Regex Tester
Test regular expressions against text and see all matches highlighted.
About Regex Tester
Regex Tester runs a pattern against sample text and shows every match, capture group and index, so a rule can be verified before it reaches production code.
It supports the common flags — global, case-insensitive, multiline, dotall — and highlights exactly what matched.
How to use Regex Tester
- 1
Enter the pattern
Write the expression without delimiters; choose flags separately.
- 2
Paste the test text
Use realistic input, including the edge cases that break the pattern.
- 3
Inspect matches
Groups are numbered; named groups are listed where supported.
Questions about Regex Tester
Which flavour of regex is used?
JavaScript (ECMAScript) semantics, which differ from PCRE in lookbehind support and some escapes.
Why is my pattern slow?
Nested quantifiers can cause catastrophic backtracking. Anchor the pattern and avoid (.*)+ style constructs.
Does it replace text?
This tool tests matching; a replace preview is a separate feature.
Is my text uploaded?
No, evaluation happens in the browser.
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Last updated November 2026. Files are processed on FilePlume's own hardware and deleted within 60 minutes; nothing is used for training.