Regex Tester

Test, highlight, and learn regular expressions.

Pattern

//g

Global (g) is always on. Flags:iignore casemmultilinesdotall

Test string

2 matches

Contact [email protected] or jo.[email protected] for details.
Not an email: hello world.

Match	Group 1	Group 2
[email protected]	sam	example.com
[email protected]	doe	mail.co.uk

What your pattern means

(Start of a capturing group
\wAny word character (a–z, A–Z, 0–9, _)
+One or more (greedy)
)End of group
@Literal "@"
(Start of a capturing group
\wAny word character (a–z, A–Z, 0–9, _)
[\w.]Any character in the set [\w.]
*Zero or more (greedy)
\.Literal "."
\wAny word character (a–z, A–Z, 0–9, _)
+One or more (greedy)
)End of group

Regex cheat sheet — symbols, meanings, and examples

Character classes

.Any character except newline— a.c → abc, a2c
\dA digit (0–9)— \d\d → 42
\wWord character (a–z, 0–9, _)— \w+ → hello_1
\sWhitespace (space, tab, newline)— a\sb → 'a b'
[abc]Any one of a, b, or c— [aeiou] → a vowel
[^abc]Any character except a, b, c— [^0-9] → non-digit
[a-z]A range of characters— [A-Z] → any capital

Anchors & boundaries

^Start of the string / line— ^Hi → line starting 'Hi'
$End of the string / line— end$ → line ending 'end'
\bA word boundary— \bcat\b → the word 'cat'

Quantifiers

*Zero or more— ab* → a, ab, abbb
+One or more— ab+ → ab, abbb
?Optional (zero or one)— colou?r → color, colour
{3}Exactly 3 times— \d{3} → 123
{2,4}Between 2 and 4 times— \d{2,4} → 12–1234
*?Lazy — as few as possible— <.*?> → shortest tag

Groups & alternation

(abc)Capturing group— (ab)+ → abab
(?:abc)Non-capturing group— (?:ab)+ → groups without capturing
(?<name>…)Named capturing group— (?<year>\d{4})
a|bMatch a OR b— cat|dog → cat, dog
(?=…)Lookahead (followed by)— \d(?=px) → digit before 'px'

Flags

gGlobal — find all matches— /a/g
iCase-insensitive— /abc/i → ABC
mMultiline — ^ and $ per line— /^x/m
sDotall — . matches newline too— /a.b/s

Runs entirely in your browser — nothing you enter is uploaded or sent to a server.

Patterns run on your browser's JavaScript regex engine, so they behave as they do in JavaScript — other flavours (PCRE, Python, Go) differ in places, so test in your target language before you rely on one. Read our full disclaimer.

About this tool

A regex playground built for both getting work done and learning. Type a pattern and sample text and it highlights every match live, lists the capture groups, and — crucially — explains your pattern in plain English, token by token. A built-in cheat sheet covers the common symbols with meanings and examples, so you can practise and understand what each piece does. Toggle the i, m, and s flags as needed. It runs on your browser's native regular-expression engine.

Try it

The pattern (\w+)@(\w[\w.]*\.\w+) finds emails and captures the name and domain as groups. The breakdown explains each symbol; the cheat sheet shows more.

How to use

1Type your regular expression in the pattern box.
2Toggle flags (ignore case, multiline, dotall) — global is always on.
3Enter or paste the text to test against and see matches highlighted.
4Read the plain-English breakdown of your pattern, and open the cheat sheet to learn more.

Features

Live match highlighting with a capture-group breakdown.
Plain-English explanation of your pattern, token by token.
A learn-by-example cheat sheet of common symbols.
Toggle the i, m, and s flags (global is always on).

Frequently asked questions

Which regex flavour does it use?

JavaScript's built-in regular expression engine, running in your browser. Patterns behave exactly as they would in JavaScript.

Is the global flag always on?

Yes — the tester finds all matches, so it always uses the global flag. You can additionally toggle ignore-case (i), multiline (m), and dotall (s).

How do I test a regex against my text?

Type your pattern in the pattern box and paste your text below; every match is highlighted live and the capture groups are listed. Toggle the i/m/s flags as needed — the global flag is always on, so you see all matches, not just the first.

Why does my regex work here but not in Python or PHP?

This uses JavaScript's regex engine. Other flavours — PCRE in PHP, Python's re, Go — differ on things like lookbehind, named groups, and Unicode handling, so always test a pattern in your target language before relying on it.

Can it explain any pattern?

It breaks down the common metacharacters, quantifiers, groups, and character classes in plain English. It's a learning aid, so extremely exotic constructs may be labelled generically.

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