Regex Cheat Sheet 2026: The Complete Regular Expression Reference

Regular expressions (regex) are powerful pattern-matching tools used in programming, text editors, and command-line utilities. This cheat sheet covers the syntax you need, with copy-paste ready patterns for common use cases.

Basic Syntax

Symbol	Meaning	Example	Matches
.	Any single character	h.t	hat, hot, h9t
^	Start of string	^Hello	"Hello world" but not "Say Hello"
$	End of string	world$	"Hello world" but not "worlds"
*	0 or more	ab*c	ac, abc, abbc, abbbc
+	1 or more	ab+c	abc, abbc (not ac)
?	0 or 1 (optional)	colou?r	color, colour
{n}	Exactly n times	a{3}	aaa
{n,m}	Between n and m times	a{2,4}	aa, aaa, aaaa

Character Classes

Class	Meaning	Equivalent
\d	Any digit	[0-9]
\D	Any non-digit	[^0-9]
\w	Word character	[a-zA-Z0-9_]
\W	Non-word character	[^a-zA-Z0-9_]
\s	Whitespace	[ \t\n\r\f]
\S	Non-whitespace	[^ \t\n\r\f]
[abc]	Any of a, b, or c	—
[^abc]	Not a, b, or c	—
[a-z]	Range: a through z	—

Common Patterns (Copy-Paste Ready)

Email Validation

^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$

Matches most standard email addresses. For production use, consider a more comprehensive RFC 5322 pattern or use your language's email validation library.

URL

https?:\/\/[\w\-]+(\.[\w\-]+)+[\/\w\-._~:?#\[\]@!$&'()*+,;=]*

Phone Number (US)

^\+?1?[\s\-]?\(?\d{3}\)?[\s\-]?\d{3}[\s\-]?\d{4}$

Matches: (555) 123-4567, 555-123-4567, +1 555 123 4567

Date (YYYY-MM-DD)

^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$

IP Address (IPv4)

^(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)$

Strong Password

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$

Requires: lowercase, uppercase, digit, special character, 8+ characters.

Lookaheads and Lookbehinds

Type	Syntax	Meaning
Positive lookahead	X(?=Y)	X followed by Y
Negative lookahead	X(?!Y)	X not followed by Y
Positive lookbehind	(?<=Y)X	X preceded by Y
Negative lookbehind	(?	X not preceded by Y

Tips for Writing Better Regex

• Start simple: Build your pattern incrementally, testing at each step.
• Be specific: Use \d instead of . when you expect digits. More specific patterns are faster and less error-prone.
• Use non-greedy quantifiers: .*? instead of .* to match as little as possible.
• Comment complex patterns: Use the verbose flag (x in most languages) to add comments.
• Test with edge cases: Empty strings, special characters, very long input, and Unicode text.

Test your patterns live with our free regex tester — see matches highlighted in real-time as you type.