About Regex Tester
The Regex Tester helps developers test regular expressions in real time. It supports JavaScript regex syntax with match highlighting, group display, and replacement functionality. Regular expressions are essential for form validation, text extraction, and log analysis. This tool eliminates the inefficient write-regex-then-run-code loop.
How to Use
- Enter your regex pattern in the pattern input
- Paste the text to test in the test area
- All matches are highlighted in real time in the results panel
- Use flags (g global, i case-insensitive, m multiline) to adjust behavior
- Switch to the Replace tab to test regex replacements
Frequently Asked Questions
- Which regex syntax is supported?
- This tool uses the native JavaScript RegExp engine, supporting all JS regex features including capture groups, lookahead/lookbehind assertions, and Unicode properties.
- Do special regex characters need escaping?
- Yes. Regex meta-characters like . * + ? ^ $ { } [ ] ( ) | \ must be escaped with a backslash to match them literally.
- Why does the same regex behave differently in another language?
- Regex engines differ in features, default flags and Unicode support. This tool uses JavaScript RegExp, so test again in the target runtime before relying on cross-language behavior.