Live highlighting
Matches are highlighted in your test text as you type the pattern.
Regex Tester
Test JavaScript regular expressions with live match highlighting.
- Free
- No sign-up
- Runs in your browser
- Developer
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Why use it
Write a pattern, paste sample text and see every match highlighted as you type, with capture groups listed below. Use it to check validation rules, parse log files or build redirect patterns before they go into code.
Capture groups
Numbered and named groups are listed for every match.
Replace preview
Try a replacement string, including $1 and $<name> references, before using it in code.
How to use it
4 quick steps. Going deeper? Read WordPress plugin development: structure, hooks and security done right.
- 01
Enter the pattern without surrounding slashes.
- 02
Toggle flags: g (all matches), i (ignore case), m (multiline), s (dot matches newline), u (Unicode).
- 03
Paste test text; matches highlight instantly and groups appear in the table.
- 04
Optionally enter a replacement (use $1, $2 or $<name>) to preview the result.
Who it’s for
Typical situations where this tool saves time.
- PHP and JavaScript developersBuild validation patterns for SKUs, phone numbers or IDs and test them on real data.
- Site maintainersPull fatal errors out of long debug logs.
- SEO specialistsCheck redirect patterns before adding them to .htaccess or Nginx.
Questions
Short answers about privacy, limits and how the tool works.
Which regex flavour does this use?
JavaScript (ECMAScript) regular expressions, the same engine used in browsers and Node.js. Most patterns also work in PHP's PCRE, but lookbehind and named-group syntax can differ.
Why does my pattern only find one match?
Without the g flag, JavaScript stops after the first match. Turn on g to find all matches.
Can a pattern freeze the page?
Badly nested quantifiers can backtrack for a long time. The tester caps the number of matches, but avoid patterns like (a+)+ on long text.
Need a tool like this inside your product?
I build custom calculators, admin utilities and integrations for WordPress, Laravel and Next.js teams.