Dev Tools
Regex Tester
The Regex Tester lets you write a regular expression, run it against a block of sample text, and instantly see every match highlighted, along with capture groups. It's built for developers validating a pattern before dropping it into code, and for anyone learning regular expressions who wants immediate visual feedback.
The matching engine is your browser's own JavaScript regex implementation, so the pattern and text you enter are evaluated locally and never leave your device or get sent to any server.
How to Use the Regex Tester
- Open the Regex Tester tool.
- Type or paste your regular expression pattern.
- Paste the sample text you want to test it against.
- Review the highlighted matches and capture groups.
Frequently Asked Questions
Which regex flavor does this tool use?
It uses the JavaScript regular expression engine built into your browser, so it supports standard flags like g, i, and m and JavaScript-specific syntax.
Can I test regex patterns against sensitive text like log files?
Yes — matching runs entirely client-side in your browser, so sample text containing sensitive data never gets uploaded anywhere.
Does it show capture groups, not just full matches?
Yes, each match's capture groups are displayed alongside the overall match so you can verify your grouping syntax is working as intended.