Filters narrow your results to entities matching specific conditions. Use the filter parameter with attribute-value pairs:
filter=attribute:value,attribute2:value2
Filters are case-insensitive.
Examples Works by type
Authors by ORCID status
Sources with many works
curl "https://api.openalex.org/works?filter=type:book"
Logical expressions Inequality For numerical filters, use < and > for inequalities:
# Sources hosting more than 1000 works https://api.openalex.org/sources?filter =works_count: > 1000
Some attributes have convenience filters like from_publication_date and to_publication_date:
# Works published between Jan 1-26, 2022 https://api.openalex.org/works?filter =from_publication_date:2022-01-01,to_publication_date:2022-01-26
Negation (NOT) Prepend ! to negate any filter:
# All institutions except those in the US https://api.openalex.org/institutions?filter =country_code:!us
Intersection (AND) Comma-separated filters are combined with AND:
# Works cited more than once AND open access https://api.openalex.org/works?filter =cited_by_count: > 1,is_oa: true
For AND within a single attribute, repeat the filter or use +:
Repeating filters
Using + symbol
# Works with authors from France AND UK https://api.openalex.org/works?filter =institutions.country_code:fr,institutions.country_code:gb
The + syntax doesn’t work for search filters, boolean filters, or numeric filters.
Addition (OR) Use the pipe | to match any of multiple values:
# Works with authors from France OR UK https://api.openalex.org/works?filter =institutions.country_code:fr | gb
This is efficient for retrieving many records by ID at once:
# Get two works by DOI in one request https://api.openalex.org/works?filter =doi:https://doi.org/10.1371/journal.pone.0266781 | https://doi.org/10.1371/journal.pone.0267149
OR limit: You can combine up to 100 values with | in a single filter. Use per_page=100 to get all results.
OR works within a filter, not between filters. This will return an error:# INVALID: OR between different filters https://api.openalex.org/works?filter =institutions.country_code:fr | primary_location.source.issn:0957-1558
Available filters by entity Each entity type has its own set of filterable fields. See the API reference for complete filter lists:
Entity Filters Works publication_year, type, open_access.is_oa, author.id, institutions.id, cited_by_count, doi, has_abstract, and ~150 moreAuthors has_orcid, last_known_institutions.id, works_count, cited_by_count, orcidSources is_oa, is_in_doaj, type, country_code, host_organization, issnInstitutions country_code, type, is_global_south, continent, ror, has_rorTopics domain.id, field.id, subfield.id, works_countKeywords works_count, cited_by_countPublishers country_codes, hierarchy_level, ror, parent_publisherFunders country_code, is_global_south, continent, ror, awards_count
Looking for text search? Filters match exact values. For full-text search in titles, abstracts, and other fields, see Searching .
