Regex Tester
Test and debug regular expressions with real-time matching, capture groups, and replace preview.
Match Details
| # | Match | Index | Groups |
|---|---|---|---|
| 1 | support@example.com | 14 | - |
| 2 | sales@company.co.uk | 37 | - |
| 3 | hello@test.org | 70 | - |
Common Patterns
Pattern Explanation
- . - Any character (except newline)
- + - One or more occurrences
Quick Reference
. Any char\d Digit\w Word\s Space* 0+ times+ 1+ times? Optional^$ Start/End## What does Regex Tester do? Test and debug regular expressions with real-time matching, capture groups, and replace preview. This free online tool runs entirely in your browser, ensuring your data stays private.
How to use Regex Tester
- 1
Enter Pattern
Type your regular expression pattern in the pattern field.
- 2
Set Flags
Toggle flags: g (global), i (ignore case), m (multiline), s (dotall), u (unicode).
- 3
Test String
Paste or type the text you want to test against the pattern.
- 4
Review Matches
See highlighted matches, capture groups, and match details in real-time.
Related Tools
Frequently Asked Questions
What are regex flags?
Flags modify regex behavior: g (find all matches), i (ignore case), m (^ and $ match lines), s (dot matches newlines), u (unicode support).
How do capture groups work?
Use parentheses () to create capture groups. Access them in replacements with $1, $2, etc. The full match is $&.
Why is my regex not matching?
Check for proper escaping (use \ for special chars), ensure flags are correct, and verify your pattern syntax.
What is the difference between * and +?
* matches zero or more occurrences, + matches one or more. Use * when something is optional, + when required.
How do I match special characters literally?
Escape them with backslash: \. matches a literal dot, \+ matches a plus sign, etc.