Numberlink solver facts at a glance
The Numberlink solver connects up to 16 pairs of colored dots on grids from 5x5 to 15x15, with paths that never cross and, by default, fill every cell. A typical 15x15 puzzle solves in under 2 seconds; the search stops after 8 seconds and says so. It is free, needs no account and runs in your browser.
| Grid sizes | Any width and height from 5 to 15 cells, square or rectangular |
|---|---|
| Dots | Up to 16 color pairs, lettered A to P, placed by tapping |
| Path rule | Paths run up, down, left and right, never cross or branch, and each joins one pair |
| Fill every cell | On by default; turn it off for puzzles that allow empty cells |
| Speed | Usually under 2 seconds on 15x15; the search stops after 8 seconds |
| No solution | Reported only after the full search; a time-out is reported as a time-out |
| Price and setup | Free, no account, no download; a board link reopens the puzzle and its answer |
How to use the Numberlink solver
Set the grid size, tap each pair of dots onto the grid and press Solve: the paths appear over the grid, one color at a time. It works for printed Numberlink puzzles and for the dot-connecting levels in Flow Free-style phone games.
- Set the size. Pick the width and height of your grid, from 5 to 15 cells each.
- Place the dots. Tap a cell to drop a dot, then tap its partner; the next tap starts a new color. Tap a dot to remove it, or tap a color to pick it.
- Choose the rule. Leave Fill every cell on when the whole board must be covered, and turn it off when empty cells are allowed.
- Press Solve. The paths are drawn over the grid, shortest first. Next, Back and Play step through them one color at a time.
- Keep the answer. Copy all paths lists every path cell by cell, and Copy board link saves a link that reopens the puzzle with its answer.
How the solver works
The solver turns the puzzle into a yes-or-no logic problem and searches it with clause learning, the method SAT solvers use, so it either finds the paths or proves there are none. Each cell gets a color and each pair of neighboring cells is either linked or not: a dot has exactly one link, every other cell has two, and linked cells share a color. Forced moves follow at once, every dead end becomes a new rule so the search never repeats it, and walled-off dots or cells no color can reach are reported before the search starts. Closed loops that touch no dot are ruled out as they appear.
Frequently asked questions
Why does the solver say my puzzle has no solution?
It says so only after checking every possibility, so a dot is almost certainly in the wrong cell or has the wrong color. A puzzle from a game always has a solution. If your puzzle allows empty cells, turn off Fill every cell and solve again.
What if the search times out?
The search stops after 8 seconds and says it found no answer in time; it never calls the puzzle impossible unless it proved it. Puzzles from games normally solve in under 2 seconds, so a time-out usually means a misplaced dot.
Does it have to fill every cell?
Only if you want it to. Fill every cell is on by default, as in most phone versions. With it off, paths only need to join their pairs, and any path that runs alongside itself takes the shortcut.
What if a puzzle has more than one solution?
The solver shows one of them. Well-made puzzles have exactly one, so the answer matches the one in your game.
Does it work with bridges, warps or hexagon grids?
No. It solves the classic rule on a square or rectangular grid: paths turn only at cell centers, never share a cell and never jump to the other side of the board.
Is the Numberlink solver free?
Yes. It is free, with no account and no download, and it runs in your browser. A board link keeps the dots in the link itself.