What is a Hashi solver?
A Hashi solver is a tool that solves Hashiwokakero, also called Bridges, by applying the standard bridge puzzle rules. Each numbered island must receive exactly that many bridge lines, bridges can only run horizontally or vertically, and bridges cannot cross another route.
This online Hashi puzzle solver is made for custom grids. Add the islands from your puzzle, enter any bridges or no-bridge marks you already know, then use Solve for the completed network or Next move for a smaller hint.
- Solve a Hashi puzzle from a newspaper, book, app or printable sheet.
- Check whether your current bridge marks are still possible.
- Find a next logical move instead of guessing.
- Test a Hashiwokakero puzzle you are creating.
How to use this Hashi solver
Choose a grid size, select an island number, and click cells to place numbered islands. Use the clear option in the number picker to remove an island. When all islands are entered, switch to Bridges mode.
In Bridges mode, click a visible route between two islands to cycle through a single bridge, double bridge, no bridge and unknown. If you prefer, click one island and then another island in the same row or column.
- Create the grid size you need.
- Add every numbered island from the original puzzle.
- Mark any bridges or no-bridge deductions you already know.
- Press Next move for one forced step.
- Press Solve to fill the complete connected bridge network.
Hashi rules the solver checks
The core Hashi rules are simple but strict. An island numbered 4 could be connected by two double bridges, four single bridges, or another mix that reaches four total bridge lines. No pair of islands can have more than two bridges.
A finished Hashiwokakero solution must also be one connected group. That connected-network rule is what stops separate clusters of islands from looking locally correct while still being wrong globally.
- Every island total must match its number.
- Only one or two bridges can connect the same pair of islands.
- Bridges are straight horizontal or vertical lines.
- Bridge lines cannot cross islands or other bridges.
- All islands must belong to one connected network.
Next move logic for Hashiwokakero
The Next move button first looks for direct Hashi deductions. If an island has already reached its number, remaining routes from that island can be marked as no bridge. If every available route is needed, the solver can force single or double bridges.
When direct counting is not enough, the solver compares valid completions and returns a bridge value that is the same in every solution it can find. That makes the hint useful for stuck puzzles while still revealing only one move.
- Full islands force unused routes to no bridge.
- Limited remaining capacity can force one or two bridges.
- A bridge on one route blocks crossing routes.
- Shared solution evidence can identify a forced next move.
Hashi solver keywords and search intent
This page targets people searching for Hashi solver, Hashi puzzle solver, Hashiwokakero solver, Bridges puzzle solver and online Hashi solver. Those searches usually want an interactive grid editor, not only a rule explanation.
Supporting sections cover Hashi rules, Hashiwokakero strategy, next move hints, island numbers, single bridges, double bridges, bridge crossings and connected groups so the article answers the common questions around the solver.
A worked Hashi deduction
The fastest openings come from islands whose number leaves no choice. Count an island's directions — up, down, left, right — that actually reach another island. If its number equals twice that many directions, every route must be a double bridge: a 4 with two neighbours, a 6 with three, or an 8 in the middle with four all fill completely. Draw those doubles first; they are certain.
High numbers near edges and corners are forced too. A 3 in a corner has only two directions but needs three bridge ends, and since no pair can hold more than two bridges, it must send at least one bridge each way — so you can place a single bridge in both directions at once. Each bridge you draw lowers the count on both islands it touches, often turning a neighbour into the next forced island.
- Count only the directions that actually reach another island.
- Number = twice the directions means double every route (4 with 2, 6 with 3, 8 with 4).
- A corner 3 must send at least one bridge each way.
- No pair of islands ever holds more than two bridges.
- Each bridge lowers both islands' remaining count.
The no-crossing and connectivity rules in play
Two global rules do more solving than they first appear to. Bridges never cross, so the moment you draw one, every route that would have to pass through it is dead — cross those off to expose new forced bridges elsewhere. On a busy board, a single long bridge can quietly remove several options at once.
The connectivity rule is just as active. Because every island must end up in one network, you can never make a move that seals a small group of islands off from the rest with no way back in. If completing two islands' counts would lock them into their own closed loop while other islands remain, that completion is wrong. Watching for that keeps you from a position that looks locally perfect but can never join up.
- A drawn bridge kills every route that would cross it.
- Cross off blocked routes to reveal new forced bridges.
- All islands must finish in one connected network.
- Never seal a group of islands off from the rest.
- A locally complete cluster that cannot connect is a wrong turn.
Hashiwokakero, Bridges and Nikoli
Hashi is short for Hashiwokakero, Japanese for 'build bridges,' a puzzle from Nikoli — the publisher behind Sudoku, Nurikabe and Slitherlink. In English it is usually called Bridges, and you may also meet it as Ai-Ki-Ai or Chopsticks. The numbered circles are islands, and the lines between them are the bridges that give the puzzle its name.
Like other Nikoli classics, a proper Hashi is built to have a single solution reachable by logic alone. This solver follows the standard rules — match every island's number, at most two bridges per pair, no crossings, and one connected network — so it works on any Bridges puzzle whatever name it carries.