Regex Tester

Test a regular expression and inspect its matches and groups

Expression

/ /g

g global i ignore case m multiline s dot all u unicode y sticky

Test string

The expression took more than a second and was stopped. It probably backtracks catastrophically, as nested quantifiers like (a+)+ do.

Matches

#	Position	Match	Groups

Replace

$1, $2… insert a group, $<name> a named group, $& the whole match, $$ a dollar sign.

Cheat sheet

.: Any character except a line break (any at all with the s flag)
\d \w \s: Digit, word character [A-Za-z0-9_], whitespace; \D \W \S negate them
[abc] [^abc] [a-z]: One of, none of, a range
^ $ \b: Start, end (of a line with the m flag), word boundary
* + ? {2,5}: 0 or more, 1 or more, optional, between 2 and 5; add ? to match as few as possible
(…) (?<name>…) (?:…): Capturing group, named group, non-capturing group
a|b: a or b
(?=…) (?!…) (?<=…) (?<!…): Followed by, not followed by, preceded by, not preceded by
\1 \k<name>: The text matched by group 1, by a named group
\p{L}: A Unicode letter, with the u flag (also \p{N}, \p{Emoji}…)