Free online Akari puzzle solver. Learn solving techniques and master Light Up puzzles.
MeowTrail offers a built-in Akari solver that helps you check your work or get past tricky spots in any Light Up puzzle. Here is how to make the most of it:
Unlike standalone Akari solver tools that require you to manually input a grid, MeowTrail's solver is integrated directly into the gameplay experience. You solve the puzzle yourself while the tool catches mistakes and offers guidance along the way.
Every Akari solver — whether it runs in your browser or on a server — relies on two core algorithms: constraint propagation and backtracking.
Constraint propagation is the first pass. The solver examines each numbered wall cell and each empty cell to deduce which placements are forced. For example, if a wall cell marked "4" has exactly four open neighbors, all four must contain light bulbs. If a wall cell marked "0" has open neighbors, none of them can hold a bulb. The solver repeats this deduction loop until no more cells can be resolved by logic alone.
Backtracking kicks in when logic stalls. The solver picks an undecided cell, tries placing a bulb there, and propagates the consequences. If a contradiction appears (two bulbs see each other, or a wall count is violated), the solver backtracks and tries the opposite choice. This search tree explores all possibilities efficiently, pruning branches as soon as conflicts arise.
Together, these two techniques guarantee that a well-implemented Akari solver finds the unique solution to any valid puzzle — usually in milliseconds, even for large grids. The same principles power solvers for Sudoku, Nonograms, and other logic puzzles.
Reaching for an Akari solver is not cheating — it depends on how you use it. Here are two common scenarios:
If you are new to Light Up puzzles, a solver can teach you the logic patterns faster than trial and error. Place a few bulbs, check the solver's feedback, and study why certain cells are forced. Over time you will internalize the techniques and need the solver less. Think of it as training wheels that help you build intuition.
Even experienced players hit walls on hard puzzles. When you have stared at a grid for ten minutes and cannot find the next move, a single hint from the solver can break the logjam. You keep your momentum and still solve most of the puzzle yourself. This is far more satisfying than abandoning the puzzle entirely.
The key is to use the Akari solver as a learning partner, not a replacement for your own thinking. Peek at hints sparingly, study the reasoning, and you will improve rapidly.
Master these four techniques and you will solve most Akari puzzles without any help from a solver tool.
A wall cell numbered "4" must have light bulbs in all four adjacent cells. A wall cell numbered "0" forbids bulbs in every adjacent cell. Start every puzzle by scanning for 0s and 4s — they resolve the most cells immediately.
Cells in corners or along edges have fewer neighbors, which makes them easier to reason about. A corner cell has only two adjacent cells, so if one is blocked by a wall, the other must hold a bulb if the corner cell needs to be lit. Edge cells follow the same principle with three neighbors instead of four.
Every light bulb shines in a straight line along its row and column until it hits a wall. If placing a bulb in a candidate cell would shine on another bulb, that placement is illegal. Use this to eliminate candidates: trace the rays from existing bulbs and mark every cell they illuminate as "cannot hold a bulb."
If a white cell can only be lit by one specific neighbor (because walls block all other directions), that neighbor must contain a bulb. This technique is especially powerful in narrow corridors between walls where the lighting options are severely limited.
Yes. MeowTrail is completely free — no account, no subscription, no ads. Every puzzle comes with built-in validation and hint features that function as a light up puzzle solver. Just visit the site and start playing.
MeowTrail's built-in solver works only with MeowTrail puzzles. If you have an Akari grid from a newspaper or another app, you can use a standalone Akari solver tool that accepts custom grid input. However, we recommend trying MeowTrail's own puzzles first — they are designed to teach you progressively harder techniques.
They are the same puzzle. "Akari" (明かり) is the Japanese name meaning "light," while "Light Up" is the English translation used by Nikoli, the publisher that popularized the puzzle. Both names refer to the grid-based logic game where you place light bulbs to illuminate every white cell while respecting numbered wall constraints. MeowTrail uses both terms interchangeably.
