Regex Tester
Test, debug, and validate Regular Expressions in real-time with capturing group extraction and flag controls. · Updated
Regex debugging needs immediate feedback on match groups. This tester highlights captures locally without sending sample data to a remote evaluator.
Common errors and fixes
Check for unescaped special characters or unbalanced parentheses/brackets in the pattern.
Why it happens, with a live exampleNothing matches
Confirm flags (especially m and s) and whether you need ^/$ anchors.
Simplify nested quantifiers like (a+)+ on long inputs to avoid locking the tab.
Why it happens, with a live exampleUnicode property escapes failed
Use a modern browser; \p{…} requires Unicode-aware RegExp support.
Options
| Option | Description |
|---|---|
| Multiline mode (m flag) | Enables ^ and $ to match the start and end of each line rather than the entire input string. |
| Dot matches newline (s flag) | Allows the dot (.) token to match newline characters as well. |
FAQ
How do I test a regular expression against sample text?
Enter your regex pattern on the first line, followed by '=== TEST STRING ===' and your sample text.
Does this tool support named capturing groups?
Yes. Patterns using `(?<name>...)` will display their extracted named groups cleanly in the output results.
Which regex engine is used?
It runs using the standard JavaScript V8/ECMAScript RegExp engine directly in your browser.
Where can I find common regex patterns?
Check our free Regular Expressions Cheat Sheet for common patterns like email, URL, IPv4, and UUID validation.