Regex tester for the JS flavor you actually ship

regex101 wins for multi-flavor deep dives. This page is the opposite bet: paste pattern + flags + sample, see matches immediately in an App Shell — no account, no latency to a remote runner.

chars: 116

Input

When to use

Quick /pattern/gi checks while coding, or previewing a replace before you commit.

Examples

Input

pattern: \d+
flags: g
text: a1b22

Output

matches: 1, 22

How it works

new RegExp(source, flags) → matchAll / replace preview. Invalid patterns show errors. Engine is JavaScript regex — not PCRE/Python.

Common pitfalls

JS lacks some PCRE features; lookbehinds vary by browser age.
Catastrophic backtracking can freeze the tab.
Dotall / multiline flags change what `.` and `^$` mean.

How this differs

Live JS regex. Slugify/case tools transform text without patterns. Diff compares two blobs.

FAQ

PCRE/Python flavors?

Not here — JS only; use regex101 for others.

Catastrophic backtracking?

Very large inputs may freeze the tab; keep samples sane.

Uploaded?

No.

Replace mode?

Yes if UI includes replacement string.

Runs in your browser. Nothing is uploaded. Not a security product —hashes and JWT decode are for debugging, not password storage or auth advice.