Regex Cheat Sheet
Quick reference for regular expression syntax. Character classes, quantifiers, anchors, groups, lookaheads, and common patterns — all in one page.
Character Classes
Anchors
Quantifiers
Groups & References
Lookahead & Lookbehind
Flags
Common Patterns
Character Classes
| . | Any character except newline |
| \d | Digit (0-9) |
| \D | Not a digit |
| \w | Word character (a-z, A-Z, 0-9, _) |
| \W | Not a word character |
| \s | Whitespace (space, tab, newline) |
| \S | Not whitespace |
| [abc] | Any of a, b, or c |
| [^abc] | Not a, b, or c |
| [a-z] | Any character from a to z |
Anchors
| ^ | Start of string (or line with m flag) |
| $ | End of string (or line with m flag) |
| \b | Word boundary |
| \B | Not a word boundary |
Quantifiers
| * | 0 or more |
| + | 1 or more |
| ? | 0 or 1 (optional) |
| {3} | Exactly 3 |
| {3,} | 3 or more |
| {3,5} | Between 3 and 5 |
| *? | 0 or more (lazy) |
| +? | 1 or more (lazy) |
Groups & References
| (abc) | Capture group |
| (?:abc) | Non-capturing group |
| (? |
Named capture group |
| \1 | Backreference to group 1 |
| a|b | Alternation (a or b) |
Lookahead & Lookbehind
| (?=abc) | Positive lookahead |
| (?!abc) | Negative lookahead |
| (?<=abc) | Positive lookbehind |
| (? | Negative lookbehind |
Flags
| g | Global — find all matches |
| i | Case-insensitive |
| m | Multiline — ^ and $ match line start/end |
| s | Dotall — . matches newline |
| u | Unicode support |
Common Patterns
| ^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,}$ | Email (basic) |
| ^https?:\/\/[\w.-]+\.[a-zA-Z]{2,} | URL |
| ^\d{1,3}(\.\d{1,3}){3}$ | IPv4 address |
| ^#?([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$ | Hex color |
| ^\d{4}-\d{2}-\d{2}$ | Date (YYYY-MM-DD) |
| ^\+?\d{10,15}$ | Phone number (international) |
Try It Live
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Step-by-Step Guide
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