---
title: "Maddison Project Database catalog - countries, regions, release metadata"
method: GET
path: "/api/v1/research/maddison/catalog"
tags: ["Research"]
---

# Maddison Project Database catalog - countries, regions, release metadata

`GET /api/v1/research/maddison/catalog`

Discovery endpoint for the Maddison Project Database (MPD2023). Returns publication metadata (release version, DOI, DataverseNL URL, publication date), the 169 countries in the workbook with their ISO 3166-1 alpha-3 codes and per-country first/last year of observation, the 8 analytical regions used by the Maddison Project with their stable slugs, the two variables (`gdppc`, `pop`), and the overall year range (1 AD through 2022). Use this before calling `/country/{iso3}`, `/regional`, or `/top` to confirm ISO3 codes and available year ranges. Published by Bolt and van Zanden at the University of Groningen under CC BY 4.0; full citation in every response envelope.

## Response `200`

Catalog listing with release metadata, country coverage, region list, and variable dictionary.

- EnvelopeMaddisonCatalogPayload
  - `data` MaddisonCatalogPayload, required — Catalog listing for the Maddison Project Database.
    - `release` MaddisonRelease, required — Release metadata for the loaded Maddison Project Database workbook.
      - `version` string, required — Release version identifier as published by the Maddison Project.
      - `doi` string, required — Digital Object Identifier for the DataverseNL dataset.
      - `published` string, required — Upstream publication date on DataverseNL (ISO 8601 UTC).
      - `url` string, required — DataverseNL landing page for the dataset.
      - `file` string, required — Source filename within the DataverseNL dataset.
    - `countries` MaddisonCatalogCountry[], required — Per-country coverage summary for all 169 ISO 3166-1 alpha-3 countries in the dataset.
      - `iso3` string, required — ISO 3166-1 alpha-3 country code used as the primary identifier.
      - `country` string, nullable — English country name as published in the workbook.
      - `region` string, nullable — Analytical region to which the country belongs.
      - `region_slug` string, nullable — Stable slug corresponding to `region`.
      - `first_year` integer, nullable — Earliest year for which this country carries at least one Maddison observation.
      - `last_year` integer, nullable — Latest year for which this country carries at least one Maddison observation.
    - `country_count` integer, required — Number of countries in the dataset.
    - `regions` MaddisonRegionRef[], required — The 8 analytical regions used by the Maddison Project.
      - `slug` string, required — Stable slug accepted by `/regional?region=` (e.g. `western-europe`, `east-asia`).
      - `name` string, required — Region label as spelled in the upstream workbook.
    - `region_count` integer, required — Number of regions (always 8 in MPD2023).
    - `variables` MaddisonVariableRef[], required — Variables carried by the Full data sheet.
      - `id` string, required — Stable variable identifier accepted by `/top?variable=`.
      - `label` string, nullable — Human-readable label for the variable.
      - `unit` string, required — Unit of measure.
      - `description` string, nullable — Methodology and interpretation notes for the variable.
    - `year_range` MaddisonYearRange, required — Year range present in the dataset.
      - `min` integer, nullable — Earliest year present in the workbook.
      - `max` integer, nullable — Latest year present in the workbook.
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

[API](https://skmtc.net/sugra/apis/sugra-api.md) · [All operations](https://skmtc.net/sugra/apis/sugra-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/sugra/sugra-api/versions/4c4530760ba1/schema)