Regex Cheat Sheet — 20 Common Patterns with Examples You Can Test

Twenty regex patterns you will actually use. Each one includes the pattern, what it matches, and a test example. Copy any pattern and test it instantly against your own data.

Text & Validation Patterns

#	Pattern Name	Regex	Example Match
1	Email address	[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}	[email protected]
2	URL (http/https)	https?://[^\\s/$.?#][^\\s]*	https://example.com/page?q=1
3	IPv4 address	\\b\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\b	192.168.1.1
4	US phone number	\\(?\\d{3}\\)?[-.\\s]?\\d{3}[-.\\s]?\\d{4}	(555) 123-4567
5	Date (YYYY-MM-DD)	\\d{4}-\\d{2}-\\d{2}	2026-04-01
6	US zip code	\\d{5}(-\\d{4})?	90210, 90210-1234
7	Hex color code	#[0-9a-fA-F]{3,8}	#FF5733, #fff, #00aaff80

Data Extraction Patterns

#	Pattern Name	Regex	Example Match
8	HTML tags	<[^>]+>	<div class="box">, <br/>
9	Username (alphanumeric)	^[a-zA-Z0-9_]{3,20}$	cool_user_42
10	Password strength (8+ chars, upper, lower, digit)	^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d).{8,}$	MyPass123
11	Credit card (basic 16 digits)	\\b\\d{4}[- ]?\\d{4}[- ]?\\d{4}[- ]?\\d{4}\\b	4111-1111-1111-1111
12	File extension	\\.([a-zA-Z0-9]{1,10})$	.pdf, .jpg, .html
13	Trim whitespace	^\\s+|\\s+$	Leading/trailing spaces
14	Duplicate consecutive words	\\b(\\w+)\\s+\\1\\b	the the, is is

Developer & Content Patterns

#	Pattern Name	Regex	Example Match
15	Markdown link	\\[([^\\]]+)\\]\\(([^)]+)\\)	[text](https://url.com)
16	CSV value (quoted)	"([^"]*)"	"John Smith","New York"
17	JSON key	"([^"]+)"\\s*:	"name": "value"
18	URL slug	^[a-z0-9]+(-[a-z0-9]+)*$	my-blog-post-title
19	Emoji (Unicode range)	[\\u{1F600}-\\u{1F64F}]	Matches face emojis
20	Hashtag	#[a-zA-Z0-9_]+	#regex, #coding, #dev_tools

How to Use This Cheat Sheet

1. Find the pattern you need from the tables above
2. Copy the regex pattern
3. Open Regex Tester
4. Paste the pattern and your test data
5. Verify it matches what you expect (and does not match what it should not)
6. Copy the working pattern into your code

Always test against edge cases, not just the happy path. An email regex that matches "[email protected]" might also match "[email protected]" if you are not careful.

Quick Syntax Reference

Symbol	Meaning	Example
\\d	Any digit (0-9)	\\d{3} matches 123
\\w	Word character (letter, digit, underscore)	\\w+ matches hello_42
\\s	Whitespace (space, tab, newline)	\\s+ matches any whitespace run
.	Any character (except newline without s flag)	a.c matches abc, a1c, a-c
+	One or more of previous	\\d+ matches 1, 42, 999
*	Zero or more of previous	\\d* matches empty string or digits
?	Zero or one of previous (also: lazy modifier)	colou?r matches color and colour
{n,m}	Between n and m repetitions	\\d{2,4} matches 42, 123, 1234
^	Start of string (or line with m flag)	^ matches start of string
$	End of string (or line with m flag)	$ matches end of string
[abc]	Character class: a, b, or c	[aeiou] matches any vowel
[^abc]	Negated class: NOT a, b, or c	[^0-9] matches non-digits
(abc)	Capture group	(\\d+)-(\\d+) captures both numbers
a|b	Alternation: a or b	cat|dog matches either word
\\b	Word boundary	\\bcat\\b matches cat but not catalog

Related Developer Tools

• Regex Tester — test any pattern from this cheat sheet
• JSON Formatter — format JSON data you are parsing
• Code Formatter — clean up code with regex patterns
• Find & Replace — apply regex-based search and replace
• Meta Tag Generator — generate meta tags for your pages