Regex Tester

Test and debug regular expressions in real time. Enter a pattern and test string to see live match highlighting, capture groups, and a replace preview.

Regular Expression Pattern

Flags: g — Global i — Case-insensitive m — Multiline s — Dot-all

Test String

Match Highlight

#	Match	Index	Length

Run a pattern to see matches here.

Match #	Group 1	Group 2	Group 3

No capture groups found.

'What do the regex flags do?', 'answer' => 'The g (global) flag finds all matches instead of stopping at the first. The i (case-insensitive) flag makes the match ignore uppercase/lowercase. The m (multiline) flag makes ^ and $ match the start/end of each line. The s (dot-all) flag makes the dot (.) also match newline characters.'], ]" />

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Regex Quick Reference

Anchors

^ — start of string/line

$ — end of string/line

Quantifiers

* — 0 or more

+ — 1 or more

? — 0 or 1

{n} — exactly n

Character Classes

\d — digit [0-9]

\w — word char [a-zA-Z0-9_]

\s — whitespace

. — any char (except \n)

Groups

(abc) — capture group

(?:abc) — non-capturing

(?=abc) — lookahead