{"v":1,"api":"ARLing static puzzle API","base":"https://arling.sk/api/puzzles/v1/","docs":"https://arling.sk/api/","embed":"https://arling.sk/embed/puzzle/","updated":"2026-09-17","licence":{"free":"personal and non-commercial use with the credit line Puzzle by ARLing, arling.sk","commercial":"Puzzle Post Bulletin Pro subscription","url":"https://arling.sk/puzzle-post/bulletin/"},"difficulties":["easy","medium","hard"],"perDifficulty":200,"total":6000,"kinds":[{"kind":"hedgehogs","name":"Hedgehogs","type":"Star Battle","rules":["Two hedgehogs go in every row, in every column and in every flowerbed. The flowerbeds are the outlined shapes, and a garden with eight rows has eight columns and eight flowerbeds, so sixteen hedgehogs in all.","No two hedgehogs may touch, not side by side and not diagonally. Every hedgehog keeps the eight cells around it empty.","Exactly one arrangement fits. Mark the cells you have ruled out however you like; only the hedgehogs count."],"rulesUrl":"https://arling.sk/games/hedgehogs/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[9],"index":"hedgehogs/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[9],"index":"hedgehogs/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[10],"index":"hedgehogs/hard/index.json"}]},{"kind":"magpies","name":"Magpies","type":"Nonograms","rules":["The numbers beside every row and above every column give the lengths of the blocks of filled cells, in order, with at least one empty cell between two blocks.","A filled cell is a cell a magpie left something shiny in. An empty cell is nothing. Work out from the numbers alone which is which.","Exactly one picture fits every number, and it can always be reached by reasoning, never by guessing. A cross is your own note that a cell stays empty."],"rulesUrl":"https://arling.sk/games/magpies/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[8],"index":"magpies/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[10],"index":"magpies/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[12],"index":"magpies/hard/index.json"}]},{"kind":"otters","name":"Otters","type":"Slitherlink","rules":["Draw one closed loop along the grid lines. The otters need a single river: no branches, no crossings, no second loop.","A number in a patch counts its sides. It says how many of that patch’s four sides the river runs along, from 0 to 3. A patch with no number says nothing at all.","Exactly one loop fits every number. A cross on a side is your own note that the side stays dry."],"rulesUrl":"https://arling.sk/games/otters/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[5],"index":"otters/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[6],"index":"otters/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[7],"index":"otters/hard/index.json"}]},{"kind":"squirrels","name":"Squirrels","type":"Kakuro","rules":["Squirrels hide acorns in the hollows. Each sign tells how many acorns are in the run of hollows to its right or below it. A run is the unbroken line of hollows that follows a sign and ends at the next trunk or at the edge of the wood.","Every hollow holds 1 to 9 acorns, and no number repeats within a run. Every hollow belongs to one run across and one run down at the same time, so the number you write has to suit both.","Exactly one filling fits every sign."],"rulesUrl":"https://arling.sk/games/squirrels/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[6],"index":"squirrels/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[8],"index":"squirrels/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[10],"index":"squirrels/hard/index.json"}]},{"kind":"cranes","name":"Cranes","type":"Hashi","rules":["Join the sandbanks with straight walkways. A walkway runs up and down or left and right, and only between two sandbanks that stand in line with nothing in between.","A number on a sandbank counts its walkways. When it says four, exactly four walkways leave it. Two walkways may run side by side between the same pair, and that counts as two.","Walkways never cross, and when the water is finished every sandbank can be reached from every other."],"rulesUrl":"https://arling.sk/games/cranes/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[7],"index":"cranes/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[9],"index":"cranes/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[11],"index":"cranes/hard/index.json"}]},{"kind":"swans","name":"Swans","type":"Masyu","rules":["Draw one loop through every swan. The loop runs from the middle of one cell to the middle of the next, up and down or left and right, never diagonally, and it never crosses itself, branches, or passes through the same cell twice.","A white swan means the loop goes straight through it and turns in the cell just before or just after. A black swan means the loop turns in that cell and goes straight through both neighbouring cells.","Cells with no swan may be left out of the loop altogether. Exactly one loop fits every swan."],"rulesUrl":"https://arling.sk/games/swans/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[6],"index":"swans/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[7],"index":"swans/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[8],"index":"swans/hard/index.json"}]},{"kind":"voles","name":"Voles","type":"Nurikabe","rules":["Every number is a vole family, and it says how big their island is, the number’s own cell included. Shade the rest of the meadow as water so that every island holds exactly one number and exactly that many cells.","Islands never touch by a side. Two islands may sit corner to corner, never side by side, or they would be one island with two numbers.","The water always hangs together as a single sheet, and no two by two block is ever all water."],"rulesUrl":"https://arling.sk/games/voles/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[6],"index":"voles/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[8],"index":"voles/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[10],"index":"voles/hard/index.json"}]},{"kind":"badgers","name":"Badgers","type":"Killer Sudoku","rules":["Every row, every column and every block holds each number once. The grid size sets the numbers: six by six uses 1 to 6, nine by nine uses 1 to 9. A block is the small rectangle marked by the thicker line.","The dotted cages add up. A cage is the group of cells inside one dotted outline, and the small number in its top left corner is what its cells add up to, with no number repeated inside the cage.","Nothing is filled in at the start: the cages are the whole puzzle, and exactly one arrangement fits."],"rulesUrl":"https://arling.sk/games/badgers/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[6],"index":"badgers/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[9],"index":"badgers/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[9],"index":"badgers/hard/index.json"}]},{"kind":"herons","name":"Herons","type":"Numberlink","rules":["Every pair of nests belongs to one pair of herons. Draw a flight path between the two nests of every pair. A path steps from one cell to the next, up and down or left and right, never diagonally, and it never runs beside itself.","Paths never cross. Once a cell belongs to one path it is closed to every other.","Every cell of the marsh is used: no cell is left over when the marsh is finished."],"rulesUrl":"https://arling.sk/games/herons/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[5],"index":"herons/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[6],"index":"herons/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[7],"index":"herons/hard/index.json"}]},{"kind":"hares","name":"Hares","type":"Anti-knight Sudoku","rules":["Every row, every column and every block holds each number once. A meadow with nine rows has nine columns and nine blocks of three by three; a six by six meadow has blocks of two rows by three columns.","Hares leap like a knight. Two burrows a knight’s leap apart, two one way and one across, never hold the same number. The leap reaches over rows, columns and blocks alike.","In the harder meadows hares also refuse to sit next to the same number in any direction, corners included. Each puzzle says above it which rules are in force."],"rulesUrl":"https://arling.sk/games/hares/guide/","difficulties":[{"difficulty":"easy","count":200,"sizes":[6],"index":"hares/easy/index.json"},{"difficulty":"medium","count":200,"sizes":[9],"index":"hares/medium/index.json"},{"difficulty":"hard","count":200,"sizes":[9],"index":"hares/hard/index.json"}]}],"today":{"path":"today/<kind>.json","note":"The puzzle the daily game shows today, rebuilt every night. Same schema, with an extra date field."},"schema":{"file":"<kind>/<difficulty>/<index>.json, index padded to three digits","fields":{"v":"schema version, currently 1","kind":"badgers, hares, squirrels, magpies, hedgehogs, otters, cranes, swans, voles, herons","difficulty":"easy, medium or hard","id":"<kind>-<difficulty>-<index>","seed":"the deterministic key the puzzle was generated from","size":"n, the side of the grid","rules":"the puzzle type and a link to the full rules","givens":"the clues as a flat array, for the kinds that have one (see givens below)","grid":"the clues that are not a flat array: cages, clues, islands, regions, stars, rules, pairs","solution":"{ cells } for grid kinds, { h, v } for the loop kinds otters and swans, { bridges } for cranes","verified":"{ uniqueSolution, solverMs }: our solver found exactly one answer and it matches the clues","licence":"the free and the commercial licence","svg":"file names of the puzzle and solution drawings, next to the JSON"},"givens":{"hares":"flat n*n array, 0 for an empty cell","squirrels":"flat n*n array, null for a trunk or { r, d } for the across and down sums","hedgehogs":"n arrays of n region numbers","otters":"flat n*n array of 0 to 3 or null","swans":"flat n*n array, 0 nothing, 1 white, 2 black","voles":"flat n*n array, the island size or null","herons":"flat n*n array, 0 or the number of the pair whose nest is there"},"grid":{"badgers":"{ cages: [{ sum, cells }] }","magpies":"{ clues: { rows, cols } }","cranes":"{ islands: [{ r, c, n }] }","hedgehogs":"{ stars: hedgehogs per row, column and flowerbed }","hares":"{ rules: { knight, king } }","herons":"{ pairs: how many pairs of nests }"},"notes":["Every file is static. There are no keys, no rate limits and no server.","The drawings are SVG without width or height, only a viewBox, so they scale to any size.","The same puzzle never appears in a daily game, a book, an edition, a Puzzle Planner pack or a Puzzle Post issue.","Our check is: exactly one solution for our solver, and the answer matches every clue. It is not a claim of worldwide novelty."]}}