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Regex Tester

Utilities Free Updated 4 Oct 2026
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ⓘ About this tool 🔄 Last updated 4 Oct 2026 ✓ Reviewed by TopToolAI Team

Tests a JavaScript regular expression against a test string, highlighting every match and listing them separately. Runs entirely in your browser.

How to use Regex Tester

Step-by-step guide to the boxes below. Open it only if you need help.

  1. 1
    Regex pattern (no slashes) Text

    The pattern without slashes, e.g. \d+ matches numbers.

    Example: \d+

  2. 2
    Flags (e.g. gi) Text

    Options: g finds all matches, i ignores capital letters, m treats each line separately.

    Example: g

  3. 3
    Test string Text box

    The text you want to test the pattern against.

  4. 4
    Press “Test”

    Click the button under the boxes. If something is missing or not valid, a short message tells you which box to fix.

  5. 5
    Read your result

    Your answer appears under the button, with a short note in plain words where it helps. Change any box and press again to compare different numbers.

Embed this calculator on your website

Want this calculator on your own site? Copy the code below and paste it into the HTML of any page or post. It works the same as it does here. If you do not mind, leave the small link under it in place.

Regex Tester FAQs

Which regex flavor does this use?
JavaScript's native regex engine (the same one browsers use), which is very close to most common flavors but not identical to PCRE or Python's re module.
What do the flags g, i and m do?
g finds all matches, i ignores letter case and m makes ^ and $ match at the start and end of each line.
How do I match an email address with regex?
A simple pattern is [\w.+-]+@[\w-]+\.[\w.]+. Real-world email validation is more complex.
What does the dot (.) mean in regex?
It matches any single character except a newline.

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