Testing regular expressions
This tool uses your browser’s native JavaScript regex engine, so results match exactly what your code would produce. Adjust flags like g, i, and m to change matching behavior.
Regex Tester
Enter a pattern and test string to see every match, instantly, as you type.
How it works
- 1
Fill in the form fields the tool shows.
- 2
Change modes or toggles if available.
- 3
Copy the generated output when it looks right (often updates live).
Why use this tool
- Runs entirely in your browser — nothing is uploaded to a server.
- 100% free, no sign-up, no limits.
- Works in any modern browser — no app install, no extension, no account.
How to use Regex Tester
Complete the fields in Regex Tester. Output is produced in your browser from those inputs — copy it when ready.
Tips for better results
Empty optional fields if you want a minimal result. Invalid combinations should surface an error message.
Privacy and offline-friendly processing
Whenever possible, Regex Tester processes your data locally with JavaScript in this page. That means drafts, secrets, and unfinished work stay on your device by default. Prefer this workflow when you do not want to upload sensitive text, tokens, passwords, or files to a third-party service.
Frequently asked questions
Which regex flavor is used?
JavaScript’s native RegExp engine, the same one used in browsers and Node.js.
What happens if my pattern is invalid?
A clear error message explains what part of the pattern could not be compiled.
Is my data uploaded when I use this tool?
For most FlyUtils tools, no. Processing happens in your browser with JavaScript. If a tool ever needs a server, that will be stated clearly on the page.
Is Regex Tester free to use?
Yes. Regex Tester is free, with no sign-up and no artificial usage caps for normal personal and work use.
Does Regex Tester work on mobile?
Yes. The page is mobile-first, so you can paste input, tweak options, and copy results from a phone or tablet.