Regex Tester
Test regular expressions live against sample text, with match groups and replace mode.
How to Use Regex Tester
Enter your regular expression pattern into the pattern field, then select which flags you want to apply — g for global matching, i for case-insensitive matching, m for multiline mode, s for dot-matches-newline, and u for full Unicode support. Paste or type your sample text into the test string textarea below. As soon as both the pattern and test string are populated, the tool evaluates the regex live and shows you a clear 'Match' or 'No Match' indicator at the top, so you know immediately whether your pattern works at all. If there are matches, a detailed list shows each one along with its exact position in the string and any capture groups it produced, making it easy to verify that your groups are extracting the right pieces of data. This is especially useful when building patterns for form validation, data extraction, or search-and-replace logic, since you can see precisely what a real engine matches rather than just guessing based on the pattern syntax. The tool also includes a replace test mode, where you can enter a replacement string — including group references — and preview exactly what the resulting text would look like after a `replace()` call, without needing to run any code yourself. Because it uses the browser's native `RegExp` engine, the behavior matches exactly what you'd get in real JavaScript code.
Why Use Our Regex Tester?
Regular expressions are powerful but notoriously easy to get subtly wrong, and debugging a broken pattern by repeatedly editing and re-running code is slow. Our Regex Tester gives you instant, live feedback as you type, showing exactly what matches, where, and with what capture groups, so you can iterate on a pattern in seconds instead of minutes. Because it runs on the browser's native `RegExp` engine, there's zero risk of behavioral differences between what you test here and what actually runs in your JavaScript application — a common frustration with tools that use a different regex flavor under the hood. The built-in replace preview means you can validate a find-and-replace operation safely before running it against real data, avoiding accidental data corruption from a slightly wrong pattern. It's free, requires no installation, and is fast enough to use as a scratch pad while actively writing code, letting you copy a verified working pattern straight into your project with confidence.
Frequently Asked Questions
Is the Regex Tester free to use?
Yes. The Regex Tester is completely free with no usage limits, no signup, and no hidden fees.
Do I need to create an account?
No account or signup is required. Just open the tool and start using it immediately.
Is my data safe when using this tool?
Yes. All processing happens directly in your browser, so your data is never uploaded to a server or stored anywhere.
Does the Regex Tester work on mobile devices?
Yes, the tool is fully responsive and works on any modern browser, including mobile phones and tablets.
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