How do I test a regular expression?

Enter your pattern, choose flags (global, ignore case, multiline, etc.), then paste text in the test string area. Matches are highlighted in amber. Use multiple test strings (one per line) to check many inputs at once.

Can I share my regex and test text?

Yes. Click Share URL to copy a link that encodes your pattern, test text, line tests, and flags in the query string.

Which regex flavor does this tester use?

JavaScript (ECMAScript) regular expressions—the same as in browsers and Node.js. Flags include global (g), ignore case (i), multiline (m), dotAll (s), and unicode (u).

Is the regex tester free for developers?

Yes. It is free to use with no account. All processing runs in your browser.

Regex Tester

Test JavaScript regular expressions with live match highlighting, a match list, and multiple test strings (one per line).

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Test string

Match highlighting

Matches will appear here.

Multiple test strings (one per line)

Regex symbols reference

Each symbol with a short description and example of what it matches.

▸Anchors & boundaries

Symbol	Description	Example pattern	Matches (idea)
^	Start of string (start of each line with m flag).	^Hello	"Hello" at start of text
$	End of string (end of each line with m flag).	end$	text ending in "end"
\b	Word boundary (between word \w and non-word).	\bcat\b	"cat" as whole word, not "category"
\B	Not a word boundary.	\Bcat	"cat" inside a word, e.g. "vacation"

▸Character classes

Symbol	Description	Example pattern	Matches (idea)
.	Any single character except newline (with s flag, includes newline).	a.c	"abc", "a1c" — not "a\nc"
\d	Digit 0–9.	\d{3}	"123" — three digits in a row
\D	Any non-digit.	\D+	runs of letters/symbols between numbers
\w	Word character: letter, digit, or underscore.	\w+	"foo", "x_1"
\W	Non-word character (spaces, punctuation).	\W	space, comma, @, etc.
\s	Whitespace (space, tab, newline, etc.).	\s+	one or more spaces/tabs
\S	Non-whitespace.	\S+	first "word" without spaces
[ ]	Any one character inside brackets.	[aeiou]	any single vowel
[^ ]	Any character NOT in brackets.	[^0-9]	any char that is not a digit
[a-z]	Range inside brackets.	[A-Z][a-z]+	"Hello" style capital + lowercase

▸Quantifiers (how many times)

Symbol	Description	Example pattern	Matches (idea)
*	Zero or more of the previous.	ab*c	"ac", "abc", "abbbc"
+	One or more of the previous.	\d+	"42", "007" — not ""
?	Zero or one (optional).	colou?r	"color" or "colour"
{n}	Exactly n times.	\d{4}	exactly 4 digits, e.g. year
{n,}	At least n times.	\w{3,}	words with 3+ letters
{n,m}	Between n and m times.	\d{1,3}	1 to 3 digits
*? +? ??	Lazy (non-greedy): as few repeats as possible.	<.*?>	shortest span inside < >

▸Groups & alternation

Symbol	Description	Example pattern	Matches (idea)
( )	Capturing group; remembers match for \1, \2….	(\w+)\s+\1	repeated word: "hi hi"
(?: )	Non-capturing group (grouping only).	(?:https?:)//	"http://" or "https://"
\|	OR — match left or right side.	cat\|dog	"cat" or "dog"
(?= )	Positive lookahead: followed by pattern without consuming.	\d(?=px)	digit only if "px" follows
(?! )	Negative lookahead: not followed by.	\d(?!px)	digit not before "px"
(?<= )	Positive lookbehind (fixed length in some engines).	(?<=@)\w+	word after @
(?<! )	Negative lookbehind.	(?<!\$)\d+	digits not after $

▸Escaping & literals

Symbol	Description	Example pattern	Matches (idea)
\	Escape special characters to match them literally.	\.	a literal dot, not "any char"
\.	Literal period.	file\.txt	"file.txt"
\* \^ \$ etc.	Special chars need \ when you want the character itself.		literal parentheses

▸Common escapes

Symbol	Description	Example pattern	Matches (idea)
\n	Newline character.	line\nline	two lines separated by newline
\t	Tab.	\t+	one or more tabs
\\	Backslash in pattern (in JS string often "\\").	C:\\Users	Windows-style path segment

▸Flags (checkboxes above)

Symbol	Description	Example pattern	Matches (idea)
g	Global — find all matches, not just the first.	/\w+/g	every word in the string
i	Ignore case — A equals a.	/hello/i	"Hello", "HELLO"
m	Multiline — ^ and $ match each line.	^#	start of every line
s	DotAll — . matches newline too.	.*	entire block including line breaks
u	Unicode mode — correct handling of surrogate pairs, \u{…}.	with u flag	full Unicode code points, not half-pairs

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How to use

Enter your pattern (JavaScript regex syntax).
Toggle flags: g for all matches, i for case-insensitive, m for multiline ^/$, s for dotAll, u for Unicode.
Paste text in Test string to see highlighted matches and a match table.
Use Multiple test strings to validate one pattern against many lines.
Share URL copies a link with your pattern and sample text encoded.
Expand Regex symbols reference below the tool for each symbol, description, and example.