Regex Tester
Test and debug regular expressions in real-time. See matches highlighted with capture groups. No data sent to server.
Flags:
Regular Expression
Presets
Test String
Matches
0 matches found
Hello world! test@example.com 123-456-7890
Match Details
Enter a pattern to see matches
About Regex Tester
Regular expressions (regex) are patterns used to match and extract text. This tool helps you build and debug regex by showing matches highlighted in your test string, plus capture groups and match indices.
Common patterns
- \\d — digit; \\w — word character; \\s — whitespace
- + — one or more; * — zero or more; ? — zero or one
- [a-z] — character class; ^ — start; $ — end
- (...) — capture group; (?:...) — non-capturing group
Frequently Asked Questions
What is a regex tester?
A regex tester lets you write a regular expression pattern and test it against sample text. You see matches highlighted in real-time, plus capture groups and match positions. It helps debug and validate regex before using it in code.
Is my data sent to a server?
No. All regex testing runs in your browser. Your pattern and test text never leave your device.
What do the flags g, i, and m mean?
g = global (find all matches, not just the first). i = case insensitive. m = multiline (^ and $ match line start/end).
How do capture groups work?
Wrap parts of your pattern in parentheses (e.g. (\d+)) to create capture groups. Each group's matched text is shown in the Match Details section.
Is this regex tester free?
Yes, completely free with no sign-up or limits.