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All regex processing happens in your browser. Your data and patterns never leave your device.
Browser tool● Processed in your browser
Regex Tester
Test, debug, and visualize regular expressions in real time. See matches highlighted in your text, inspect capture groups, and use replace mode to transform strings instantly.
//g
Flags:
01 · Guide
How it works
- 01
Enter your regular expression pattern in the pattern input field
- 02
Select the flags you need (global, case-insensitive, multiline, dotAll)
- 03
Paste or type your test string in the text area below
- 04
View highlighted matches, match details, and captured groups in real time
- 05
Optionally switch to Replace mode to test string replacements
Why use this tool
Real-time Highlighting
See matches highlighted instantly as you type your pattern or modify the test string.
Capture Group Inspection
View each match with its index position and all captured groups for detailed debugging.
Common Patterns Library
Quick-select from pre-built patterns for emails, URLs, phone numbers, IP addresses, dates, and more.
Frequently asked questions
Is my data sent to a server?+
No. All regex matching and replacement happens entirely in your browser using JavaScript. Your patterns and test strings never leave your device.
What regex flavor does this tool use?+
This tool uses JavaScript's built-in RegExp engine, which supports ECMAScript regular expressions including features like lookahead, lookbehind, named capture groups, and Unicode property escapes.
What flags are supported?+
The tool supports four flags: g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line boundaries), and s (dotAll - dot matches newline characters).
Can I test regex replacements?+
Yes. Enable Replace mode, enter your replacement string (supporting $1, $2 backreferences and $& for the full match), and see the transformed result in real time.
What happens if my regex pattern is invalid?+
The tool will display a clear error message describing the syntax issue so you can quickly fix your pattern. It will not crash or produce unexpected results.
04 · More tools
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