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🔤 Regex Puzzle — Learn Regular Expressions

Regex Puzzle is a free learn-regex game (RegexGolf style): write one pattern that matches every string on the left and rejects every one on the right. Master character classes, anchors, quantifiers and alternation level by level — tested live in your browser, no download.

Level 1 / 12

Write one regular expression that matches every string on the left and none on the right.

✅ Must MATCH

✗ cat
✗ category
✗ scatter

🚫 Must NOT match

✓ dog
✓ bird
✓ fish

💡 Hint: Just type the letters you want to find. A plain word is already a regex.

🎓 What you learn

Literals & character classes [ ]
Anchors ^ and $
Quantifiers + * ? and \d \w
Alternation | and the wildcard .

❓ Frequently Asked Questions

Is Regex Puzzle free?

Yes — it runs entirely in your browser, 100% free, no download and no sign-up.

What is a regular expression?

A regex is a compact pattern for matching text — used in search, validation and coding. This game teaches it hands-on, level by level.

Does it run real regex?

Yes. Your pattern is compiled with the browser's native RegExp engine and tested live against each string, so what you learn transfers straight to real code.