Free Regex Tester
This regex tester runs JavaScript patterns against sample text live, highlighting matches and counting them, with common flags to toggle. It is designed for validating emails, extracting data and debugging patterns before they ship. Nothing is uploaded.
How it works
The pattern compiles with selected flags and executes against the text; matches wrap in highlight marks with an index list beneath. Invalid patterns report the engine error instead of failing silently. Note the tester uses the JavaScript flavour: other languages differ on lookbehind andUnicode handling.
Example
| Pattern | Finds |
|---|---|
\d+ | Digit runs like 2026 |
Frequently asked questions
Why did my pattern fail?
Usually an unescaped special character or wrong flavour assumption. Read the reported error position first.
What do the flags do?
g finds every match instead of the first; i ignores case; m makes ^ and $ work per line.
Is this the same as Python or PHP regex?
Mostly, but flavours differ on details like lookbehind. Always re-test in the target language.
How do I match an email?
The default sample pattern covers common addresses, but no short pattern matches every valid email. Validate deliverability separately.
Is my text uploaded?
No. Testing happens locally in your browser.
Related tools
- Text Cleaner , prepare test data.
- JSON Formatter , validate structured text.
- Link Extractor , pull matches a simpler way.
- Guide: Small Business Digital Toolkit