A searchable cheat sheet for regular expressions — character classes, anchors, quantifiers, groups, alternation, lookaround, and flags — each with a plain-English meaning. It is handy when you are mid-pattern and just need to recall what \b, *?, or (?<=...) does without leaving your work.
How it works
The reference groups every common regex token by category — character classes, anchors, quantifiers, groups, lookaround, and flags — and shows a concise description of what each matches. Type a token or keyword such as digit, lookahead, or quantifier into the search box and the list filters instantly to the matching entries. It is purely a static lookup that follows the conventions shared by JavaScript and PCRE, so nothing is executed against your data.
Example
Searching for digit surfaces the character-class tokens. A few of the most-used tokens:
| Token | Matches |
|---|---|
. | Any character except newline |
\d / \D | A digit / a non-digit |
\w / \W | A word character / non-word character |
\s / \S | Whitespace / non-whitespace |
^ / $ | Start / end of string (or line with m) |
\b | Word boundary |
* + ? | 0+, 1+, 0 or 1 (add ? for lazy) |
{n,m} | Between n and m repetitions |
(?=...) / (?!...) | Positive / negative lookahead |
(?<=...) / (?<!...) | Positive / negative lookbehind |
Everything runs in your browser; nothing is uploaded.