API & MCP

Everything a person can do on Sudoku Maker (4×4 to 16×16, with Answer Key), a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://printshopsudoku.usefulweb.app/api/v1/calculate – run Sudoku Maker (4×4 to 16×16, with Answer Key)
GET https://printshopsudoku.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.

Sudoku Maker (4×4 to 16×16, with Answer Key)

Make printable sudokus from 4 × 4 for young children to 16 × 16 for experts. Every puzzle is proven to have exactly one solution, its difficulty is graded by the techniques a person needs (singles, locked candidates, pairs, triples, X-wing), and answer-key pages follow. Up to six per page, as a true-size PDF.

Inputs of Sudoku Maker (4×4 to 16×16, with Answer Key)
Field	Type	Default	Description
`size`	select (4, 6, 8, 9, 12, 16)	"9"	Grid size
`difficulty`	select (easy, medium, hard, expert)	"medium"	Difficulty
`count`	integer	4	Number of sudokus
`perPage`	select (1, 2, 4, 6)	"4"	Sudokus per page
`symmetric`	boolean	true	Symmetric clues (180° rotation)
`seed`	text	"sudoku-1"	Seed. The same seed and settings always give the same puzzles. Change it for new ones.
`title`	text	—	Title on the page (optional)
`answers`	boolean	true	Answer-key pages
`header`	boolean	true	Name and date line
`paper`	select (a3, a4, a5, a6, b5, letter, legal, tabloid, halfletter)	"a4"	Paper size
`orientation`	select (portrait, landscape)	"portrait"	Orientation

Example request

Four medium 9 × 9 sudokus on one page

curl -X POST https://printshopsudoku.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"size":"9","difficulty":"medium","count":4,"perPage":"4","seed":"sudoku-1"}'

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://printshopsudoku.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: printshop_sudoku
Local stdio connector: node src/mcp-stdio.ts --tool=printshop-sudoku

{
  "mcpServers": {
    "printshop-sudoku": { "type": "http", "url": "https://printshopsudoku.usefulweb.app/mcp" }
  }
}