Regex Cheat Sheet
Last updated
Character classes
Match a single character from a set.
| Token | Matches |
|---|---|
. | Any character except a newline |
\d | Any digit (0-9) |
\D | Any non-digit |
\w | Word character (letter, digit, underscore) |
\W | Any non-word character |
\s | Any whitespace (space, tab, newline) |
[abc] | Any one of a, b, or c |
[a-z] | Any lowercase letter in the range |
[^abc] | Any character except a, b, or c |
Quantifiers
Specify how many times the preceding token repeats.
| Token | Matches |
|---|---|
* | Zero or more |
+ | One or more |
? | Zero or one (optional) |
{3} | Exactly 3 times |
{2,4} | Between 2 and 4 times |
{2,} | 2 or more times |
*? | Lazy: as few as possible |
+? | Lazy: one or more, minimal |
Anchors & boundaries
Match positions rather than characters.
| Token | Matches |
|---|---|
^ | Start of the string (or line) |
$ | End of the string (or line) |
\b | A word boundary |
\B | A non-word boundary |
^abc$ | A string that is exactly abc |
\bword\b | word as a whole word |
Groups & capturing
Group tokens and capture what they match.
| Token | Matches |
|---|---|
(abc) | Capturing group, stored as group 1 |
(?:abc) | Non-capturing group |
(?<year>\d{4}) | Named capturing group year |
(ab)+ | Repeat the whole group |
\1 | Backreference to group 1 |
\k<year> | Backreference to a named group |
Alternation
Match one pattern or another.
| Token | Matches |
|---|---|
a|b | Either a or b |
cat|dog | The word cat or dog |
(jpg|png|gif) | Any one of the alternatives, captured |
gr(a|e)y | gray or grey |
^(yes|no)$ | Exactly yes or exactly no |
Lookarounds
Assert what comes before or after without consuming it.
| Token | Matches |
|---|---|
(?=abc) | Lookahead: followed by abc |
(?!abc) | Negative lookahead: not followed by abc |
(?<=abc) | Lookbehind: preceded by abc |
(?<!abc) | Negative lookbehind: not preceded by abc |
\d+(?= dollars) | Digits only when followed by dollars |
(?<=\$)\d+ | Digits only when preceded by $ |
Flags
Modify how the whole pattern is applied.
| Flag | What it does |
|---|---|
g | Global: find all matches, not just the first |
i | Case-insensitive matching |
m | Multiline: ^ and $ match line ends |
s | Dotall: . also matches newlines |
u | Unicode mode |
x | Extended: ignore whitespace in the pattern |
Common patterns
Ready-to-adapt patterns for everyday validation.
| Pattern | Matches |
|---|---|
^\d+$ | A whole number (digits only) |
^[\w.+-]+@[\w-]+\.[\w.-]+$ | A basic email address |
https?:\/\/[^\s]+ | An http or https URL |
^\d{4}-\d{2}-\d{2}$ | A date like 2026-05-27 |
^\d{3}-\d{3}-\d{4}$ | A US phone number |
^#?[0-9a-fA-F]{6}$ | A 6-digit hex color |
\s+ | One or more whitespace characters |
Every regex token you reach for, on one page. This regex cheat sheet is a quick reference for building regular expressions - character classes, quantifiers, anchors, groups, alternation, lookarounds, and flags.
The syntax here follows the common PCRE / JavaScript flavor used by most languages. Copy a pattern, or try it live in the regex tester tool to see exactly what it matches, with the JS playground a click away.
Regex cheat sheet FAQ
Is this regex cheat sheet free?
Yes. This regex cheat sheet is completely free, with no sign-up required. Bookmark it and come back whenever you need to look up a token, quantifier, or flag.
What is the difference between greedy and lazy quantifiers?
Greedy quantifiers like
* and + match as much as possible, then give characters back if the rest of the pattern needs them. Lazy quantifiers, written by adding ? (such as *? or +?), match as little as possible and only expand when forced. For example, on <a><b> the pattern <.+> greedily matches the whole string, while <.+?> matches just <a>.What is a capture group in regex?
A capture group is a part of a pattern wrapped in parentheses, like
(\d{4}), whose matched text is saved and numbered so you can reuse or extract it. You reference it later with a backreference such as \1, or name it with (?<year>\d{4}) for clarity. If you want to group tokens without capturing, use a non-capturing group (?:...).Can I practice regex online?
Yes. Open the regex tester tool to type a pattern and see exactly what it matches against your own text, live in the browser. You can also drop any pattern into the JS playground to use it in code. When you want structure, Coddy's free interactive course covers the building blocks step by step.
Is this cheat sheet good for beginners?
Yes. It is organized from character classes and quantifiers (the foundations) down to lookarounds and ready-made patterns, so you can start matching simple text right away and grow into advanced expressions.
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