Instant to start
Open the page and a puzzle is already on the board. No account wall, no download, no splash video — you can place your first digit before you finish reading this sentence.
About Us
About futoshiki.app
We publish a free, modern browser version of Futoshiki — the Japanese inequality logic puzzle — with 4×4 to 9×9 boards, pencil notes, unlimited undo, hints, and a layout that works on any screen.
Our craft
Every sign is a clue.
Read the givens, follow the signs, cross out candidates until one digit remains. That loop is everything we design around.
- Board sizes, 4×4 to 9×9
- 6
- Solution per puzzle
- 1
- Undo & new puzzles
- ∞
Board sizes, 4×4 to 9×9
Solution per puzzle
Undo & new puzzles
What we make
A free Futoshiki that stays in the browser
futoshiki.app is the site behind our version of Futoshiki. The product is a single-player logic puzzle: fill an N×N grid with the digits 1 to N so that no digit repeats in a row or column and every inequality sign between neighbouring cells is true.
We are not an app-store publisher and there is nothing to download. The game is the website. That keeps load times short, works on phones and desktops alike, and avoids an account wall. Your unfinished puzzle, best times and streaks live in local browser storage on your device.
If you are comparing this to another Futoshiki site, this page only speaks for futoshiki.app. The rules, controls, and board sizes described in our how-to-play guide and FAQ match this exact build.
Our story
From Japanese newspapers to your browser tab
Futoshiki is a young puzzle by newspaper standards but it has travelled far. We treat that as a responsibility to get the rules exactly right and the friction as close to zero as we can.
- 01
A Japanese name
Futoshiki is the Japanese word for "inequality" (不等式). The puzzle is generally credited to Tamaki Seto, who published it in Japan in 2001. It belongs to the Latin-square family — each digit once per row and column — with inequality signs supplying the clues instead of Sudoku-style boxes.
- 02
Around the world
From Japan the puzzle spread through newspapers and puzzle websites, where it is also sometimes called "Unequal". Sizes usually run from 4×4 up to 9×9, and most publishers grade puzzles by how many clues they leave and how much chained reasoning they demand.
- 03
This build
futoshiki.app is an independent, modern implementation. Puzzles are generated in your browser from a random Latin square, then stripped of clues while a solver confirms the answer stays unique. What is new is a board that fits a phone screen, pencil notes that prune themselves, live rule checking, and no account or ads.
What we stand for
Principles behind every puzzle
Honest puzzles
Every puzzle is checked by a solver and has exactly one solution reachable by logic. Nothing is gated behind a "pro" toggle and hints are yours to use whenever you like.
Yours to keep
Your unfinished puzzle, best times and streaks per board size and difficulty live on your device. We do not hold your record hostage behind a login, because there is no login.
Free, for real
The whole game is free. No energy meters, no interstitial video ads between puzzles, no surprise paywall on the hint button.
Who it is for
Players who want a clean logic puzzle
futoshiki.app is a family-friendly, single-player game with no chat and no store. A poor fit if you want multiplayer or live events; a good fit if you want the real Futoshiki, with proper unique-solution puzzles, on whatever screen is nearby.
Short sessions
A 5×5 takes a few minutes and a 9×9 takes a good while. Pick the size that fits the gap you have — a phone on the couch or a browser tab between tasks.
Logic, not reflexes
There is no clock forcing a move and nothing to react to. The whole challenge is spotting the next deduction, which makes it a good fit for Sudoku and Kakuro players.
Play without an account
Your record stays on the device you played on. That is a deliberate trade: instant play and real privacy, with no cloud restore.
Why this site
How futoshiki.app is different
Futoshiki puzzles are available in many places. This one exists to ship a single honest, fast version — correct rules, generated puzzles with guaranteed unique solutions, and no clutter.
Generated and verified in the browser
A seeded generator builds a random Latin square, then removes clues in random order and keeps each removal only if a backtracking solver still finds exactly one solution. Easy stops early; Hard strips as far as the solver can prove.
Tools that respect your time
Notes that update themselves when you place a digit, unlimited undo, live red highlights for duplicates and broken signs, and a hint that fills a correct cell when you are stuck.
No clutter
No auto-playing video, no fake "download our app" banners, no dark patterns around the settings. The how-to-play guide and FAQ describe this exact engine, not a generic write-up.
How we build
Designed for the browser you already have
The game runs entirely on the web: fast loads, tap and keyboard controls, and progress that stays local unless you clear your browser data. We use lightweight analytics to see what helps players — never to gate the game behind a profile. The engine on the home page is the one described on our rules pages, so search results and the live game never drift apart.
Play anywhere
Phone, tablet, and desktop share one board. Tap a cell and a digit, or use the arrow keys, number keys and the shortcuts for notes, hint, undo, new puzzle and mute.
Progress on your device
Your unfinished puzzle, best time and streak per board size and difficulty are stored locally. You own the continuity of your record without signing up.
Quiet improvement
We watch aggregate usage through Google Analytics to improve pacing and polish. Details are in our Privacy Policy — never as a sales pitch.
Contact
Stay in the loop
Feedback on a puzzle, a bug report, partnership ideas, or a simple hello — we read every message. Hit the button and we will get back to you.
Stay in TouchPrefer the fine print first? Our legal pages cover how the site works and how we handle analytics.