Regex Tester & Debugger
Test and debug regular expressions with real-time matching, group highlighting, and common pattern library.
- Enter a regular expression pattern and set flags (global, case-insensitive, multiline, etc.).
- Paste sample text to test against — matches highlight live as you refine the pattern.
- Inspect capture groups individually to confirm your extraction logic works.
- Browse the common pattern library for ready-made regexes like email or URL matching.
All processing happens entirely in your browser. Your data never leaves your device.
Key Features
- Real-time pattern matching with live highlighting
- Support for all JavaScript regex flags (g, i, m, s, u, y)
- Capture group inspection — see what each group matched
- Common pattern library with pre-built regex for emails, URLs, IPs, etc.
- Match count and position display
- 100% client-side — your text is never transmitted
About Regex Tester
Regular expressions (regex) are a powerful pattern-matching language used across virtually every programming language and text editor. They allow you to search, match, and extract text based on patterns rather than fixed strings — for example, matching any email address, phone number, or date format in a document.
Writing correct regex patterns is notoriously difficult because the syntax is dense and errors are hard to spot. A regex tester provides instant visual feedback by highlighting matches in real time as you edit the pattern, and by showing capture group contents so you can verify your extraction logic.
ForgeKit's Regex Tester & Debugger supports JavaScript regex syntax with all standard flags (global, case-insensitive, multiline, dotAll, sticky, unicode). It includes a common pattern library with pre-built expressions for emails, URLs, phone numbers, dates, and more.
Frequently Asked Questions
It uses JavaScript's built-in RegExp engine, which supports ECMAScript regex syntax. This is compatible with most regex patterns you'll encounter in web development.
Most basic regex syntax is shared across languages. However, some advanced features (lookbehinds, named groups, atomic groups) vary by language. This tool uses JavaScript regex, which covers the vast majority of common patterns.
Flags modify how the pattern matches: g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — . matches newlines), u (unicode), and y (sticky).