I wanted to build more than another Sudoku page
A few months ago, I started building SudokuFR, a free Sudoku platform for French-speaking players.
The original idea was simple: create a clean place where anyone could open a Sudoku grid and start playing without creating an account.
But the project quickly became much bigger.
Today, SudokuFR includes classic Sudoku, daily puzzles, multiple variants, solving tools, statistics, achievements, printable grids, and learning resources.
And I’m still building it.
What is SudokuFR?
SudokuFR is a free web-based Sudoku platform built primarily for French-speaking players.
You can play:
- Classic 9×9 Sudoku
- Easy, Medium, Difficult and Expert levels
- Daily Sudoku
- Killer Sudoku
- Sudoku X
- Irregular Sudoku
- 4×4 Sudoku
- 6×6 Sudoku
- 16×16 Sudoku
- Samurai Sudoku
There is no account required.
Open the site, choose a puzzle, and play.
Building the actual game experience
One thing I didn't want was a Sudoku site that simply displayed a grid.
I wanted the game itself to feel useful.
So the player can use features such as:
- Notes
- Candidates
- Hints
- Grid checking
- Undo and redo
- Checkpoints
- Timer
- Progress tracking
- Printing
- Sharing
The platform also keeps game statistics and achievements so players can see their progress over time.
Supporting different Sudoku variants was the interesting part
Classic 9×9 Sudoku was only the beginning.
Different variants require different grid rules and UI behavior.
For example, Sudoku X adds diagonal constraints, Killer Sudoku introduces cages, Irregular Sudoku replaces the traditional 3×3 boxes with irregular regions, and Samurai Sudoku combines five overlapping 9×9 grids.
I also added a playable 16×16 Sudoku using numbers and letters.
Building these variants forced me to think much more carefully about puzzle validation, interaction state, and reusable game logic.
Why I chose Next.js
SudokuFR is built with Next.js.
For this project I needed both:
- A highly interactive game experience.
- Pages that are fast, crawlable and useful outside the game itself.
SudokuFR isn't only an application.
It also contains guides about Sudoku rules, solving techniques, different Sudoku types, printable puzzles, and a Sudoku solver.
Using Next.js made it easier for me to combine these content pages with the interactive parts of the product in the same project.
SEO influenced the architecture too
Organic search is an important part of the project.
Instead of putting everything behind one JavaScript application route, different useful experiences have their own URLs.
For example:
/sudoku-killer//sudoku-x//sudoku-irregulier//sudoku-16x16//sudoku-samurai//solveur-sudoku//sudoku-a-imprimer//techniques-sudoku/
The goal is that each page should be useful to a human visitor even before thinking about rankings.
This also pushed me to work on internal linking, structured content, accessibility, performance and indexability while building the product.
Something I learned from this project
A seemingly simple product can become technically interesting very quickly.
A Sudoku grid looks simple.
But once you start adding:
- multiple puzzle types,
- persistent game state,
- hints,
- statistics,
- accessibility,
- mobile layouts,
- printable content,
- SEO pages,
- and different puzzle sizes,
the architecture starts to matter a lot.
It has been a good reminder for me that small products are often great places to learn.
Why I built it
This project wasn't created just because I found a keyword or wanted another website.
I genuinely like Sudoku and wanted to build something useful for people who enjoy it too.
My goal is to keep improving SudokuFR and gradually turn it into one of the most complete free Sudoku experiences for French-speaking players.
There is still a lot I want to add.
I'd love your feedback
If you enjoy Sudoku — or just like looking at side projects — I'd love to know what you think.
👉 SudokuFR: https://sudokufr.fr/
I'm especially interested in feedback about:
- the gameplay UX,
- the Sudoku variants,
- mobile usability,
- and features you think a modern Sudoku platform should have.
Thanks for reading 👋
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