Sudoku infrastructure

Sudoku puzzles, engineered for production.

A pre-generated pool of solvable, uniquely-difficult Sudoku puzzles — served over a fast edge API, exported in bulk for print, or wired straight into an AI pipeline with MCP. Built to remove one problem from your stack, not add one.

Read the API docs See a live puzzle

Guaranteed unique solution
Near-duplicate filtering
Calibrated difficulty, Easy → Expert

GET /api/v2/puzzles/random

curl "https://sudoku-gen.gridhearth.com\
  /api/v2/puzzles/random?difficulty=medium"

{
  "puzzle_id": "p_7d2a1c44",
  "puzzle": "530070000600195000098...079",
  "difficulty": "medium",
  "difficulty_level": 3,
  "clue_count": 30,
  "symmetric": true,
  "hardest_technique": "hidden_pair",
  "techniques": ["naked_single", "hidden_single", "hidden_pair"],
  "score": 812, "stars": 4
}

The solution lives behind its own endpoint — never in this response.

5difficulty tiers, calibrated

3ways in — API, bulk export, MCP

0near-duplicates in the pool

24/7served from the edge

Built for

Puzzle infrastructure for teams shipping content, not players looking to compete.

Three ways to pull from the same quality-gated puzzle pool, depending on where in your stack you need it.

Websites & apps

Pull ready-to-play puzzles on demand over a REST API — a guaranteed unique solution, calibrated difficulty, and image export, without running a generator of your own.

Read the API docs

Publishers & print

Generate thousands of unique, quality-gated puzzles offline and export straight into book-ready PDFs — no near-duplicates slipping into the same volume.

Download the generator

AI & content pipelines

An MCP server exposes generate, solve, rate and explain as tools an agent can call directly — no bespoke API wrapper to write and maintain.

See the MCP docs

How it works

Puzzles are generated once, quality-gated hard, and served many times.

Generation is CPU-heavy, so it happens in batches ahead of time — not on every request.

Generate

The Python engine produces puzzles in bulk, then runs a dedup + near-duplicate + QA gate before anything is kept — the problem that started this whole project.

Pool

Passing batches sync to Cloudflare D1, R2 and KV — metadata, files and a fast cache, ready to serve globally from the edge.

Serve

Pulled over the API, exported in bulk for a print run, or called through MCP by an agent — whichever fits your stack.

Why this exists

“GridHearth publishes free Sudoku online and paperback puzzle books on Amazon. We needed a way to produce genuinely unique puzzles at volume — not just re-shuffled duplicates — for our own AI-managed web content and book pipeline. This is the infrastructure we built to solve that. It runs our own books and web content today; we’re opening it up for other teams solving the same problem.”

— Built and operated by GridHearth

Ready to look at the docs?

Authentication, rate limits, every endpoint, and copy-pasteable examples in curl, Python and TypeScript.

Read the API docs Download the desktop app