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Regex Cheat Sheet

Searchable reference for regular expression syntax with examples and one-click copy.

Anchors4 patterns

Pattern	Description	Example
`^`	Start of string (or line in multiline mode)	^Hello matches 'Hello world'
`$`	End of string (or line in multiline mode)	world$ matches 'Hello world'
`\b`	Word boundary \| transition between \w and \W	\bcat\b matches 'cat' but not 'catfish'
`\B`	Non-word boundary	\Bcat\B matches 'scattered'

Character Classes9 patterns

Pattern	Description	Example
`\d`	Any digit \| equivalent to [0-9]	\d+ matches '42' in 'foo42bar'
`\w`	Word character \| [a-zA-Z0-9_]	\w+ matches 'hello_2'
`\s`	Whitespace \| space, tab, newline, etc.	\s+ matches spaces and tabs
`\D`	Non-digit \| [^0-9]	\D+ matches 'abc' in 'abc123'
`\W`	Non-word character \| [^a-zA-Z0-9_]	\W matches '!' in 'hello!'
`\S`	Non-whitespace character	\S+ matches 'hello' (no spaces)
`[abc]`	Character set \| matches a, b, or c	[aeiou] matches any vowel
`[^abc]`	Negated set \| matches anything except a, b, or c	[^0-9] matches any non-digit
`[a-z]`	Range \| any lowercase letter a through z	[a-zA-Z] matches any letter

Quantifiers8 patterns

Pattern	Description	Example
`*`	Zero or more of the preceding element	a* matches '', 'a', 'aaa'
`+`	One or more of the preceding element	a+ matches 'a', 'aaa' but not ''
`?`	Zero or one \| makes preceding element optional	colou?r matches 'color' and 'colour'
`{n}`	Exactly n repetitions	\d{4} matches exactly 4 digits
`{n,}`	n or more repetitions	\w{3,} matches words with 3+ chars
`{n,m}`	Between n and m repetitions (inclusive)	\d{2,4} matches 2 to 4 digits
`*?`	Lazy (non-greedy) zero or more \| matches as few as possible	<.+?> matches each tag individually
`+?`	Lazy one or more \| matches as few as possible	a+? matches only the first 'a'

Groups & Lookaround6 patterns

Pattern	Description	Example
`(abc)`	Capturing group \| captures the match for back-reference	(\d+) captures the number
`(?:abc)`	Non-capturing group \| groups without capturing	(?:foo\|bar)+ matches 'foobar'
`(?=abc)`	Positive lookahead \| matches if followed by abc	\d+(?= dollars) matches digits before ' dollars'
`(?!abc)`	Negative lookahead \| matches if NOT followed by abc	\d+(?! dollars) matches digits not before ' dollars'
`(?<=abc)`	Positive lookbehind \| matches if preceded by abc	(?<=\$)\d+ matches digits after '$'
`(?<!abc)`	Negative lookbehind \| matches if NOT preceded by abc	(?<!\$)\d+ matches digits not after '$'

Common Patterns8 patterns

Pattern	Description	Example
`^[\w.+-]+@[\w-]+\.[\w.]+$`	Email address (basic validation)	user@example.com
`https?:\/\/[\w\-._~:/?#[\]@!$&'()*+,;=%]+`	URL (http or https)	https://example.com/path?q=1
`^(\+1)?[-.\s]?\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$`	US phone number (various formats)	(555) 867-5309 or 555-867-5309
`^\d{4}-(0[1-9]\|1[0-2])-(0[1-9]\|[12]\d\|3[01])$`	ISO date YYYY-MM-DD	2024-01-15
`^((25[0-5]\|2[0-4]\d\|[01]?\d\d?)\.){3}(25[0-5]\|2[0-4]\d\|[01]?\d\d?)$`	IPv4 address	192.168.1.1
`^#([0-9a-fA-F]{3}\|[0-9a-fA-F]{6})$`	Hex color code	#fff or #3b82f6
`^\d{5}(-\d{4})?$`	US ZIP code (5 or 9 digit)	90210 or 90210-1234
`^4[0-9]{12}(?:[0-9]{3})?$`	Visa credit card number	4111111111111111