Regex Tester

Write a regular expression, paste your test text, and see every match highlighted instantly — with capture groups and a live match count.

🔒 100% private — nothing is uploaded
g
Flags
0 matches
Matches will appear here, highlighted in context.

How the regex tester works

It uses your browser's built-in JavaScript regular-expression engine, so what you see here is exactly how your pattern will match in practice.

1

Write a pattern

Type your regular expression and flip the flags you need — g for all matches, i to ignore case, and more.

2

Paste your text

Drop in the string you want to search. Every match lights up in context the instant you type.

3

Inspect the groups

See a numbered list of matches with each capture group (and named groups), plus the total match count.

Flags, quick reference

g global finds every match instead of just the first. i ignore case makes letters case-insensitive. m multiline lets ^ and $ match at line breaks. s dotall lets . match newlines too. u unicode enables full Unicode and code-point escapes like \u{1F600}.

Invalid patterns are caught and explained rather than throwing, and runaway patterns are stopped before they can freeze the page — so you can experiment freely.

🔒

Private by design. Your pattern and test text never leave your device — all matching runs entirely in your browser using built-in JavaScript. Nothing is uploaded or stored.

Frequently Asked Questions

What flavour of regular expressions does this use? ▼
It uses your browser's built-in JavaScript regular-expression engine, so what you see here is exactly how your pattern will match in practice.
What do the flags g, i, m, s and u do? ▼
g finds every match instead of just the first, i ignores upper/lower case, m lets ^ and $ match at line breaks, s lets . match newlines, and u turns on full Unicode support.
Can I see my capture groups? ▼
Yes. Below the highlighted text you get a numbered list of matches, each with its capture groups (including named groups) and the position where the match starts.
Do I need to add the slashes and flags to my pattern? ▼
No — type just the pattern itself. The slashes shown around it are only there for display, and you pick the flags with the checkboxes.
What happens with an invalid or very slow pattern? ▼
An invalid pattern is explained in a friendly message instead of breaking, and patterns that could run away (like (a+)+) are caught and paused so the page never freezes.
Is my pattern or test text uploaded anywhere? ▼
No. Everything runs entirely in your browser — your pattern and test text never leave your device and nothing is uploaded or stored.

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