Slitherlinkthe loop puzzle game, free online
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Tap or drag between dots to draw · right-click or the X tool marks “no line” · 0% drawn
What is Slitherlink
The loop game where every number counts
Slitherlink is a logic puzzle played on a grid of dots. Numbers in the cells say how many of their four sides belong to the answer. Join neighbouring dots into one single closed loop — no crossings, no branches, no loose ends — so that every number is exactly right. The rules fit in a sentence and a good puzzle can still take an hour, which is why it has been a staple of puzzle magazines for decades.
- Endless unique puzzles
- Every puzzle is generated in your browser from a random loop and checked by a solver so it has exactly one answer. Pick 5×5, 7×7, or 10×10 and get a new grid the moment you finish.
- Plays in your browser
- No download, no install, no plugins. slitherlink.app has a puzzle ready the moment the page loads, on desktop and mobile.
- Draw, mark, undo
- Drag to draw whole runs, use X marks for ruled-out gaps, undo and redo without limit, and run a mistake check when you are unsure.
- Progress saved locally
- Best time, solve rate, and streak for each grid size are stored on your device — never on a server.
How to play
How to play Slitherlink
Slitherlink is a game of deduction. Read the numbers, rule out impossible edges, and close one loop through the dots that satisfies every clue.
- 1
Read the grid
The board is a grid of dots with numbers from 0 to 3 in some of the cells. A number tells you how many of that cell’s four sides are part of the final loop. Cells with no number are unconstrained.
- 2
Draw lines between dots
Tap or click the gap between two neighbouring dots to draw a line, or drag across several gaps to draw a whole run in one stroke. Lines are only horizontal or vertical and always join two adjacent dots.
- 3
Mark what cannot be a line
Switch to the X tool (or right-click) to mark a gap as “no line here”. X marks are your notes: they stop you from drawing a line you already ruled out and make the next deduction easier to see.
- 4
Close one single loop
Every dot ends up with either zero or exactly two lines. The lines must join into one closed loop that never crosses itself or branches. When every number is satisfied and the loop is closed, the puzzle is solved.
Tips to solve faster
- Start with the 0s: put an X on all four sides. Then look at every 0’s neighbours — the shared side is already ruled out.
- A 3 next to a 0 needs its other three sides. A 3 in a grid corner always uses both of its outer sides.
- Two 3s side by side: draw the line between them, plus the outer side of each 3 on the far end. Together those three parallel lines are always part of the solution.
- Corner 1s are easy: both outer sides of a 1 in a grid corner are ruled out, so put X marks on them.
- Look at every dot: it ends with zero or two lines. If a dot already has two lines, X the rest. If it has one line and only one open gap left, that gap must be a line.
- Do not close a loop early. If two path ends could join into a small loop while other clues are still unmet, that join must be an X.
- Mark X liberally. Every X you place makes a neighbouring dot or number easier to finish, and undo is free if you were wrong.
- When stuck, think inside and outside: the loop splits the board into inside and outside cells, and two neighbouring cells are on the same side unless a line runs between them.
FAQ
Slitherlink, answered
Straight answers about the free Slitherlink loop puzzle you can play online in your browser.
What is Slitherlink?
Slitherlink is a logic puzzle played on a grid of dots. Some cells contain a number from 0 to 3, which says how many of that cell’s four sides are part of the answer. You join neighbouring dots with horizontal and vertical lines to make one single closed loop that never crosses or branches, so that every number is correct. It is also known as Fences, Loop the Loop, and Takegaki, and is often just called a loop puzzle.
How do you play Slitherlink?
Draw lines between neighbouring dots. Each number must have exactly that many lines around its cell, every dot must have either zero or two lines touching it, and all the lines together must form one closed loop with no crossings, branches, or separate loops. Use X marks to record gaps that cannot hold a line. When the loop closes and every clue is satisfied, the puzzle is solved.
Is Slitherlink free to play online here?
Yes. slitherlink.app is completely free and runs entirely in your browser. There is nothing to buy, download, or install, and there are no interruptive video ads, premium tiers, or paywalls. Open the page and a puzzle is already waiting.
Do I need to download an app or create an account?
No. The game is the website — a 100% browser-based build with no app store download and no sign-up. Your best times and streaks are saved locally in your browser, so there is no login to manage.
What do the numbers mean?
A number in a cell is the count of that cell’s four sides that are drawn as lines. A 0 means no sides are used, a 1 means exactly one side, a 2 means two, and a 3 means three. Cells without a number can have any number of lines around them. Once a number is fully satisfied it dims on the board, and if you draw too many it turns red.
Does every puzzle have exactly one solution?
Yes. Each puzzle is generated from a random closed loop, and clues are then removed one at a time. A removal is kept only when a solver confirms the puzzle still has one and only one solution. That means the answer never depends on a coin-flip, although larger 10×10 puzzles can need you to follow a path several steps ahead.
How do I get started on a puzzle?
Begin with the certain moves: X all four sides of every 0, draw the three sides around a 3 that touches a 0, and use both outer sides of a 3 in a corner. Then work dot by dot: a dot with two lines gets X marks on its remaining gaps, and a dot with one line and a single open gap must continue through it. See the tips page for the full pattern list.
Which grid size should I pick?
5×5 is a warm-up that usually takes a minute or two, 7×7 is the standard size and takes several minutes, and 10×10 is the challenge with long loops and sparse clues. Each size keeps its own best time and streak, so switching sizes never damages a record.
Does the game save my progress?
Your best time, solve rate, streaks, chosen grid size, and sound setting are saved locally in your browser. Nothing is sent to a server and there is no account. Because the save lives on the device, a different phone, a new browser profile, or cleared site data looks like a fresh start. A puzzle in progress is not saved if you close the tab.
Can I play Slitherlink on mobile?
Yes. The layout is built for touch: tap a gap between two dots to draw a line, drag to draw several at once, and use the Line / X button under the board to switch to X marks. The board and all controls fit on one portrait screen, and starting a new puzzle is instant with no page reload.