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How to Use
- 1Enter your regex pattern in the pattern field.
- 2Set flags: g (global), i (case-insensitive), m (multiline) as needed.
- 3Type or paste your test string in the text area.
- 4See matches highlighted in real time with capture groups listed below.
About Regex Tester
The Regex Tester lets you write and test regular expressions against any test string with instant visual feedback. Every match is highlighted in the text, and capture groups are listed with their index and content for easy verification.
Toggle global (g), case-insensitive (i), and multiline (m) flags to test different matching behaviors. The tool uses JavaScript regex syntax with support for lookahead, lookbehind, named groups, and character classes.
Developers use regex for input validation, search-and-replace, log parsing, data extraction, and web scraping. Test your patterns here before deploying them in code. All testing runs locally — no data is sent to any server.
Frequently Asked Questions
What regex flavor does this tool use?
JavaScript regex syntax, which supports lookahead, lookbehind, named capture groups (?<name>), character classes, quantifiers, and alternation.
What flags are available?
Global (g) finds all matches, case-insensitive (i) ignores letter casing, and multiline (m) makes ^ and $ match line boundaries instead of string boundaries.
How are matches displayed?
Each match is highlighted in the test string with alternating colors. Capture groups are listed below with their group index, name (if named), and matched content.
Can I test patterns meant for Python or PHP?
JavaScript regex is very similar to other languages. Most patterns (character classes, quantifiers, groups, lookahead) work identically across JavaScript, Python, Java, and PHP.
Is my test data sent to a server?
No. All pattern matching runs locally in your browser. Your test strings never leave your device.