Using HTTPS to query
Most queries sent to our XML API will use HTTPS. For HTTPS querying you need to add either your Crossref member account credentials or an email address in the query. Use a DOI-to-metadata query when you know the DOI and want to find its associated metadata.
HTTPS query examples
https://doi.crossref.org/servlet/query?pid={email@address.com}&id=10.1577/H02-043
https://doi.crossref.org/servlet/query?pid={email@address.com}&format=unixsd**&id=10.1577/H02-043
https://doi.crossref.org/search/doi?pid={email@address.com}&doi=10.1577/H02-043
XML query
https://doi.crossref.org/servlet/query?usr={email@address.com}&format=unixref&qdata=<?xml version="1.0"?><query_batch version="2.0"...
where:
- usr or pid is your email address
- format is the desired results format
- qdata is the query data (XML is the recommended format)
- id is a Crossref DOI
XML querying
An XML query must contain complete and valid query XML. Multiple queries may be included in a single XML file, but the <query> element is repeatable. For best results, do not exceed 5 queries per HTTPS XML query request.
Multiple queries in a single request
https://doi.crossref.org/servlet/query?usr=username&pwd=password&qdata=<?xml version = "1.0" encoding="UTF-8"?>
<query_batch xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xmlns="http://www.crossref.org/qschema/2.0" xsi:schemaLocation="http://www.crossref.org/qschema/2.0 http://www.crossref.org/qschema/crossref_query_input2.0.xsd"><head><email_address>support@crossref.org</email_address><doi_batch_id>ABC_123_fff</doi_batch_id> </head> <body> <query key="query1" enable-multiple-hits="true" forward-match="false"><issn match="optional">15360075</issn><journal_title match="exact">American Journal of Bioethics</journal_title><author match="fuzzy" search-all-authors="false">Agich</author><volume match="fuzzy">1</volume><issue>1</issue><first_page>50</first_page><year>2001</year><article_title>The Salience of Narrative for Bioethics</article_title></query><query key="query2" enable-multiple-hits="true"><unstructured_citation>Hungate, B. A., & Hampton, H. M. (2012). Ecosystem services: Valuing ecosystems for climate. Nature Climate Change, 2(3), 151-152.</unstructured_citation></query></body></query_batch>
HTTPS XML query example
https://doi.crossref.org/servlet/query?usr=email@address.com&qdata=<?xml version = "1.0" encoding="UTF-8"?>
<query_batch xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xmlns="http://www.crossref.org/qschema/2.0" xsi:schemaLocation="http://www.crossref.org/qschema/2.0 http://www.crossref.org/qschema/crossref_query_input2.0.xsd"><head><email_address>support@crossref.org</email_address><doi_batch_id>ABC_123_fff</doi_batch_id> </head> <body> <query key="1178517" enable-multiple-hits="false" forward-match="false"><issn match="optional">15360075</issn><journal_title match="exact">American Journal of Bioethics</journal_title><author match="fuzzy" search-all-authors="false">Agich</author><volume match="fuzzy">1</volume><issue>1</issue><first_page>50</first_page><year>2001</year><article_title>The Salience of Narrative for Bioethics</article_title></query></body></query_batch>
Learn more about querying with an unstructured (formatted) citation
https://doi.crossref.org/servlet/query?usr=email@address.com&format=unixref&qdata=<?xml version = "1.0" encoding="UTF-8"?><query_batch xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xmlns="http://www.crossref.org/qschema/2.0" xsi:schemaLocation="http://www.crossref.org/qschema/2.0 http://www.crossref.org/qschema/crossref_query_input2.0.xsd"><head><email_address>your@email.org</email_address><doi_batch_id>01032012</doi_batch_id></head><body><query key="q1" enable-multiple-hits="true"><unstructured_citation>Hungate, B. A., & Hampton, H. M. (2012). Ecosystem services: Valuing ecosystems for climate. Nature Climate Change, 2(3), 151-152.</unstructured_citation></query></body></query_batch>
HTTPS XML query with URL encoding
https://doi.crossref.org/servlet/query?usr=email@address.com&qdata=%3C?xml%20version=%221.0%22?%3E%3Cquery_batch%20version=%222.0%22%20xsi:schemaLocation=%22https://www.crossref.org/qschema/2.0%20https://www.crossref.org/qschema/crossref_query_input2.0.xsd%22%20xmlns=%22https://www.crossref.org/qschema/2.0%22%20xmlns:xsi=%22http://www.w3.org/2001/XMLSchema-instance%22%3E%3Chead%3E%3Cemail_address%3Esupport@crossref.org%3C/email_address%3E%3Cdoi_batch_id%3EABC_123_fff%3C/doi_batch_id%3E%20%3C/head%3E%20%3Cbody%3E%20%3Cquery%20key=%221178517%22%20enable-multiple-hits=%22false%22%20forward-match=%22false%22%3E%3Cissn%20match=%22optional%22%3E15360075%3Cissn%3Cjournal_title%20match=%22exact%22%3EAmerican%20Journal%20of%20Bioethics%3C/journal_title%3E%3Cauthor%20match=%22fuzzy%22%20search-all-authors=%22false%22%3EAgich%3C/author%3E%3Cvolume%20match=%22fuzzy%22%3E1%3C/volume%3E%3Cissue%3E1%3C/issue%3E%3Cfirst_page%3E50%3C/first_page%3E%3Cyear%3E2001%3C/year%3E%3Carticle_title%3EThe%20Salience%20of%20Narrative%20for%20Bioethics%3C/article_title%3E%3C/query%3E%3C/body%3E%3C/query_batch%
Note that some characters must be URL-encoded:
| Character | Name | URL code |
|---|
| ; | Semi-colon | %3B |
| / | Slash, virgule, separatrix, or solidus | %2F |
| ? | Question mark | %3F |
| : | Colon | %3A |
| @ | At sign, arobase | %40 |
| = | Equals sign | %3D |
| & | Ampersand | %26 |
| lf | line feed | %0A |
