DDI API

REST API for DDI (Data Documentation Initiative) metadata: study units, datasets, variables, concepts, schemes, and related resources.

Swagger UI

Interactive OpenAPI 3.1 documentation — browse every endpoint and try requests against the live mock.

The mock server is at ddi-api.making-sense.info (base path /ddi/v1). The contract itself lives in ddi-rest.yaml.

Quick start

# Catalog of all mock items
curl https://ddi-api.making-sense.info/ddi/v1/items

# Variables (DDI JSON is the default)
curl https://ddi-api.making-sense.info/ddi/v1/variables

# Same list as DDI XML
curl -H "Accept: application/vnd.ddi.structure+xml;version=3.3" \
  https://ddi-api.making-sense.info/ddi/v1/variables

More examples, filters, and identifier rules: Mock API endpoints.

Using the API

• Entry points: GET /items (full ItemCatalog) and GET /items/{itemIdentifier} (one object, any type). Use /variables, /concepts, etc. when you already know the type.
• Identifiers: a DDI URN (urn:ddi:{agency}:{id}:{version}) is enough. A plain ID needs agencyID and version on the same request (400 otherwise).
• Lists are always paginated (limit default 100, max 1000; offset default 0). Page metadata is in Content-Range and Link, not in the DDI body. GET /items and single-item GETs are not paginated.
• Media types: application/vnd.ddi.structure+json;version=3.3 (default) and application/vnd.ddi.structure+xml;version=3.3. Generic application/json or application/xml return 406.

Full rules are in the Swagger UI description and in ddi-rest.yaml.

Local development

yarn mock              # mock server → http://localhost:4010
yarn build:swagger && yarn preview:swagger   # local Swagger UI → http://localhost:8080

You can also paste ddi-rest.yaml into Swagger Editor. Node 24+ is required (engines.node).

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