VOLTUTILS

Regex Tester

Test regular expressions against target strings.

100% Local Processing

About the Regex Tester

Regular expressions are powerful but hard to write blind. This tool lets you live-test your regex patterns against a text string using standard JavaScript Regex syntax. Easily experiment with different flags (g, i, m) without executing arbitrary code.

How to test a regular expression

  1. Enter a JavaScript regular-expression pattern, without surrounding slashes unless the tool expects them.
  2. Add flags such as g for all matches, i for case-insensitive matching, or m for multiline input.
  3. Paste the target text and inspect the matches, groups, and error message shown by the tester.

Examples and worked results

Simple email-shaped match

Input
Pattern: [^@\s]+@[^@\s]+\.[^@\s]+
Text: contact@example.com
Result
contact@example.com

This simple pattern is for experimentation and is not a complete email-validation policy.

The JavaScript RegExp engine

The tester creates a native JavaScript RegExp in the browser and applies it to the target text. Flags change matching behaviour: g returns multiple matches, i ignores letter case, and m changes the meaning of line anchors.

Common use cases

  • Checking a pattern before adding it to JavaScript code
  • Learning how groups, anchors, and flags affect matches
  • Testing log, identifier, or input patterns against sample text

Important notes and limitations

  • Patterns can be valid JavaScript but still be wrong for the business rule you are trying to express.
  • Very broad or nested patterns can be expensive on large input; test carefully before using them on untrusted data.

Practical tips

  • Start with a small target string and add one requirement at a time so a failed match is easier to explain.

Frequently Asked Questions

What regex engine does it use?

It uses the native JavaScript RegExp engine executed safely in your browser.

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