Regular expressions are patterns used to match character combinations in strings. This tool helps you:
- Test regex patterns against sample text
- Debug complex expressions with highlighted matches
- Generate common patterns for emails, URLs, dates, etc.
- Learn with our comprehensive regex cheatsheet
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Regex Cheatsheet
Quick reference for common regex patterns and syntax:
| Pattern | Description | Example |
|---|---|---|
\d |
Digit (0-9) | \d{3} matches "123" |
\w |
Word character (a-z, A-Z, 0-9, _) | \w+ matches "hello" |
\s |
Whitespace (space, tab, newline) | \s matches " " |
. |
Any character except newline | a.c matches "abc" |
^ |
Start of string/line | ^Start matches start of line |
$ |
End of string/line | end$ matches end of line |
[abc] |
Any of a, b, or c | [aeiou] matches vowels |
[^abc] |
Not a, b, or c | [^0-9] matches non-digits |
* |
0 or more repetitions | a* matches "", "a", "aa", etc. |
+ |
1 or more repetitions | \d+ matches "1", "123", etc. |
? |
0 or 1 repetition | colou?r matches "color" or "colour" |
{n} |
Exactly n repetitions | \d{3} matches "123" |
{n,} |
n or more repetitions | \d{2,} matches "12", "123", etc. |
{n,m} |
Between n and m repetitions | \d{2,4} matches "12", "123", "1234" |
(...) |
Capture group | (abc) captures "abc" |
(a|b) |
a or b | (cat|dog) matches "cat" or "dog" |
\b |
Word boundary | \bword\b matches whole word |
\B |
Not word boundary | \Bword\B matches inside words |