API & MCP

Everything a person can do on Cartograph True Size of Countries (Mercator comparer), a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://cartographtruesize.usefulweb.app/api/v1/calculate – run Cartograph True Size of Countries (Mercator comparer)
GET https://cartographtruesize.usefulweb.app/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Cartograph True Size of Countries (Mercator comparer)

Moves a country outline (Natural Earth admin-0) to any place on the globe while keeping its true shape and area, and shows how big it looks on a Web-Mercator map at home and at the new place, next to its real geodesic area and an optional second country. It is the true-size engine of the Cartograph app.

Inputs of Cartograph True Size of Countries (Mercator comparer)
Field	Type	Default	Description
`country`	text	"GRL"	Country (English name or ISO code)
`target`	text	"2, 20"	Move it to. Coordinate of the new centre (anchor = centre of the bounding box of the largest part).
`rotationDeg`	number	0	Rotation (clockwise)
`compare`	text	—	Compare with (optional). A second country drawn at home and compared by true area.

Example request

Greenland moved to the equator, compared with DR Congo

curl -X POST https://cartographtruesize.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"country":"GRL","target":"2, 20","compare":"COD"}'

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

Streamable HTTP endpoint: https://cartographtruesize.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: cartograph_true_size
Local stdio connector: node src/mcp-stdio.ts --tool=cartograph-true-size

{
  "mcpServers": {
    "cartograph-true-size": { "type": "http", "url": "https://cartographtruesize.usefulweb.app/mcp" }
  }
}