Free Online Regex Tester — Live Highlighting, JS Flags

🔒 All data is processed in your browser. Nothing is uploaded to any server.

Presets

Pattern

Flags

Test String

Matches

—

Quick guide

What can Regex Tester help you do?

Free online regex tester. Live match highlighting, supports g/i/m/s/u flags. Common patterns included.

Best for

Regex Tester helps with quick debugging, API data cleanup, format checks, and small code or config tasks without opening an IDE or installing a package.

How to use it

For Regex Tester, paste the text, code, or configuration into the input area, choose the mode you need, and run it. For large data, test a small sample first.

How to read the result

After using Regex Tester, the output is kept copy-friendly for docs, code, and config files. When validation is available, fix the reported error location before trusting the final output.

Privacy and limits

When using Regex Tester, most processing happens in the browser. Do not paste passwords, private keys, tokens, or unmasked production data into any online tool.

For Regex Tester: Developer tools are for quick inspection and conversion. They do not replace tests, linting, security review, or version control.

Frequently Asked Questions

Is this JavaScript regex?

Yes — ECMAScript engine. May differ slightly from Python/Perl regex.