DCAT -- Data Catalog Vocabulary

DCAT is a W3C Recommendation (latest version: DCAT 3, published 2024) for describing datasets and data services in a catalog. It enables interoperability between data catalogs by providing a common RDF vocabulary. DCAT is the metadata standard behind data.gov, data.europa.eu, and many national open data portals.

Standard Overview

Full Name:Data Catalog Vocabulary

Maintained By:W3C Dataset Exchange Working Group

Current Version:DCAT 3 (W3C Recommendation, 2024)

Namespace:http://www.w3.org/ns/dcat#

Serialization:RDF/XML, Turtle, JSON-LD, N-Triples

Specification:w3.org/TR/vocab-dcat-3

DCAT Classes

Class	Description	Required Properties	Key Optional Properties
dcat:Catalog	A curated collection of metadata about resources (datasets and data services).	`dct:titledct:descriptiondcat:dataset`	`dct:publisherdct:languagedcat:themeTaxonomydct:issued`+4 more
dcat:Dataset	A collection of data, published or curated by a single agent, and available for access or download.	`dct:titledct:description`	`dcat:distributiondcat:keyworddct:publisherdcat:theme`+7 more
dcat:Distribution	A specific representation of a dataset, such as a downloadable file or an API endpoint.	`dcat:accessURL`	`dcat:downloadURLdct:titledct:descriptiondct:format`+6 more
dcat:DataService	A collection of operations that provides access to one or more datasets or data processing functions.	`dct:titledcat:endpointURL`	`dcat:endpointDescriptiondcat:servesDatasetdct:descriptiondct:publisher`+1 more
dcat:Resource	Abstract base class for catalog entries. Not used directly; serves as parent class for Dataset, DataService, and Catalog.	Abstract class	`dct:titledct:descriptiondct:identifierdct:issued`+4 more

DCAT-AP (Application Profile for European Data Portals)

DCAT-AP is the European application profile of DCAT, maintained by the European Commission. It constrains DCAT for use within European data portals by specifying mandatory, recommended, and optional classes and properties, ensuring interoperability across EU member state portals.

Current Version:DCAT-AP 3.0 (2024)

Adopted By:data.europa.eu, all EU member state portals

Key Addition:Controlled vocabularies for theme, license, format, frequency

Validation:SHACL shapes for automated metadata validation

JSON-LD Example

A DCAT Dataset description serialized as JSON-LD, describing a monthly employment statistics dataset with a CSV distribution:

{
  "@context": {
    "dcat": "http://www.w3.org/ns/dcat#",
    "dct": "http://purl.org/dc/terms/",
    "foaf": "http://xmlns.com/foaf/0.1/"
  },
  "@type": "dcat:Dataset",
  "dct:title": "Monthly Employment Statistics",
  "dct:description": "Monthly employment, unemployment, and labor force data by state and metropolitan area.",
  "dct:publisher": {
    "@type": "foaf:Organization",
    "foaf:name": "Bureau of Labor Statistics"
  },
  "dcat:keyword": ["employment", "unemployment", "labor force"],
  "dct:issued": "2020-01-01",
  "dct:modified": "2026-03-01",
  "dct:accrualPeriodicity": "monthly",
  "dcat:distribution": {
    "@type": "dcat:Distribution",
    "dcat:downloadURL": "https://download.bls.gov/pub/time.series/la/",
    "dct:format": "text/csv",
    "dct:title": "CSV Download"
  }
}

Key Relationships

dcat:Catalog contains one or more dcat:Dataset (via dcat:dataset)

dcat:Dataset has one or more dcat:Distribution (via dcat:distribution)

dcat:Catalog may reference dcat:DataService (via dcat:service)

dcat:DataService serves one or more dcat:Dataset (via dcat:servesDataset)