Games and entertainment decision
Sudokuunlimited
A small, one-developer replacement is realistic: the core generator/solver exists as open source and the product is a single-site web app without durable moats, so building and hosting an equivalent is feasible within a week and modest monthly upkeep.
Visit website↗Built by Yuyu, who ships 11 products in this index
Not priced
No pricing page we fetched carried a figure, so there is nothing to compare against. The build side is still real.
$100one-off32 h to build
$0/mo3 h/mo upkeep
No published price to break even against.
Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need - the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship. All Sudokuunlimited alternatives, with the arithmetic →
What a replacement has to do
- Generate a valid Sudoku puzzle, render the 9x9 grid in-browser, accept and validate user input with pencil-marks and hints, run/offer a solver for the current puzzle, and serve a daily-challenge variant.
What it still won’t have
- Existing domain, branding, and any returning user base
- Built-in Daily Challenge history tied to Sudoku Unlimited site
- The site’s exact UI polish, content copy, and any undisclosed features
What remains hard
- Product polish and ongoing maintenance
First-year cost
No published price
Sudokuunlimited does not publish a price we could read, so there is nothing to compare against. What building costs is below.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a single-developer self-hosted Sudoku web app using Node.js + Express for a small backend, PostgreSQL (or SQLite) for storing the daily challenge and completions, and a React frontend. Core features in scope: (1) integrate an open-source JS Sudoku generator/solver (robatron/sudoku.js) to produce puzzles at multiple difficulty levels and an API endpoint to request a puzzle, (2) React UI to render a 9x9 grid with keyboard/touch input, pencil-marks, undo, hints, and a solver button, (3) backend scheduled job to publish one Daily Challenge puzzle per day and an endpoint to retrieve it, (4) simple user session handling (no auth required) to track local progress, (5) privacy-friendly analytics integration (no personal data). Out of scope: user accounts/leaderboards, OCR input, and mobile native apps. Include error handling for generator/DB failures, validation for puzzle uniqueness, and automated tests for generator integration, solver correctness, and API endpoints. Provide a Dockerfile and deployment instructions for a small VPS (1 CPU, 1GB RAM).
How we checked
How the score was reached
- Build verdict base78
- An open-source build was found+5
- 2 cited sources+1
- 3/3 assessment runs agreed+4
- Evidence score88
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time - so the same evidence always produces the same number.
How scoring works →Cited sources · 2
Every page the run actually retrieved.
- official productSudoku Unlimited — official product
- open sourcerobatron/sudoku.js
Integrity checks
What held up, and what did not.
