---
title: "Upstream dataset revisions"
method: GET
path: "/api/v1/un-population/sources"
tags: ["Statistical Agencies"]
---

# Upstream dataset revisions

`GET /api/v1/un-population/sources`

31 upstream source revisions published by the UN DESA Population Division: current World Population Prospects 2024, current World Urbanization Prospects 2025, plus historical WPP revisions and related child / maternal mortality datasets. Each entry carries the recommended citation text.

## Response `200`

Upstream dataset revisions with recommended citations.

- EnvelopeUNPopSourcesPayload
  - `data` UNPopSourcesPayload, required
    - `sources` UNPopSource[], required — 31 upstream dataset revisions (WPP 2024, WUP 2025, historical WPP revisions, child and maternal mortality, etc).
      - `id` integer, required — UN DESA source id.
      - `name` string, required — Dataset name (e.g. World Population Prospects, World Urbanization Prospects).
      - `sourceYear` integer, nullable — Revision year (e.g. 2024 for WPP 2024, 2025 for WUP 2025).
      - `startYear` integer, nullable — First covered year in this revision.
      - `endYear` integer, nullable — Last covered year in this revision (projections included).
      - `citation` string, nullable — Recommended citation text published by UN DESA.
      - `url` string, nullable — Canonical URL for the upstream dataset.
      - `author` string, nullable — Publishing authority (United Nations Population Division).
    - `total` integer, required — Total number of source revisions returned.
  - `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.

---

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