Instant to start
Open the page and a puzzle is already on the board. No account wall, no download, no splash video — you can draw your first line before you finish reading this sentence.
About Us
About slitherlink.app
We publish a free, modern browser version of Slitherlink — the classic loop puzzle — with endless unique-solution grids, drag drawing, unlimited undo, a mistake check, and a layout that works on any screen.
Our craft
One loop. Every number.
Read the clues, rule out the impossible, close the loop. That chain of deductions is everything we design around.
- Grid sizes
- 3
- Solution per puzzle
- 1
- Fresh puzzles
- ∞
Grid sizes
Solution per puzzle
Fresh puzzles
What we make
A free Slitherlink that stays in the browser
slitherlink.app is the site behind our version of Slitherlink. The product is a single-player logic puzzle: read the numbers in a grid of dots and draw one closed loop, with no crossings or branches, so that every number matches the lines around its cell.
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. Best times, solve rates, and streaks live in local browser storage on your device.
If you are comparing this to another Slitherlink site, this page only speaks for slitherlink.app, which is independent and not affiliated with any other puzzle publisher. The rules, sizes, and controls described in our how-to-play guide and FAQ match this exact build.
Our story
From pencil magazines to your browser tab
Slitherlink has a long pedigree as a pencil-and-paper puzzle. We treat that as a responsibility to get the rules exactly right and the friction as close to zero as we can.
- 01
Loops on paper
Slitherlink belongs to a family of pencil puzzles where you draw a single closed line through a grid. It was popularised by the Japanese publisher Nikoli, which ran it in its puzzle magazines from the late 1980s, and it is known in English by several names: Slitherlink, Fences, Loop the Loop, and Dotty Dilemma.
- 02
Why it lasts
The rules fit in one sentence, yet solving requires real logic: local patterns around 0s and 3s, the two-lines-or-none rule at every dot, and long-range reasoning about which cells are inside the loop. There is no arithmetic and no guessing — the puzzle is a pure exercise in deduction.
- 03
This build
slitherlink.app is an independent, modern implementation of the same ruleset. The new part is the rendering and the tooling: a board that scales to any screen, drag-to-draw with an X tool, unlimited undo and redo, a mistake check, synthesized sound with a real mute, and a generator that creates a fresh unique-solution puzzle on demand.
What we stand for
Principles behind every puzzle
Honest puzzles
Every grid has exactly one solution, verified by a solver before you see it. Nothing is gated behind a "pro" toggle and nothing nags you to install an app.
Yours to keep
Best time, solve rate, and streak per grid size 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 forever. No energy meters, no interstitial video ads between puzzles, no surprise paywall on the mistake check.
Who it is for
Players who want a clean logic puzzle
slitherlink.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 Slitherlink, exactly as the magazines print it, on whatever screen is nearby.
Short sessions
A 5×5 takes a minute or two and a 7×7 a few minutes. Slitherlink is built for 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 entire challenge is deducing which edges must be lines and which cannot be.
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 slitherlink.app is different
Slitherlink has a handful of long-standing sites online. This one exists to ship a single honest, fast version — correct rules, endless verified puzzles, and no clutter.
Generated and verified
Each puzzle starts as a random closed loop. The clues are written from it, then removed one at a time; a removal is kept only when a solver confirms the puzzle still has a single solution.
Tools that respect your time
Drag to draw runs, an X tool for ruled-out gaps, unlimited undo and redo, and a check that flags wrong lines when you want it. A new puzzle is one tap away.
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, drag / tap / 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. Drag with a mouse, tap on a touchscreen, or use the keyboard shortcuts for undo, redo, check, tool, and new puzzle.
Progress on your device
Best time, solve rate, and streak per grid size 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.