Regex Tester
Test regex matches against input text.
About the Regex Tester
This Regex Tester lets you try a regular expression against sample text and see what matches before you drop the pattern into code, analytics filters, or a CMS rule. Regex is powerful and easy to get wrong; testing live saves broken forms and silent validation bugs.
Enter a pattern, optional flags, and input text. Matches are shown so you can tighten or loosen the expression until it behaves the way you expect.
Common uses
- Validating emails, slugs, order IDs, or phone-like strings in forms
- Extracting product codes or tracking numbers from messy paste text
- Building find/replace patterns for cleanups in logs or exports
- Teaching or documenting a pattern before sharing it with a teammate
How to use
- Paste representative sample text into the input area (include edge cases).
- Type your regular expression and choose flags if needed (for example case-insensitive).
- Run the test and inspect which parts matched — and which did not.
- Adjust the pattern until false positives and false negatives disappear.
Tips that prevent pain
- Start strict, then relax. Overly broad
.*patterns often match too much. - Escape special characters when you mean them literally (
.,(,),?). - Test empty input, leading/trailing spaces, and unicode if your users paste from Word.
FAQ
Which regex dialect is this? Browser JavaScript regex. Patterns may differ slightly from PCRE/Python — re-test in your runtime before shipping.
Can regex parse HTML? Prefer a real HTML parser for documents. Regex is fine for small, controlled snippets only.