---
title: "Side-by-side comparison of countries for one variable-year"
method: GET
path: "/api/v1/research/pwt/compare"
tags: ["Research"]
---

# Side-by-side comparison of countries for one variable-year

`GET /api/v1/research/pwt/compare`

Returns a single-year cross-section of up to 10 countries for one Penn World Table variable. Pass a comma-separated list of ISO 3166-1 alpha-3 codes via `countries`. Results are sorted descending by value, with any countries missing from the requested year surfaced in `missing_countries`. Useful for quick scatter-plot data or benchmark tables (e.g. compare the G7 on `ctfp` or the BRICs on `rgdpo`). Published under CC BY 4.0 with attribution to Penn World Table (Feenstra, Inklaar & Timmer, University of Groningen).

## Query parameters

- `countries` string, required — Comma-separated ISO 3166-1 alpha-3 country codes (max 10). Case-insensitive; normalised to uppercase.
- `variable` string — Penn World Table variable to compare (e.g. `rgdpo`, `ctfp`, `hc`, `labsh`).
- `year` integer, required — Year the comparison applies to.
- `version` string, nullable — Release selector. `pwt1100` (default) or `pwt1001` (legacy).

## Response `200`

Ordered cross-section of requested countries for one variable-year plus missing-country list.

- EnvelopePwtComparePayload
  - `data` PwtComparePayload, required — Side-by-side comparison of up to 10 countries for one variable-year.
    - `version` string, required — Release identifier.
    - `variable` string, required — Variable used for comparison.
    - `year` integer, required — Year the comparison applies to.
    - `observations` PwtCompareRow[], required — One row per country with data, sorted descending by value (nulls last).
      - `countrycode` string, required — ISO 3166-1 alpha-3 code.
      - `country` string, required — Country name.
      - `value` number, nullable — Variable value for this country in the requested year.
    - `count` integer, required — Number of countries returned.
    - `requested_countries` string[], required — ISO3 codes from the request (uppercased).
    - `missing_countries` string[], required — Subset of requested codes with no observation for the requested year.
    - `attribution` string, required — CC BY 4.0 attribution.
  - `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.
- `422` — Validation Error
- `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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