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Regex tester.
Live JavaScript regex matching with flags, capture-group tables and a cheatsheet. Input-capped for safety.
| $1 | aisha |
| $2 | example.com |
| ?‹user› | aisha |
| ?‹host› | example.com |
Cheatsheet
. — any char
\d — digit
\w — word char
\s — whitespace
* — 0+
+ — 1+
? — 0/1
{2,4} — repeat
^…$ — anchors
(…) — group
(?:…) — non-group
a|b — either
[a-z] — range
[^…] — negate
\b — boundary
(?<n>…) — named
🔒 Privacy — runs 100% locally
No uploads · no cookies · works offline after load. View Source if you don't believe it.
How to use.
- Type a pattern — matches highlight live with a count.
- Toggle flags g/i/m/s/u/y and inspect the group table.
- Use the cheatsheet for syntax you forget monthly.
Related tools.
Formatters
JSON formatter
Pretty-print, minify and validate JSON with exact error pointers. Pasted text never leaves this tab.
Converters
Timestamp converter
Unix seconds or milliseconds to ISO, UTC and relative time — with automatic unit detection and bulk rows.
Converters
JSX to HTML
HTML to JSX is near-lossless; JSX to HTML covers presentational components. Includes a live render check.
FAQ.
Which flavor?
JavaScript (RegExp) — lookbehind and named groups supported per your browser. PCRE-only features like recursion won't work.
Can a bad pattern hang my tab?
Inputs are capped at 20k chars and 200 matches shown. Pathological patterns can still spin — keep quantifiers nested carefully.