Regex Crossword

Fill a letter grid so every row matches its row regex and every column matches its column regex. Offline-first, 100% client-side Vanilla JS with zero dependencies.

Fill the grid so every row and column matches its regex.
Row patterns
Row 1: ^[A-Z]{3}$
Row 2: ^B[A-Z]R$
Row 3: ^D[A-Z]G$
Column patterns
Col 1: ^[CBD]{3}$
Col 2: ^[AEIOU]{3}$
Col 3: ^[TRG]{3}$
100% client-side · no network · Vanilla JS · RegExp
Reserved for AdSense (Horizontal)

Use Cases

Regex Crossword is a logic puzzle that combines the structure of a crossword with regular expressions. Players fill a letter grid so that every row reads as a string matching its assigned row pattern, and every column reads as a string matching its assigned column pattern. It is an engaging way for developers, students, and puzzle enthusiasts to practice reading and writing regular expressions in a visual, constraint-driven format.

Because Regex Crossword runs entirely in the browser with zero external dependencies, it works offline, requires no account, and keeps all puzzle state local to your device.

How to Play Regex Crossword

  • Objective: Enter exactly one letter into each empty box so that the letters in every row, read left-to-right, form a string that matches that row's regex pattern, and the letters in every column, read top-to-bottom, form a string that matches that column's regex pattern.
  • Row patterns: Each row has a pattern shown at the top of the grid. The three letters you type in that row must, when read left-to-right, satisfy that pattern.
  • Column patterns: Each column has a pattern shown at the top of the grid. The three letters you type in that column must, when read top-to-bottom, satisfy that pattern.
  • Input: Click or tap a box and type a single letter. Only A-Z is accepted; the entry is converted to uppercase automatically. The puzzle is solved when every box is filled and every row and column matches its pattern.
  • Checking your work: Click Check Solution to validate the grid. Correct cells highlight green; incorrect or empty cells highlight red so you can fix them.
  • Reset: Click Reset to clear the grid and start over.

Regex Cheat Sheet

The puzzle uses these common regular expression symbols:

  • ^ — Start of string anchor. Asserts that the match must begin at the very first character of the string.
  • $ — End of string anchor. Asserts that the match must end at the very last character of the string.
  • [A-Z] — Character class. Matches any single uppercase letter from A to Z.
  • {3} — Quantifier. Matches exactly three of the preceding token (for example, [A-Z]{3} matches exactly three uppercase letters).

Example pattern: ^[A-Z]{3}$ means "exactly three uppercase letters, from start to end" — which describes any three-letter row such as CAT or DOG.

Regex Crossword is a 100% client-side game built with Vanilla JS and the native RegExp engine. No server, no network, no uploads — play it anywhere, entirely offline.

Frequently Asked Questions