Regular Expressions Cheat Sheet
Quick reference for regular expression syntax including characters, quantifiers, anchors, groups, and common patterns.
Last updated: 2026-08-27
| syntax | category | description |
|---|---|---|
| . | Characters | Any character except newline |
| \d | Characters | Any digit (0-9) |
| \D | Characters | Any non-digit |
| \w | Characters | Any word character (a-z, A-Z, 0-9, _) |
| \W | Characters | Any non-word character |
| \s | Characters | Any whitespace (space, tab, newline) |
| \S | Characters | Any non-whitespace |
| \b | Characters | Word boundary |
| \B | Characters | Non-word boundary |
| [abc] | Characters | Any of a, b, or c |
| [^abc] | Characters | None of a, b, or c |
| [a-z] | Characters | Any lowercase letter |
| [a-zA-Z] | Characters | Any letter |
| * | Quantifiers | 0 or more occurrences |
| + | Quantifiers | 1 or more occurrences |
| ? | Quantifiers | 0 or 1 occurrence (optional) |
| {n} | Quantifiers | Exactly n occurrences |
| {n,} | Quantifiers | At least n occurrences |
| {n,m} | Quantifiers | Between n and m occurrences |
| ^ | Anchors | Start of string |
| $ | Anchors | End of string |
| \A | Anchors | Start of string (absolute) |
| \Z | Anchors | End of string (absolute) |
| (...) | Groups | Capture group |
| (?:...) | Groups | Non-capturing group |
| (?=...) | Groups | Positive lookahead |
| (?!...) | Groups | Negative lookahead |
| (?<=...) | Groups | Positive lookbehind |
| (?<!...) | Groups | Negative lookbehind |
| (?P<name>...) | Groups | Named capture group |
| | | Alternation | OR — match either side |
| \ | Escaping | Escape special character |
| ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ | Common Patterns | Email address |
| ^(https?:\/\/)?[\w.-]+\.[a-zA-Z]{2,}.*$ | Common Patterns | URL |
| ^\d{4}-\d{2}-\d{2}$ | Common Patterns | Date (YYYY-MM-DD) |
| ^\d{3}-\d{3}-\d{4}$ | Common Patterns | US phone number |
| ^\d{16}$ | Common Patterns | Credit card number (16 digits) |
| ^[A-Z]{2}\d{2}[A-Z0-9]{1,30}$ | Common Patterns | IBAN (simplified) |
| ^#?([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$ | Common Patterns | Hex color |
| ^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$ | Common Patterns | IPv4 address |
| ^[a-z0-9-]+$ | Common Patterns | Slug (kebab-case) |
| i | Flags | Case-insensitive matching |
| g | Flags | Global matching (find all) |
| m | Flags | Multiline mode (^ and $ match line boundaries) |
| s | Flags | Dot matches newline |
| u | Flags | Unicode mode |
| y | Flags | Sticky matching |