Regex Tester
Test patterns, flags, capture groups, and replacements in real time.
Matches
Hello regex tester
Hello
Index 0 | Groups: Hello
regex
Index 6 | Groups: regex
tester
Index 12 | Groups: tester
Replacement
Hello regex tester
Frequently Asked Questions
Is this regex tester free to use?
Yes, the regex tester is completely free with no login or usage limits.
Does it run offline / is my text sent anywhere?
Yes. Matching uses the browser's native JavaScript RegExp engine, so your pattern and sample text never leave your device.
What regex flags are supported?
Any flags supported by JavaScript's RegExp constructor work, including g (global), i (case-insensitive), m (multiline), and s (dotAll) — just type them into the flags field.
Can I test replacements and capture groups?
Yes. Matches are highlighted in the sample text, each match lists its index and captured groups, and you can enter a replacement pattern (using $1, $2, etc.) to preview the substituted result.