Regex Generator

Regex Generator - Build & Test Regular Expressions Online

Build and test regular expressions with our interactive Regex Generator. Start from common presets like email, URL, phone number, IP address, and more, or write your own pattern.

Select a preset pattern from the dropdown (email, URL, phone, IP address, credit card, etc.) or choose "Custom" to write your own regular expression. The regex pattern appears in the editor where you can modify it. Enter sample text in the test area below, and the tool highlights all matches in real-time as you type. Adjust regex flags (case insensitive, multiline, global) using the checkboxes. The match results section shows all captured groups and their positions. Copy the final regex pattern for use in JavaScript, Python, or other languages. All matching happens in your browser using JavaScript's RegExp engine.

Developers validate user input in forms by testing regex patterns against sample data before implementing validation. Data scientists extract structured information from unstructured text using carefully crafted patterns. Security engineers create WAF rules to detect attack patterns in HTTP requests. Log analysts parse and extract specific fields from application or server logs. Text processing scripts use regex to find-and-replace patterns across large codebases. Content moderators build regex filters to detect prohibited content patterns in user submissions.

Start with a preset and modify it rather than building complex patterns from scratch. Test your regex against both valid and invalid inputs to catch false positives and false negatives. Remember that regex dialects vary between languages—JavaScript regex may behave differently than Python or PCRE. Use capturing groups ( ) to extract parts of matches, and non-capturing groups (?: ) when you don't need to extract. Escape special characters like . * + ? [ ] { } ( ) ^ $ | \ with backslashes. For email validation, perfect regex is impossible—use a basic pattern and send a confirmation email.

All processing happens directly in your browser. Your files never leave your device — no server uploads, no cloud storage, no data retention. The tool works offline once loaded, requires no registration, and is completely free with no usage limits.