How do I test a regex online?

Enter your pattern and flags, paste test text, and the tool highlights matches and capture groups live — in your browser.

Which regex flags are supported?

Common JavaScript flags — g (global), i (case-insensitive), m (multiline), and s (dotAll) — are supported.

Is the online regex tester private?

Yes. Matching is 100% client-side; your text and patterns are never uploaded.

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Regex Tester

Regex Tester — free online developer tool, 100% client-side. No upload, no signup, no tracking. Private by design.

Regular Expression

Flags

Test text

Enter a pattern above.

Matches (highlighted)

Test Regular Expressions Online — Free, Private, Live Matches

Write and test regular expressions against your own text with live match highlighting and capture-group breakdowns. This free online regex tester is built for developers who want instant feedback without leaving the browser.

Why this tool is useful

Validate patterns before dropping them into code.
See exactly what your regex matches, group by group.
Learn regex faster with immediate visual feedback.

How it works (client-side)

Enter your regex and choose flags (global, case-insensitive, etc.).
Paste the test text below.
Matches and capture groups highlight instantly as you type.

Frequently asked questions

Which regex flavor is supported?

JavaScript's native RegExp flavor, which covers the vast majority of everyday patterns.

Can I use flags?

Yes — global (g), case-insensitive (i), multiline (m), and more can be toggled.

Is my text uploaded?

No. Matching runs entirely in your browser.