Regex Tester

Test, evaluate, and highlight regular expressions in real-time.

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Commonly Used Regex

What is a Regex Tester?

Regular expressions (Regex) are incredibly powerful search patterns, but they are notoriously difficult to write and debug. A regex tester provides a safe, real-time environment to evaluate your patterns against test strings. It instantly highlights exactly what your pattern is matching, ensuring your logic is flawless before deploying it in code.

How to use

  • 1Type your regular expression pattern in the main input field.
  • 2Add or remove regex flags (like 'g' for global or 'i' for case-insensitive) in the trailing input.
  • 3Enter or paste the text you want to search through into the 'Test String' box.
  • 4Matches will instantly illuminate in the 'Match Results' viewer below.

Regex Tester guide

Use this regex tester to develop, debug, and explain regular expressions against realistic sample text. Live highlighting makes it easier to see exactly what a pattern matches before adding it to application code.

When to use it

  • Validate an email, slug, identifier, or log-line pattern.
  • Check global, case-insensitive, and multiline flag behavior.
  • Find accidental matches before using a regex in production code.

Match version numbers

Input

Pattern: \bv?\d+\.\d+\.\d+\b
Text: Released v2.4.1 and 3.0.0 today.

Result

Matches: v2.4.1, 3.0.0

Common questions

Which regex syntax does the tester use?
It uses the JavaScript RegExp engine available in modern browsers.
Why is my pattern not matching?
Check escaping, flags, word boundaries, and whether the sample text contains hidden whitespace or line breaks.

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