How It Works
The engineering behind a personalized crossword constructor.
Freeform Strategies
When you generate a crossword, you can pick from three different placement strategies. Each one orders your words differently before handing them to the greedy placer, producing layouts with different characteristics.
Adjacency-Aware
Two-phase: places your words with parallel adjacencies, then fills perpendicular gaps with real dictionary words.
Read more →Parallel-Seeded
Starts with an optimal parallel word pair, then uses inline gap filling to build dense clusters incrementally.
Read more →Densest Crossings
Builds a graph of word connections and prioritizes the most interconnected words.
Read more →Longest First
Places longer words first as anchors, then fits shorter words around them.
Read more →Balanced
Hybrid: starts with the longest word, then prioritizes connected words.
Read more →The Block Builder
Work in ProgressThe Block Builder produces newspaper-style grids with dense black squares and dictionary fill. It runs in three phases: scaffold the user's words via the freeform solver, carve out a structured grid by progressively marking cells black, then fill every remaining slot with a real dictionary word.
The walkthrough below shows the distinguishing move: the shrink-and-carve structure phase, where an open canvas is shaped into a proper crossword grid before any fill happens.
1. Place the user's words
1 / 6Phase 1 hands the user's three words (CORAL, TIDE, REEF) to the freeform scaffold solver. The solver lays them out so they intersect: REEF crosses CORAL at R and crosses TIDE at E. CORAL's O sits right beside TIDE's D at row 3, which means the algorithm gets an OD across word for free without ever placing it. Every other cell is open canvas, waiting to be carved or filled.
The Guided Builder
Freeform mode builds the grid around your words. The Guided Builder works the opposite way: you start with a fixed grid pattern (5×5, 7×7, or 15×15), and the engine helps you place words slot by slot. It's the right tool when you want a traditional NYT-style crossword shape.
Two-Layer Word Source
Your themed words are prioritized because they're the answers you care about. A built-in 42K-word crossword dictionary (Collaborative Word List, MIT-licensed) handles the structural fill.
Real-Time Constraint Propagation
Click any slot to see every word that could fit, given the letters already placed at crossing points. Pick one, and all intersecting slots update instantly using AC-3 arc consistency.
Editable Grid Pattern
Toggle any cell black or white to shape the grid. Optional 180° rotational symmetry mimics the standard NYT layout, or turn it off for fully custom shapes.
Auto-Fill the Remainder
Place a few key answers manually, then let the CSP solver fill the rest. The solver prioritizes your themed words and uses the dictionary for the structural fill.