref metadata. What you’ll quickly realise is that ‘in March 2023’… --- ## [Updates to REST API rate limits](https://community.crossref.org/t/updates-to-rest-api-rate-limits/14872)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [2 December 2025 15:25 UTC](https://community.crossref.org/t/updates-to-rest-api-rate-limits/14872 "2025-12-02T15:25:31Z")
We have updated the rate limits in the REST API, as outlined in a recent blog post. This will ensure that we can keep the API and the data available for everyone, and is one a series of changes we’ve been looking at to … --- ## [A way, per DOI, to get original metadata deposit XML?](https://community.crossref.org/t/a-way-per-doi-to-get-original-metadata-deposit-xml/14529)
**Author:** [@castedo](https://community.crossref.org/u/castedo)\ **Replies:** 6\ **Last updated:** [29 September 2025 18:46 UTC](https://community.crossref.org/t/a-way-per-doi-to-get-original-metadata-deposit-xml/14529 "2025-09-29T18:46:34Z")
My motivation for asking is trying to make sense of the different XML that is returned by UNIXREF API results vs JSON API results. Specifically for DOI 10.1371/journal.pgen.1009241 I see the following JSON value for the … --- ## [Authenticated-orcid](https://community.crossref.org/t/authenticated-orcid/14380)
**Author:** [@nick](https://community.crossref.org/u/nick)\ **Replies:** 1\ **Last updated:** [2 September 2025 22:27 UTC](https://community.crossref.org/t/authenticated-orcid/14380 "2025-09-02T22:27:09Z")
A colleague of mine published an article which showed up in crossref with the author property “authenticated-orcid” as false. She received a Crossref email asking permission to add the publication to orcid, but before an… --- ## [What's going on with the REST API? Indexing issues](https://community.crossref.org/t/whats-going-on-with-the-rest-api-indexing-issues/14341)
**Author:** [@mrittman](https://community.crossref.org/u/mrittman)\ **Replies:** 0\ **Last updated:** [20 August 2025 15:51 UTC](https://community.crossref.org/t/whats-going-on-with-the-rest-api-indexing-issues/14341 "2025-08-20T15:51:49Z")
If you’ve checked our status page recently, you’ll have seen that we’ve been having issues indexing deposited metadata in our REST API. That’s caused delays and confusion for some of our members, and frustration for user… --- ## [Invalid CSL-JSON record types](https://community.crossref.org/t/invalid-csl-json-record-types/14332)
**Author:** [@larsgw](https://community.crossref.org/u/larsgw)\ **Replies:** 1\ **Last updated:** [19 August 2025 14:40 UTC](https://community.crossref.org/t/invalid-csl-json-record-types/14332 "2025-08-19T14:40:45Z")
I’ve encountered a few invalid CSL-JSON records returned by the REST API: 10.33915/datasets.1 (https://api.crossref.org/works/10.33915/datasets.1) (type database) returns an invalid CSL-JSON record with "type" set to n… --- ## [Search by ORCiD - incomplete results](https://community.crossref.org/t/search-by-orcid-incomplete-results/13531)
**Author:** [@lukasW](https://community.crossref.org/u/lukasW)\ **Replies:** 2\ **Last updated:** [16 May 2025 16:33 UTC](https://community.crossref.org/t/search-by-orcid-incomplete-results/13531 "2025-05-16T16:33:50Z")
Dear all, We are using crossref to update a publication list on a research group webpage - by searching for publications by members ORCiDs. That generally works beautifully, yet there are some ommissions that are hard t… --- ## [Missing DOIs/articles in OAI-PMH results](https://community.crossref.org/t/missing-dois-articles-in-oai-pmh-results/4124)
**Author:** [@dbourget](https://community.crossref.org/u/dbourget)\ **Replies:** 5\ **Last updated:** [13 March 2025 22:01 UTC](https://community.crossref.org/t/missing-dois-articles-in-oai-pmh-results/4124 "2025-03-13T22:01:23Z")
Hi, Some results that can be found using CrossRef’s web search cannot be found via OAI-PMH. For example this record: 10.1215/00318108-10294409 Is found among the first pages of results for ISSN 0031-8108 when ordering… --- ## [Ticket of the month - December 2024 - Retraction Watch Tips](https://community.crossref.org/t/ticket-of-the-month-december-2024-retraction-watch-tips/12991)
**Author:** [@Shayn](https://community.crossref.org/u/Shayn)\ **Replies:** 0\ **Last updated:** [9 January 2025 17:50 UTC](https://community.crossref.org/t/ticket-of-the-month-december-2024-retraction-watch-tips/12991 "2025-01-09T17:50:54Z")
Hello, and Happy New Year, Crossref community! A little over a year ago, Crossref acquired the Retraction Watch database via an agreement with The Center for Scientific Integrity, the organization behind the Retraction … --- ## [Overlap between different services providing citation data](https://community.crossref.org/t/overlap-between-different-services-providing-citation-data/2994)
**Author:** [@pschloss](https://community.crossref.org/u/pschloss)\ **Replies:** 5\ **Last updated:** [23 December 2024 17:53 UTC](https://community.crossref.org/t/overlap-between-different-services-providing-citation-data/2994 "2024-12-23T17:53:54Z")
Hello - I’m looking for an open source of data for the number of citations and so am very excited to use Crossref. I’m curious if there is data somewhere that shows the number or fraction of publishers/journals/papers in… --- ## [Advanced set/boolean operators](https://community.crossref.org/t/advanced-set-boolean-operators/4596)
**Author:** [@joshuasy10](https://community.crossref.org/u/joshuasy10)\ **Replies:** 2\ **Last updated:** [18 November 2024 20:09 UTC](https://community.crossref.org/t/advanced-set-boolean-operators/4596 "2024-11-18T20:09:11Z")
Is there any functionality to do OR and NOT operations when doing a search query with the /get/works endpoint? eg. something like ( ALL(zebrafish) AND ALL(pesticides) AND ( ALL(behaviour) OR ALL(behavior) ) AND NOT … --- ## [DOIs not found when using query batch deposits](https://community.crossref.org/t/dois-not-found-when-using-query-batch-deposits/6088)
**Author:** [@benselme](https://community.crossref.org/u/benselme)\ **Replies:** 3\ **Last updated:** [27 June 2024 15:50 UTC](https://community.crossref.org/t/dois-not-found-when-using-query-batch-deposits/6088 "2024-06-27T15:50:55Z")
We are trying to link our articles’ references using query batch deposits. Unfortunately, this method seems to be unable to resolve very obvious citations that other methods easily find DOIs for. For example, if we uplo… --- ## [Polite API slow](https://community.crossref.org/t/polite-api-slow/5796)
**Author:** [@thewilkybarkid](https://community.crossref.org/u/thewilkybarkid)\ **Replies:** 4\ **Last updated:** [10 June 2024 09:57 UTC](https://community.crossref.org/t/polite-api-slow/5796 "2024-06-10T09:57:55Z")
There’s currently an open incident with the public API, which seems to have been resolved though it’s still marked as ‘degraded performance’. (The forum doesn’t seem to let me include links for some reason, so: https://s… --- ## [Rebalancing our REST API traffic - Crossref](https://community.crossref.org/t/rebalancing-our-rest-api-traffic-crossref/5863)
**Author:** [@Crossref](https://community.crossref.org/u/Crossref)\ **Replies:** 0\ **Last updated:** [4 June 2024 21:45 UTC](https://community.crossref.org/t/rebalancing-our-rest-api-traffic-crossref/5863 "2024-06-04T21:45:14Z")
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 w… --- ## [Getting referenced-by works from a DOI with beta/relationships?](https://community.crossref.org/t/getting-referenced-by-works-from-a-doi-with-beta-relationships/5718)
**Author:** [@Karo](https://community.crossref.org/u/Karo)\ **Replies:** 3\ **Last updated:** [29 May 2024 18:29 UTC](https://community.crossref.org/t/getting-referenced-by-works-from-a-doi-with-beta-relationships/5718 "2024-05-29T18:29:43Z")
Hello, I am interested in retrieving a list of works which have referenced specific dois. I am aware of the is-reference-by-count return in the production API, but is it possible to retrieve the list of works instead o… [Next page](https://community.crossref.org/c/metadata-retrieval/interfaces-for-machines/29.md?page=1)