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g global i ignore case m multiline s dotAll u unicode

Replace:

Test String

1

Matches 0

Replace Result:

Match Table

Characters

. any character

\d digit [0-9]

\D non-digit

\w word [a-zA-Z0-9_]

\W non-word

\s whitespace

\S non-whitespace

\t tab

\n newline

[abc] character set

[^abc] negated set

[a-z] range

Quantifiers

* 0 or more

+ 1 or more

? 0 or 1

{n} exactly n

{n,} n or more

{n,m} between n and m

*? lazy (0+ fewest)

+? lazy (1+ fewest)

Groups

(abc) capture group

(?:abc) non-capturing

(?<name>) named group

\1 backreference

a|b alternation

Anchors

^ start of string

$ end of string

\b word boundary

\B non-word boundary

(?=...) lookahead

(?!...) neg. lookahead

(?<=...) lookbehind

(?<!...) neg. lookbehind

Flags

g global

i case-insensitive

m multiline ^ $

s dotAll (. = \n)

u unicode

Common Patterns

Copy As

History

About Regex Tester

Regex Tester - Online Regular Expression Tester

Test regular expressions with live matching, capture group extraction, substitution/replace, pattern explanation, and match table export. Includes a quick reference for regex syntax, common patterns library, history, and export to JavaScript, Python, Java, C#, and Perl formats.

Features

Live regex matching with highlighted results in the test string
Capture group extraction with named groups support
Substitution/replace with live result preview
Regex flags: global, case-insensitive, multiline, dotAll, unicode
Pattern explanation showing what each part of the regex does
Match table with export to CSV and TSV
Quick reference for characters, quantifiers, groups, anchors, and flags
Common patterns library for emails, URLs, IP addresses, and more
Copy regex as JavaScript, Python, Java, C#, or Perl format
Pattern history for quick access to previous expressions