Regex Dojo
Write regex patterns to match green strings and reject red ones.
Regex Dojo
Write regex patterns to match green strings and reject red strings. Progress through 20 levels — from simple literals to lookaheads.
How to Play Regex Dojo
- Read the challenge description — for example, "match all email addresses" or "match lines starting with a digit".
- Write a regex pattern in the input field to satisfy the challenge.
- The game highlights which test strings your pattern matches — green for correct matches, red for false positives.
- You must match all required strings without matching any of the forbidden ones to pass the challenge.
- Advance through 30+ progressively complex challenges, from literal matches to lookaheads and backreferences.
About Regex Dojo
Regex Dojo teaches regular expression syntax through hands-on challenges. Starting from simple literal matches and character classes, it builds progressively to lookaheads, backreferences, and complex multi-pattern expressions. Each challenge presents a set of strings to match and a set to reject — your regex must thread the needle between them. Instant visual feedback highlights matches in green and false positives in red.
A reference panel shows common syntax at a glance for learners. Ideal for developers learning regex or experienced engineers sharpening their pattern-writing instincts. Free in your browser, no download required.