Regex Tester
Test regular expressions with real-time matching and group capture.
About Regex Tester
Regular expressions (regex) are powerful patterns for matching, searching, and manipulating text — but writing them correctly can be tricky. This Regex Tester gives you real-time feedback as you type: matches are highlighted in the test string, captured groups are displayed, and any syntax errors in your pattern are shown immediately.
The tool supports all JavaScript regex flags including global (g), case-insensitive (i), multiline (m), and dotAll (s). You can see every match, their indices, and the contents of each capture group and named group.
Whether you're validating user input, parsing log files, or performing text transformations, testing your regex in an interactive environment before deploying it saves hours of debugging.
Features
- ✓Real-time match highlighting as you type
- ✓Capture group and named group display
- ✓Support for all regex flags (g, i, m, s, u)
- ✓Match count and index information
- ✓Syntax error detection for invalid patterns
- ✓Runs entirely in the browser
Common Use Cases
- →Validating email addresses, phone numbers, or zip codes
- →Parsing log files or structured text data
- →Building search-and-replace patterns for code editors
- →Extracting data from URLs or strings
- →Learning and experimenting with regex syntax
Frequently Asked Questions
Which regex flavor does this tool use?
This tester uses JavaScript's built-in RegExp engine, which is compatible with most modern regex syntax.
Can I test multiline strings?
Yes. Use the multiline (m) flag to make ^ and $ match start and end of each line. Enable dotAll (s) to make . match newlines.
How do I match a literal dot or bracket?
Escape special characters with a backslash. For example, use \. to match a literal dot instead of any character.