Regex Tester
The Regex Tester lets you build and test regular expressions against sample text in real time, highlighting matches and capture groups as you type.
Test patterns instantly
Enter a regular expression and some sample text and the tester highlights every match live, so you can refine a pattern by trial and error instead of guessing. It shows capture groups, supports flags like global, case-insensitive, and multiline, and can preview a replacement result.
Why regex is worth learning
Regular expressions are the fastest way to validate input (emails, phone numbers), search and replace across large text, and extract structured data. Because the same syntax works across most languages and editors, time spent testing here transfers directly to your code. Testing runs locally in your browser.
Frequently Asked Questions
Does it highlight matches as I type?
Yes. Matches and capture groups update live as you edit either the pattern or the sample text.
Which regex flags are supported?
Common flags such as global, case-insensitive, and multiline are supported, matching standard JavaScript regex behaviour.
Can I test a search-and-replace?
Yes. You can preview the result of replacing matches with a replacement pattern, including group references.
Will these patterns work in other languages?
Core regex syntax is shared across most languages, though some advanced features differ. Basic patterns generally transfer directly.
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