DCAT-AP-ES: How to Publish Your Data Catalogue as Open Data in Spain

Any city council, provincial council, or regional department that manages open data has run into the same question sooner or later: how do I make my data catalogue visible and reusable beyond my own portal? Publishing a dataset on a municipal website is fine, but if that data doesn't speak the same language as the rest of the administrations, it stays isolated. That's where DCAT-AP-ES comes in: the metadata profile that allows a Spanish data catalogue to be understood, indexed, and reused by national and European-level portals.

The problem isn't a lack of data, but a lack of a common language to describe it. Each organization tends to structure its metadata its own way: some indicate the license, others don't; some version their datasets, others replace them without leaving a trace. When datos.gob.es or data.europa.eu try to harvest this information automatically, they need a standard that guarantees that "title," "publisher," or "last update date" always mean the same thing, regardless of where you look.

In this article, we explain what DCAT-AP-ES is, why it's the mandatory gateway for any administration that wants its open data to have real reach, and how a modern data space can automate much of that technical work.

What DCAT-AP-ES Is and Where It Comes From

DCAT-AP-ES is the Spanish adaptation of the European DCAT-AP profile (Data Catalogue Vocabulary Application Profile), which is itself based on the W3C's DCAT vocabulary. In simple terms, it's a set of rules that defines which fields a dataset record must have and how they should be filled in so that any automated system can read them unambiguously.

A data catalogue published according to DCAT-AP-ES describes, among other elements:

• The dataset: title, description, subject matter, geographic and temporal coverage.
• The distribution: the specific file or service (CSV, API, JSON), its format, and its access URL.
• The publisher: which public body is responsible for that data.
• The license: the conditions under which the information can be reused.
• The update frequency and the publication and modification dates.

This standardization is what allows a regional transparency portal, a provincial one, and datos.gob.es to exchange records automatically through harvesting, without a technician having to manually upload each record.

Why It Matters for a Local or Regional Administration

For a provincial council, a mid-sized city council, or a regional department, complying with DCAT-AP-ES isn't a technical whim — it's what determines whether their open data is visible outside their own website.

Imagine the case of a city council in Castile and León that publishes its business registry, annual budgets, and water consumption data on its municipal portal. If those datasets aren't described with DCAT-AP-ES metadata, datos.gob.es can't index them correctly, and a citizen, a business, or a researcher searching for "municipal budgets Castile and León" will never find them through the national portal.

With correct metadata, however, that same dataset automatically appears in datos.gob.es searches and, potentially, in data.europa.eu, the European open data portal. This expands the real audience for public information without the administration having to do active outreach: the standard does the work of connecting catalogues.

Complying with the profile also avoids duplication and misinterpretation. When several organizations use the same structure, it becomes much easier to compare and combine data from different sources — something especially useful for transparency, public procurement, or environmental management.

From Metadata to Real Interoperability

DCAT-AP-ES isn't just a matter of visibility — it's the technical foundation of interoperability between catalogues. When metadata follows the same schema, a system can:

• Automatically detect whether a dataset already exists in another catalogue or is an outdated copy.
• Compare the declared update frequency against the actual one.
• Link related datasets from different organizations using common identifiers.
• Generate aggregated catalogues (for example, a regional one that gathers data from all the municipalities in a province) without rewriting metadata by hand.

This interoperability is also what allows open data to coexist with more demanding governance schemes, such as those used in a data space, where it matters not only that the metadata is readable, but that its origin and the conditions under which it can be used can be verified.

Technical Steps to Publish a DCAT-AP-ES–Compatible Catalogue

Adapting an existing data catalogue to DCAT-AP-ES tends to follow a similar path, regardless of the size of the organization:

1. Audit the current catalogue. Review which datasets exist, what metadata they already have, and what's missing (license, publisher, temporal coverage, etc.).
2. Map internal fields to the DCAT-AP-ES vocabulary. Translate the internal structure (for example, a spreadsheet with its own column names) into the profile's standard properties.
3. Choose the serialization format. DCAT-AP-ES is usually expressed in RDF, though XML or JSON-LD representations are also accepted depending on the receiving system.
4. Generate the catalogue file or expose an endpoint. The catalogue can be published as a downloadable file or, more robustly, as a service that can be queried and harvested automatically.
5. Validate against the official profile. Check that the required fields are present and well-formed before announcing the catalogue to datos.gob.es.
6. Register the catalogue for periodic harvesting. From this point on, any update to the source catalogue is automatically reflected in the portals that harvest it.

Done manually, this process can take weeks in organizations with hundreds of datasets and small technical teams — which is precisely the typical profile of many city and provincial councils in Castile and León.

How a Data Space Simplifies DCAT-AP-ES Publication

This is where a data space brings an efficiency leap. A modern data space includes a federated catalogue designed to natively export to DCAT-AP-ES. In practice, this means an entity — whether a public utility company or a provincial administration — can register its datasets once in the data space's admin interface, describing title, license, format, and frequency through a no-code panel. The system itself takes care of translating that information into the DCAT-AP-ES vocabulary and exposing it in a format ready to be harvested by datos.gob.es or data.europa.eu.

This solves two problems at once. On one hand, it avoids the manual work of mapping and validating against the profile, which is usually the slowest part of the process. On the other, it keeps the internal data governance catalogue and the public open data catalogue in sync, so that any change in access conditions or dataset updates is automatically reflected in both places, without depending on someone remembering to update two separate systems.

Open Data and Sovereign Data: Two Sides of the Same Strategy

It's worth clearing up a common confusion: publishing open data according to DCAT-AP-ES doesn't compete with data sovereignty — it complements it. A data space allows both types of datasets to be managed in the same environment: those that are freely opened for any reuse, and those that are only shared under specific conditions with authorized partners, applying differentiated access policies for each case.

This is especially relevant for administrations that combine transparency obligations with sensitive data: a provincial council can publish its management indicators openly while, at the same time, sharing critical infrastructure data in a controlled way only with certain organizations — using the same federated catalogue as a starting point and deciding the level of openness on a case-by-case basis.

Ultimately, DCAT-AP-ES solves the problem of describing data, while the access policy layer solves the problem of who can use it and how. A well-designed data space allows both layers to be managed without duplicating effort or systems.

Take the Next Step With Your Data Catalogue

If your administration wants its open data to be genuinely visible and reusable, adapting it to DCAT-AP-ES is an unavoidable step — and it doesn't have to be a long or costly project. A modern data space offers a federated catalogue ready to export metadata compatible with datos.gob.es and data.europa.eu through a simple interface, with no need for advanced technical knowledge.

If you want to learn how to apply this to your organization or resolve specific questions about your current catalogue, look for a technology partner with experience in data spaces who can guide you through the process.