Regex cheatsheet

Javascript Regex/Regular Expression cheatsheet This tool processes all data locally in your browser. No information is ever sent to any server. Completely free, no registration required.

How to Use the Regex cheatsheet

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Regex cheatsheet?

A Regex Cheat Sheet (Regex Memo) provides a quick, searchable reference of regular expression syntax, tokens, flags, and examples. Regex is one of the most powerful yet frustrating tools in programming — the syntax is dense and easily forgotten between uses. This reference is organized by what you need to match (digits, words, boundaries, groups, lookarounds, quantifiers) rather than alphabetically, making it a practical coding companion.

How Does It Work?

Browse regex tokens by category: Character Classes, Quantifiers, Anchors, Groups, Lookarounds, Flags, and Common Patterns. Each entry shows the token, what it matches, and a usage example. The search bar finds tokens by name, symbol, or description. Common pattern templates (email, URL, phone, IP address, date) are pre-built for copy-paste use.

Formula

Essential Tokens:\n• . (any char except \\n), \\d (digit), \\w (word), \\s (whitespace)\n• * (0+), + (1+), ? (0 or 1), {n}, {n,m}\n• ^ (start), $ (end), \\b (word boundary)\n• (...) (capture), (?:...) (non-capture), (?<name>...) (named)\n• (?=...) (lookahead), (?<=...) (lookbehind)\n• | (alternation / OR)\n\nCommon Patterns:\n• Email: /\\S+@\\S+\\.\\S+/\n• URL: /https?:\\/\\/[^\\s]+/\n• Phone (US): /\\+?1?\\s*\\(?\\d{3}\\)?[\\s.-]?\\d{3}[\\s.-]?\\d{4}/\n• Date (YYYY-MM-DD): /\\d{4}-\\d{2}-\\d{2}/

Who Uses This Tool?

• Developers looking up regex syntax while coding — quick reference at your fingertips
• Code review: understanding regex patterns in PRs and legacy code
• Interview preparation: brushing up on regex fundamentals
• Writing form validation: templates for email, phone, URL, and custom patterns
• Learning regex systematically from a structured reference

Pro Tips

• Use the 'cheat sheet + tester' workflow: find your pattern in the memo, test it in our Regex Tester, copy the working regex into your code
• For email validation in production, use a simple /.*@.*\\..*/ pattern + a verification email. The RFC-compliant email regex is 6,000+ characters long
• Named capture groups (?<name>...) make regex much more readable and maintainable. Use them instead of numeric group references ($1, $2)
• Remember: regex is greedy by default. Use ? after quantifiers for lazy matching (*?, +?, ??). This is the #1 source of subtle regex bugs

Free online Regex cheatsheet — no signup, 100% client-side processing. All data stays in your browser.