Regex Builder

A regular expression (regex) is a sequence of characters that forms a search pattern for matching text. It works by defining a pattern that the regex engine uses to search through text and find matches. Regex is used in programming, data validation, text processing, and search operations. Our regex builder helps you create and test these patterns in real-time with instant feedback.

Flags modify how the regex pattern is applied: 'g' (global) finds all matches, 'i' (insensitive) ignores case, 'm' (multiline) matches across lines, 's' (dotAll) allows '.' to match newlines, 'u' (unicode) handles Unicode characters, and 'y' (sticky) matches from the last position. Our tool lets you toggle these flags to control matching behavior.

Common patterns include: email validation (`\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b`), phone numbers (`\b\d{3}[-.]?\d{3}[-.]?\d{4}\b`), URLs (`\bhttps?://[^\s]+`), ZIP codes (`\b\d{5}(?:-\d{4})?\b`), and IP addresses (`\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b`). Our quick patterns library includes these and many more.

Email validation uses the pattern: `\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b`. This matches standard email formats like `name@domain.com`, `name.surname@company.co.uk`, and `user+tag@example.org`. The pattern ensures the email has a local part, '@' symbol, domain, and a valid TLD of at least 2 characters. Use the 'i' flag for case-insensitive matching.

Yes, our regex builder is fully responsive and works on all devices—desktops, laptops, tablets, and smartphones. You can build and test regular expressions directly from your mobile browser with full functionality including real-time matching, pattern library, and copy features.

Yes, your privacy is our top priority. All regex processing happens locally in your browser—your patterns and test data are never uploaded to any server. We don't store, share, or access your regex patterns or test strings. This makes our tool completely safe for testing with sensitive data and proprietary patterns.

Most major programming languages support regex including: JavaScript, Python, Java, PHP, C#, Ruby, Perl, and more. While the core syntax is similar across languages, there are small differences in features like lookbehind assertions, named groups, and Unicode support. Our tool uses JavaScript regex syntax, making it compatible with web development, Node.js, and frontend applications.

Yes, you can easily copy your regex pattern using the "Copy Pattern" button. The tool also saves your last used pattern in your browser's local storage, so you can continue working even after refreshing the page. For permanent storage, we recommend saving your patterns in your project's documentation or version control.