Regex Tester

Write a regex pattern, toggle flags, and see matches highlighted instantly in your test string. Each match shows its index position and capture groups. A collapsible cheat sheet keeps common syntax at your fingertips.

Pattern

//g

Test String

Match Highlights

Matches (2)

"hello@example.com"index 14

"support@toolzhq.com"index 35

Character Classes

\dDigit (0-9)

\wWord char (a-z, A-Z, 0-9, _)

\sWhitespace

.Any character (except newline)

\DNon-digit

\WNon-word character

\SNon-whitespace

Quantifiers

*0 or more

+1 or more

?0 or 1

{n}Exactly n

{n,}n or more

{n,m}Between n and m

Anchors

^Start of string

$End of string

\bWord boundary

\BNon-word boundary

Groups & Lookahead

(abc)Capture group

(?:abc)Non-capture group

(?=abc)Positive lookahead

(?!abc)Negative lookahead

(?<=abc)Positive lookbehind

(?<!abc)Negative lookbehind

a|bAlternation

How it works

The tester compiles your pattern into a JavaScript RegExp object with the selected flags. It then runs exec() in a loop to find every match in the test string. Matched portions are wrapped in highlighted spans while non-matched text is HTML-escaped to prevent XSS.

Results update in real time as you type. If your pattern contains a syntax error, a clear error message is shown instead of crashing. The flag checkboxes let you toggle global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u) modes.

The cheat sheet sidebar covers character classes, quantifiers, anchors, groups, and lookahead/lookbehind assertions — everything you need for day-to-day regex work without leaving the page.