Why test regex online instead of in my code?

Online testers let you iterate on patterns instantly without modifying and re-running code. They also display captures and match positions visually, which speeds up debugging significantly.

Does it support regex lookaheads?

Yes. JavaScript regex supports lookaheads ((?=...) and (?!...)) and lookbehinds ((?<=...) and (?<!...)), both of which work in the FixTools tester.

Can I test regex across multiple lines?

Yes. Enable the m (multiline) flag so that ^ and $ match the start and end of each line rather than the full string.

What happens if my regex has an error?

If your pattern is invalid, the tool shows an error message describing the syntax problem so you can correct it.

Can I save my regex patterns?

You can bookmark the page URL, which updates to reflect your current pattern in supported browsers, or copy the pattern for use in your code.

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Test Regex Online — Live Match Highlighting

Q: Can I test regex across multiple lines?

Yes. Enable the m (multiline) flag so that ^ and $ match the start and end of each line rather than the full string.

Q: What happens if my regex has an error?

If your pattern is invalid, the tool shows an error message describing the syntax problem so you can correct it.

Q: Can I save my regex patterns?

You can bookmark the page URL, which updates to reflect your current pattern in supported browsers, or copy the pattern for use in your code.

Skip the write-run-debug cycle. FixTools lets you test regex patterns live: type your pattern and see matches highlighted immediately as you edit. Adjust flags, tweak the pattern, and iterate until it behaves exactly as expected.

⚡ Use Tool Now How it works

Cost: Free forever
Sign-up: Not required
Processing: In your browser
Privacy: Files stay local

⚡

Instant live match highlighting

🔒

Supports all standard regex flags

✨

Capture group results shown inline

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Regex Tester

All processing happens in your browser — your files are never uploaded to any server.

🚀Open Regex Tester

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How to use this tool

💡

Type your regex pattern and paste your test string. Matches are highlighted in real time, and the match list updates as you edit the pattern.

How It Works

Step-by-step guide to test regex online — live match highlighting:

1
Open the Regex Tester
Navigate to the FixTools Regex Tester.
2
Enter your pattern
Type your regex pattern in the pattern input field.
3
Set flags
Choose any needed flags from the flag selector.
4
Add a test string
Paste the text you want to match against.
5
See live results
Matches are highlighted instantly. Edit your pattern and watch the results update in real time.