This regex cheat sheet is a quick reference for the most commonly used regular expression syntax. It covers character classes, quantifiers, anchors, groups, and flags, plus ready-to-copy patterns.
If you want to test any pattern live, use our tool: Regex Tester.
Regex basics
Literal characters
hello
Matches the exact text hello.
Any character
.
Matches any character (except newline unless using the s flag).
Character classes
Digit, non-digit
\d \D
\d matches a digit (0–9). \D matches anything that is not a digit.
Word, non-word
\w \W
\w matches letters, digits, and underscore. \W matches anything else.
Whitespace, non-whitespace
\s \S
\s matches spaces, tabs, and line breaks. \S matches anything that is not whitespace.
Custom sets and ranges
[abc] [a-z] [A-Z] [0-9]
Matches one character from the set or range.
Negated sets
[^abc]
Matches any character except a, b, or c.
Anchors
Start and end of string
^text$
^ anchors to the start. $ anchors to the end.
Word boundary
\bword\b
Matches whole words only (not substrings).
Quantifiers
Common quantifiers
* + ? {n} {n,} {n,m}
- * = 0 or more
- + = 1 or more
- ? = 0 or 1
- {n} = exactly n
- {n,} = at least n
- {n,m} = between n and m
Greedy vs lazy
.* .*?
.* is greedy. .*? is lazy (stops as soon as possible).
Groups and alternation
Capturing groups
(abc)
Captures abc as a group.
Non-capturing groups
(?:abc)
Groups without capturing.
Alternation (OR)
cat|dog
Matches cat or dog.
Backreferences
(["']).*?\1
Matches text wrapped in the same quote character (single or double).
Lookarounds (JavaScript)
Lookbehind support depends on the browser/runtime. Test with the Regex Tester.
Positive lookahead
foo(?=bar)
Matches foo only if followed by bar.
Negative lookahead
foo(?!bar)
Matches foo only if NOT followed by bar.
Positive lookbehind
(?<=foo)bar
Matches bar only if preceded by foo.
Negative lookbehind
(?<!foo)bar
Matches bar only if NOT preceded by foo.
Regex flags (JavaScript)
- g = global (find all matches)
- i = case-insensitive
- m = multiline (^ and $ work per line)
- s = dot matches newline
- u = unicode
- y = sticky
Common regex patterns
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-z]{2,}$
URL
^(https?:\/\/)?([\w-]+\.)+[\w-]+(\/[^\s]*)?$
Phone number
^\+?[0-9][0-9\s().-]{7,}$
IPv4
^(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)$
Date (YYYY-MM-DD)
^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$
Numbers only
^\d+$
Test patterns online
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